LUGNET News : ~3813/

14-speed gearbox ver3 pic8 (shifter)

LDraw files:

lego 14-speed 3 remake.ldr

Brickshelf Gallery:

14speed3Remake

YouTube videos:

This design is remake which has more compact design and better placed shift levers. Original design is still available on page Junkyard if you want to check it.

Scania’s GRS895 12-speed transmission is actually 14-speed transmission without crawler gears, there are no changes in ratios or gear steps. So here is how to get 12-speed lego conversion of this 14-speed transmission, it’s just removing crawler gear’s 16 teeth clutch gear. New overall gear ratio is only 12,50 so 12-speed version suits to linehaul trucks.

Picture links:

14-speed ver4 pic6 (no bricks)

12-speed conversion

A.4. Version IV, 6 reverse gears, overall gear ratio 40,00:

Splitter + range + main gearbox, also 12- & 13-speed conversions
Inspirer: Volvo I-Shift with crawler gears

I-Shift is Volvo’s 12-speed automated transmission. As four options you can have one or two crawler gears with or without reverse crawler (for more info check link above). Here is described maximum choice 14-speed with 6 reverse gears. In I-Shift crawler gear is not in main gearbox but extra gear pair in front mounted splitter. In normal use I-Shift with crawler gears is same as basic 12-speed (2x3x2) but when needed crawler gear is chosen with main gearbox’s gears 1st, 2nd and reverse giving gears C1, C2 and RC. So crawler position overrides normal splitter. In normal crawler gear transmission crawler gear step CL-CH is as small as splitter step but in this Volvo’s design crawler gears have large steps: gear step C1-C2 is as large as main gearbox’s step 1-2, and also step C2-1L can be chosen larger than splitter step. While basic 12-speed I-Shift has overall gear ratio suitable for heavy hauling adding two large step crawler gears give this transmission very large overall gear ratio, so it’s severe duty transmission. Crawler position can be chosen also with high range reverse so you have 6 reverse gears altogether: RC, RL and RH in both ranges. All in all this transmission is a little bit complex to operate but driver doesn’t need to pay attention while transmission is automated.

Picture links:

14-speed ver4 pic7 (no bricks)

LDraw files:

lego 14-speed 4 rm.ldr

Brickshelf Gallery:

14speed4Remake

YouTube videos:

Building example 14-, 13- & 12-speed

Lego version is remake with more compact design and easier range shifts but scaled ratio set is unchanged. Original design is still available on page Junkyard if you want to check it. Lego version has very good geometrical gear steps: they vary only from range shift’s 1,27 and splitter shifts’ 1,28 to compound shifts’ 1,30. As described earlier gear steps of crawler gears are larger: gear step C1-C2 is 1,67 and C2-1L 1,50. There is still problematic spur gear pair XS(8)-S(16) in sliding axle splitter but I don’t know other way to get suitable crawler ratio together with splitter’s step 1,28.

While this lego version is manual gearbox you need to pay more attention with splitter unit. In normal use only splitter’s positions high and low are used so operating is like basic 12-speed range-splitter transmission (2x3x2). For low speeds or high torque you choose splitter’s position crawler with main gearbox’s gears 1st, 2nd or reverse. Other note is that lego version doesn’t have standard H shift pattern but so called Y shift pattern. This is due to more compact main gearbox design. As conclusion about operating check carefully shift pattern in picture Ratios 14-speed, available crawler positions are marked as red.

This lego version is underdrive design for high speed lego motor. If you need direct drive version for low speed motor you can use main gearbox’s right axle under synchro axles as output instead of left one. Then scaled ratios become real ratios while underdrive auxiliary ratios and overdrive main gearbox ratio cancel each other.

Like in Volvo’s I-Shift also lego version has 13-speed and 12-speed conversions. In 13-speed version crawler gear ratio is different and splitter’s crawler position is only used with main gearbox’s gears 1st and reverse. There are still 6 reverse gears but ratios are partly different. In 12-speed version crawler gear pair is removed which gives two studs shorter design. Now you have only 4 reverse gears. Modifications are done in auxiliaries while main gearbox is identical in all versions.

Picture links:

13-speed conversion pic1

13-speed conversion pic2

13-speed conversion pic3

13-speed conversion pic4

13-speed conversion pic5

13-speed conversion pic6 (no bricks)

13-speed conversion pic7 (no bricks)

Picture links:

12-speed conversion pic1

12-speed conversion pic2

12-speed conversion pic3

12-speed conversion pic4

12-speed conversion pic5

12-speed conversion pic6 (no bricks)

12-speed conversion pic7 (no bricks)

Picture links:

Ratios 13-speed

lego 14-speed 4 into 13 rm.ldr

LDraw files:

lego 14-speed 4 into 12 rm.ldr

Available is also sequential sister transmission if you don’t have transmission driving rings. Check R.17. 14-speed truck version II in R. Sequential Transmissions.

For another severe duty transmission with extra slow crawler gears I recommend to check section G. 11-speed Transmissions inspired by Eaton Fuller 9ALL.

B. 12-speed Transmissions, 4 reverse gears:

These 12-speed transmissions contain 3-speed main gearbox with reverse gear plus range-change unit and splitter. So forward gears are 1L-1H-2L-2H-3L-3H-range_change-4L-4H-5L-5H-6L-6H in which L & H are splitter’s low and high. This kind of transmissions are quite common in trucking world: For example Mercedes, Scania and Volvo have their own designs. Also European trucks like DAF, Iveco, MAN and Renault can have 12-speed version of manual ZF Ecosplit, automated ZF AS Tronic or automated ZF TraXon. And American trucks can use 12-speed automated Eaton Endurant HD.

In lego designs version I is universal design (although inspired by Volvo & Scania) with some progression in gear steps. Version II is inspired by Eaton Endurant and for lego American trucks. But these are not all possibilities. For lego Scania you can check 12-speed conversion of A.3. 14-speed version III and for Volvo’s I-Shift 12-speed conversion of A.4. 14-speed version IV.

B.1. Version I, overall gear ratio 18,75:

Range + splitter + main gearbox (original setup)
Range + main gearbox + splitter (alternative setup)
Inspirer: Volvo and Scania trucks

This 12-speed transmission version I (version II of my 12-speeders) is inspired by Volvo and Scania but it’s more like basic lego design without accurate ratio set. It has the same design as the earlier 14-speed transmission version II, but the crawler gear is replaced with a reverse gear. Overall gear ratio is now good but gear steps still vary quite a lot. Luckily they vary in right direction so gear steps are progressive-like. Actually progression gives quite useful ratio set for heavy duty purposes while gear step between two top gears is smaller and overall gear ratio larger than in transmission based on geometrical gear steps. For splitter’s and range-change unit’s finished shift levers check YouTube video Building example.

Picture links:

Picture links:

12-speed ver2 alter pic1

12-speed ver2 alter pic2

12-speed ver2 alter pic3

12-speed ver2 alter pic4

12-speed ver2 alter pic5

LDraw files:

lego 12-speed ver2.ldr

lego 12-speed ver2 alter.ldr

Brickshelf Gallery:

12speed2

YouTube videos:

Available is also an alternative setup with several modifications: Splitter unit is synchromesh, overdrive and located parallel with main gearbox (left and middle transmission driving rings are for main gearbox and right one for splitter). Reverse gear is more compact but to get it I had to change slower ratio. These modifications haven’t changed gear steps or overall gear ratio so this is only alternative setup not new transmission. Main gearbox and splitter have interesting design while there is a shortcut from main gearbox’s input axle to splitter’s output axle via two clutch gears. This means that in splitter low gears 1L, 3L, 4L and 6L have less stages in power flow and better efficiency. For main gearbox’s shift lever use 6 studs long axle, put longitudinal bricks at the both ends and bush on the right side of the left brick. For splitter’s shift lever use axle pin with 3rd longitudinal brick on the right side and locate shift lever right next to middle brick. This way both shift levers are well supported. All in all this alternative setup is quite simple and compact design for low speed motor so it’s good choice for lego truck builders.

If you don’t like progression in gear steps and want geometrical gear steps instead check next B.2. 12-speed version II or 12-speed conversions of A.3. 14-speed version III and A.4. 14-speed version IV.

Ratio set of this 12-speed version I has also sister designs in my lego vehicles: Project 5590 II (page Project 5590) has sequential version and Lego 4x2 truck (page Vehicles) synchro version as an optional transmission.

Main gearboxes of this 12-speed version I can be used directly as 3+R-speed personal car transmission. On the other hand you can use main gearbox of P.17. Old 3-speed & transfer case version III (page Junkyard) together with splitters and range-change units of this chapter to get alternative 12-speed transmission.

B.2. Version II, overall gear ratio 19,69:

Main gearbox + splitter + range
Inspirer: Eaton Endurant HD

This 12-speed version II (version V of my all 12-speeders) is inspired by Eaton Endurant HD, 12-speed automated transmission. Design is same 2x3x2 but ratio set has geometrical gear steps like Endurant HD. And ratio sets of lego version and Eaton Endurant HD are quite close to each other, check picture Ratio comparison.

Picture links:

12-speed gearbox pic1

12-speed gearbox pic2

12-speed gearbox pic3

12-speed gearbox pic4

12-speed gearbox pic5

LDraw files:

lego 12-speed 5.ldr

Brickshelf Gallery:

12speed5

YouTube videos:

13-speed pic7 (no bricks)

Also this lego design has parallel mounted main gearbox and splitter which means that in some low split gears there is a shortcut in power flow between main gearbox and splitter via clutch gears. And to get shift levers for this parallel design check YouTube clip Building example, or description in previous version I with the difference that main gearbox and splitter are mirrored.

Eaton’s 12-speed Endurant HD and 18-speed Endurant XD are sister transmissions with identical main gearbox and range-change unit. Only difference is that HD has 2-speed splitter with larger gear steps while XD’s splitter is 3-speed with smaller gear steps. Also this lego version has sister design: for 18-speed big sister check chapter E.3. 18-speed version III.

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[Links & Notes]

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[G.-J.]

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[P.]

[Q.]

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[T.]

[U.]

C. 13-speed Transmissions:

Range/splitter + main gearbox
Inspirer: Eaton Fuller 13-speed transmission

The idea of this transmission is to get progressive gear steps (used in personal cars) available in truck transmission, in which range-change unit requires normally geometrical gear steps. In this case there is a large gear step between crawler (available in low range only) and 1st gear, and then there is a basic geometrical gear step in other low range gear pairs 1-2, 2-3 and 3-4. High range has gears 5-8 and they are splitted, so the number of gears is doubled and gear steps are halved in high range. Gears are: C-1-2-3-4-range_change-5L-5H-6L-6H-7L-7H-8L-8H.

13-speed version I is taken from my rear-engined Lego 4WD vehicle and version II is normal truck version of it. Best design so far is version III (truck design).

Note: Early versions have too large overall gear ratio, it should be 15-20. Reason of this exception is too slow crawler gear. Without crawler gear ratios and gear steps are pretty realistic.

C.1. My first version, rear engine 4WD, overall gear ratio 28,80:

Used in my Lego 4WD vehicle version 7

This construction is used in my Lego 4WD vehicle version 7 which is a rear engine solution. Check Vehicles to get more info.

Picture links:

Picture links:

Schematics

Auxiliary gearbox pic1 (no bricks)

Auxiliary gearbox pic2 (no bricks)

Auxiliary gearbox pic3 bricks

Main gearbox pic1 (no bricks)

Main gearbox pic2 (no bricks)

Main gearbox pic3 bricks

LDraw files:

lego 13-speed ver1.ldr

main 5-speed bricks.ldr

aux 3-speed bricks.ldr

Brickshelf Gallery:

13speed

YouTube videos:

Lego 13-speed upshifting

Main gearbox and auxiliary were earlier modeled separately but now is available whole transmission in one LDraw file.

C.2. Version II, 3 reverse gears, overall gear ratio 25,92:

Here is an alternative setup which is near to normal truck construction with front-mounted engine and rear-wheel drive. One possible problem in this setup is the height of the gearbox. Basic idea in this construction is that motor and auxiliary gearbox are above the front axle but the main gearbox is located under the driver’s cabin. If you need a lower gearbox construction, vertical flip in auxiliary gearbox helps a little, but it will locate motor higher.

Picture links:

13-speed gearbox ver2 pic1

13-speed gearbox ver2 pic2

13-speed gearbox ver2 pic3

13-speed gearbox ver2 pic4 (no bricks)

13-speed gearbox ver2 pic5 (no bricks)

LDraw files:

lego 13-speed ver2.ldr

Brickshelf Gallery:

13speed2

YouTube videos:

C.3. Version III, 3 reverse gears, overall gear ratio 20,57:

This 13-speed version III has some modifications compared to previous version II. Auxiliary gearbox is tried to make more compact so gear pairs take only 6 stud space between bricks. Main gearbox is changed from underdrive to direct drive version and gear step between crawler and first gear is smaller. This transmission is one good choice for gearbox builders.

Picture links:

13-speed gearbox ver3 pic1

13-speed gearbox ver3 pic2

13-speed gearbox ver3 pic3

13-speed gearbox ver3 pic4

13-speed gearbox ver3 pic5

LDraw files:

lego 13-speed ver3.ldr

Brickshelf Gallery:

13speed3

YouTube videos:

9-speed remake pic2 (shift pattern)

This 3-speed auxiliary has simple and compact design with good efficiency. Only problem is shifting to high split in high range due to S(16)-S(16) spur gear pair. Now is available also synchro version of this auxiliary. For more info check A.7. Auxiliary 3-speed gearbox, compound splitter/range-change unit on page Basic & special designs.

D. 9-speed Transmissions:

Here are 9-speed transmissions, which contain 4-speed main gearbox with crawler and reverse gear plus range-change unit. Forward gears are: C-1-2-3-4-range_change-5-6-7-8. Typical use for 9-speed transmission is mid-range or heavy duty truck itself without trailer. So total weights suit to middle-sized truck engines which has wider torque peak and speed range than larger engines. This means that larger gear steps of 9-speed transmission are not a problem. But higher total weights in truck and trailer use means you need larger engines and more gears with smaller steps to optimize performance.

Close ratio versions of 9-speeders are typically used in lighter hauling like delivery and wide ratio versions in vocational duties like dump trucks. To improve wide ratio versions’ performance in higher speeds they usually make top gear step 7-8 (also step 3-4 due to range-change unit) smaller than other steps or alternately slightly progressive gear steps in main gearbox. In lego designs version I has basic setup with geometrical gear steps and alternative ratio copy setup with slight progression. Also version II has now slight progression. Version III has significantly smaller top step 7-8. More info about this smaller top gear step is at the end of chapter O.10. 8-speed version II.

These lego transmissions are inspired by Eaton Fuller, ZF Ecomid, Volvo and Scania but at least also Mercedes has own designs of 9-speed transmissions.

D.1. Version I, 2 reverse gears, overall gear ratios 20,00 & 16,93:

Range + main gearbox
Inspirer: Eaton Fuller 9-speed B ratio (like RTX-14609B in Eaton Transmission Specifications Catalog)

9-speed transmission version I alternative setup

These 9-speed version I remake & alternative setup are inspired by older Eaton Fuller 9-speed transmissions and their large gear step B ratio set. So, these lego setups are wide ratio transmissions for trucks without trailer like dump trucks and other vocational duties, especially for lego American trucks. Remake is very simple and compact version with basic lego ratio set and alternative setup is larger and more complex ratio copy of 9-speed Fuller B ratio.

Picture links:

9-speed remake pic1

9-speed remake pic7 (no bricks)

9-speed remake overdrive

Picture links:

9-speed alter pic1

9-speed alter pic2 (shift pattern)

9-speed alter pic7 (no bricks)

9-speed alter pic8 (no bricks)

Picture links:

Ratios basic design

Ratios basic overdrive

Ratios alternative setup

lego 9-speed remake od.ldr

LDraw files:

lego 9-speed remake.ldr

lego 9-speed alter.ldr

Brickshelf Gallery:

9speedRemake

YouTube videos:

9-speed gearbox pic6 (no bricks)

Remake has several improvements compared to original version which is moved to page Junkyard if you want to check it. So, original underdrive version with sliding axle auxiliary is changed to full synchro direct drive version. As an optional overdrive version for low speed lego motor you can take output from right axle under synchro axles. Despite the new synchro auxiliary design is even shorter so this remake is the most compact inline setup in my heavy duty truck transmissions. With motor total length is still only 18 studs together with 8 stud width. Design is also modernized so it uses new 28 teeth double bevel gear instead of old 14 teeth thin bevel gears. This change also gives better ratio set although top step 7-8 (and step 3-4 due to range-change unit) is still too large 1,40 while in Fullers it’s 1,37 or less.

Alternative setup is longer and more complex design with lots of old 14 teeth thin bevel gears. But it’s very accurate ratio copy of Fuller’s design including slight progression in main gearbox, accurate step 1,37 (rare with legos) between two top gears and slightly slower reverse gear than crawler gear. You can check ratio and gear steps differences between lego setups and Fuller transmission from picture ratio comparison.

So, here is two setups for heavy duty trucks without trailer: remake is small and simple lego design and alternative setup has very accurate ratio set for reality seekers.

D.2. Version II, 1 reverse gear, overall gear ratio 12,60 REMAKE:

Main gearbox + range
Inspirer: ZF Ecomid & Eaton synchromesh 9-speed

Like previous 9-speed transmission also this version has 4-speed main gearbox with crawler and reverse gear plus range-change unit. New feature is that range change is integrated to main gearbox’s shift pattern. When you want to shift to high range you move shift lever far right over 3-4 line before you shift to desired gear. Shift to low range happens when shift lever is moved to R-C line. This way you can operate all the gears with only one shift lever. It also means that you can’t misuse crawler gear in high range or don’t have high reverse gear.

Picture links:	9-speed gearbox pic1	9-speed gearbox pic2	9-speed gearbox pic3	9-speed gearbox pic4	9-speed gearbox pic5

Picture links:	Shifters pic1	Shifters pic2	Complete transmission	Shift pattern

Picture links:	Ratios	Ratio comparison	Double H shift pattern

LDraw files:	lego 9-speed 2 remake.ldr

Brickshelf Gallery:	9speed2Remake

YouTube videos:	Building example (modified)

This lego design is remake with better ratio set and design. New ratio set is closer to ZF Ecomid with some progression but Eaton’s synchromesh 9-speed is not far away either. You can check differences from picture Ratio comparison. Lego design is improved so that both main gearbox and range-change unit are longitudinal and range change’s shifting system transfers transversal shift lever movement to longitudinal axle movement. Original design was problematical while it had geometrical wide ratio ratio set and transversal range-change unit. Also shifting system was not very optimized. But original design is still available on page Junkyard if you want to check it.

In real world this kind of range shifting system is called double H shift pattern. In low range shift lever centers itself to line 3-4 and in high range to line 5-6 which are not same line. This gives simple operating so that you tap shift lever right from line 3-4 to shift to high range and left from line 5-6 to shift to low range. So other gears in same range are in different direction than range change to minimize shifting errors. Double H shift pattern gives driver illusion that he/she shifts single 9-speed main gearbox although main gearbox is shifted through twice, first in low range and then in high range. With double H shift pattern you get very simple and logical operating but price is that you lose high range reverse gear.

D.3. Version III, 2 reverse gears, overall gear ratio 17,01:

Main gearbox + range
Inspirer: Volvo VT2009B & Scania GR905

Here is one more 9-speed transmission that has 4-speed main gearbox with crawler gear and range-change unit. There are also two reverse gears. This time main gearbox and range-change unit are located parallel. So this lego transmission is short and flat but wide. And if necessary you can still shorten this transmission by one stud: move most front Su(12)-Mu(20) gear pair inside frame behind synchro parts, there is enough space where bushes are.

Picture links:

LDraw files:

lego 9-speed 3.ldr

Brickshelf Gallery:

9speed3

YouTube videos:

Gear step 7-8 (also 3-4) is smaller than other steps of main gearbox and this feature is copied from Volvo’s and Scania’s transmissions. This smaller step makes transmission more usable in high speeds. More info about this is at the end of chapter O.10. 8-speed version II. On the other hand gear step C-1 is larger than main steps. Gear steps and overall gear ratio of lego version are close to Volvo’s transmission but ratios are all different while lego version is overdrive and Volvo’s transmission direct drive. Other notable thing is that how close Scania’s and Volvo’s ratios and gear steps are to each other. Check picture called Ratio comparison.

In lego version three transmission driving rings (synchro parts) on the left belong to main gearbox and the last one on the right is for range-change unit. It’s a little bit tricky to get shift levers for these gearboxes but here is how you can do it: First put longitudinal brick with holes between gearboxes and shift lever axles only half studs inside it. Then on the other end of the axles use bushes on the both sides of the longitudinal bricks. This way you can lock axles on their positions. I would have used horizontal shift lever for range-change unit but one of the low range’s axles is on the way so you couldn’t do it. For more compact design you can also try this: Use 8 studs axle for main gearbox’s shift lever and put bush on the right side of the left brick. This prevents axle to slide to left. On the right side use only brick without bushes. Then use axle pin for range-change unit’s shift lever and put 3rd brick on the right side of this range lever. While range lever is between two bricks it’s well supported. Range lever also prevents main gearbox’s shift lever axle to slide to right.

While input axle is supported by two technic brick 1x2 with 2 holes you may have difficulties to attach studded lego motor to the input axle. If you need hints to solve this problem check 4-speed version II in personal car transmissions.

E. 18-speed Transmissions:

In these 18-speed transmissions version I & version II are inspired by Eaton Fuller 18-speed manual transmission, professional extreme trucker’s only choice. This design is 2x4x2+2 meaning 4-speed main gearbox with crawler gear (C) plus splitter (L & H) and range-change unit, and altogether there are 4 reverse gears. So, forward gears are: CL-CH-1L-1H-2L-2H-3L-3H-4L-4H-range_change-5L-5H-6L-6H-7L-7H-8L-8H.

Version III is inspired by Eaton Endurant XD, automated 18-speed transmission. Its design is 2x3x3 meaning 3-speed main gearbox, 3-speed splitter and range-change unit, altogether you got 6 reverse gears. In lego version notation goes so that main gears in low range are 1-3 and in high range 4-6, and splitter gears are I-III.

E.1. Version I, 4 reverse gears, overall gear ratio 20,57:

Main gearbox + range + splitter
Inspirer: Eaton Fuller 18-speed transmission

As described earlier this lego version I is 2x4x2+2 design. It’s also underdrive version for high speed lego motor and old school version using 14 teeth thin bevel gears but without new 28 teeth double bevel gear or 20 teeth clutch gear.

Picture links:

18-speed gearbox pic5 (no bricks)

18-speed gearbox pic1

18-speed gearbox pic2

18-speed gearbox pic3

18-speed gearbox pic4

18-speed gearbox pic6 (no bricks)

LDraw files:

lego 18-speed remake.ldr

Brickshelf Gallery:

18speedRemake

YouTube videos:

18-speed gearbox pic6 (no bricks)

This lego version is remake in which parallel mounted range-change unit and splitter give shorter design, also shift levers are better placed giving better usability. Range-change unit is the only sliding axle design to maximize easy synchro shifts, but few sliding axle shifts should also be easier while there is double bevel gear in all range-change unit’s gear pairs. Original design is still available on page Junkyard if you want to check it.

E.2. Version II, 4 reverse gears, overall gear ratio 20,00:

Splitter + range + main gearbox
Inspirer: Eaton Fuller 18-speed transmission

Also this version II is 2x4x2+2 design and inspired by Eaton Fuller 18-speed manual transmission. This lego version is overdrive design for low speed lego motor. Parallel mounted splitter and range-change unit gives quite compact design with well placed shift levers. Also this version has synchro main gearbox and splitter and only range-change unit is sliding axle design. And range-change unit has double bevel gear in all gear pairs so shifting should be always easy in this lego transmission.

Picture links:

18-speed gearbox pic1

18-speed gearbox pic2

18-speed gearbox pic3

18-speed gearbox pic4

18-speed gearbox pic5

18-speed gearbox pic7 (no bricks)

Picture links:

LDraw files:

lego 18-speed 2.ldr

Brickshelf Gallery:

18speed2

YouTube videos:

This lego version mixes old school 14 teeth thin bevel gears and modern 28 teeth double bevel gear (ML, medium large in my notation). This mixing gives lego version quite accurate ratio set. Major difference is that lego version has only one overdrive gear while Eaton Fuller is double overdrive. Gear steps have minor differences like that lego version doesn’t have Fuller’s slight progression. You can check differences from picture Ratio comparison.

If you have 20 teeth double bevel clutch gear you can use it in reverse gear and take power directly to output axle via 20 teeth double bevel gear. This way you get rid of lower reverse gear axle and 8 teeth gears. Conversion doesn’t change ratios but gives simpler design with better efficiency.

E.3. Version III, 6 reverse gears, overall gear ratio 21,60:

Main gearbox + splitter + range
Inspirer: Eaton Endurant XD

This 18-speed version III is completely different kind of transmission: it’s 2x3x3 design inspired by Eaton Endurant XD, automated 18-speed transmission. While both main gearbox and splitter are 3-speed designs lego notation differs from versions I & II. Low range main gears are 1-3, high range main gears 4-6 and splitter gears I-III. This design also gives 6 reverse gears.

Picture links:

18-speed gearbox pic5 (shift levers)

18-speed gearbox pic1

18-speed gearbox pic2

18-speed gearbox pic3

18-speed gearbox pic4

LDraw files:

lego 18-speed 3.ldr

Brickshelf Gallery:

18speed3

YouTube videos:

In lego construction main gearbox is on the front right and range-change unit rear right. They are connected with long inline splitter on the left. Parallel design gives some shortcuts in power flow between main gearbox and splitter via clutch gears. Lego version’s ratio set is pretty realistic: major difference is that lego version has one overdrive gear but Eaton Endurant is double overdrive. Gear steps and overall gear ratio have only small differences. Endurant’s gear steps are all 1,19-1,20 while in lego version they vary between 1,16-1,22 but being mainly 1,20 due to splitter. You can check differences from picture Ratio comparison.

Building note: it’s not clearly shown in pictures but there are only two bricks per axle.

Eaton’s 12-speed Endurant HD and 18-speed Endurant XD are sister transmissions with identical main gearbox and range-change unit. Only difference is that HD has 2-speed splitter with larger gear steps while XD’s splitter is 3-speed with smaller gear steps. Also this lego version has sister design: for 12-speed little sister check chapter B.2. 12-speed version II.

F. 15-speed Transmissions, 3 reverse gears:

3-speed aux + main gearbox
Inspirer: Eaton Fuller Versatile 15-speed (like RT-14915 in Eaton Transmission Specifications Catalog)

These gearboxes are based on 10-speed transmission with 5-speed main gearbox and a range-change unit. In this case you have not only low and high range but also a deep reduction range. So you’ve got 10 road speeds and 5 deep reduction gears.

One notable thing is that low range (gears 1-5) and deep reduction range (gears L1-L5) overlap each other. In version I you shift two gears down in main gearbox when shifting from deep reduction range to low range (for example from gear L3 to 1st gear). Altogether you’ve got 13 progressive speeds. In versions II-IV and Eaton’s transmission you shift only one gear down in main gearbox when shifting from deep reduction range to low range so they have 12 progressive speeds.

And I recently found out that 15-speed Fullers have same ratio set in low and high range as older close ratio 10-speed Fullers. This relationship can be copied to these 15-speed lego designs and make 10-speed conversions by removing deep reduction range. 15-speed version III & IV have shorter 10-speed conversions as an example of these Eaton’s modular designs.

For lego builders I recommend version III as basic lego design and version IV as advanced ratio copy of real Fuller.

F.1. Version I, overall gear ratio 19,44:

Here is my original design. While it has quite long auxiliary gearbox I tried to rearrange auxiliary’s gear pairs and got alternative setup, which is 4 studs shorter. There is also complete shift lever for auxiliary. Only change in main gearbox is that front bearing point of first synchro axle is changed. While both versions have same gear pairs modification doesn’t affect to ratios or gear steps.

Picture links:

15-speed gearbox pic4 (no bricks)

15-speed gearbox pic1

15-speed gearbox pic2

15-speed gearbox pic3

15-speed gearbox pic5 (no bricks)

Picture links:

LDraw files:

lego 15-speed alter.ldr

Brickshelf Gallery:

15speed

YouTube videos:

In this version I & alternative setup you shift two gears down in main gearbox when shifting from deep reduction range to low range. So you have 13 progressive speeds. Check Jumps in picture Ratios to see all shifting possibilities.

F.2. Version II, overall gear ratio 16,67:

Also in this version II you have overlapping deep reduction and low range. Now you shift one gear down in main gearbox when shifting from deep reduction range to low range so you have 12 progressive speeds. Check Jumps in picture Ratios to see all shifting possibilities. Other modifications in this version II are synchromesh auxiliary and faster reverse gears.

Picture links:

15-speed gearbox pic1

15-speed gearbox pic2

15-speed gearbox pic3

15-speed gearbox pic4

15-speed gearbox pic5

LDraw files:

lego 15-speed 2.ldr

Brickshelf Gallery:

15speed2

YouTube videos:

Ratio comparison 15-speed

You may notice that auxiliary’s deep reduction range could be arranged simpler: first you take input from low range’s 16 teeth clutch gear to deep reduction clutch gear and then use Su(12)-Mu(20) gear pair to get in main gearbox’s input axle. Problem is that it gives gear step 1,67 which is same as in main gearbox so you will have some same ratios in deep reduction and low range. Present more complicated arrangement gives gear step 1,71 so some ratios in deep reduction and low range are close to each other but not same, just like in Eaton’s transmission.

Nowadays this 15-speed version II is not my best design, next modified versions III & IV has same ratio set except reverse gear but in smaller size.

F.3. Version III, overall gear ratio 16,67:

Also 10-speed conversion

10-speed Conversion Of 15-speed Version III

This 15-speed version III is upgrade for previous version II offering same ratio set with more compact construction. Auxiliary has now inline shift levers giving few studs more narrow gearbox and new reverse gear makes design one stud shorter. Price is that auxiliary needs two shift levers and slower reverse gear is less realistic for this transmission. Again design has 5x2+2=12 progressive speeds so you shift one main gear down when shifting from deep reduction range to low range.

Picture links:

Ratios 15-speed

15-speed gearbox pic1

15-speed gearbox pic2

15-speed gearbox pic3

15-speed gearbox pic4

Picture links:

Ratios 10-speed

10-speed conversion pic1

10-speed conversion pic2

10-speed conversion pic3

10-speed conversion pic4

LDraw files:

lego 15-speed 3.ldr

lego 15-speed 3 into 10.ldr

Brickshelf Gallery:

15speed3

YouTube videos:

Building example 10- & 15-speed

I found out some time ago that old close ratio 10-speed and 15-speed Fuller are sisters with one difference: 10-speed has shorter 2-speed auxiliary with low and high range and 15-speed 3-speed auxiliary with additional deep reduction range. Their ratio sets are identical except that additional deep reduction range. So here is also 10-speed lego conversion in which removed deep reduction range shortens design three studs. If you don’t have old 14 teeth thin bevel gears but new 28 teeth gear (ML, medium large in my notations) instead there is a simple modernization in auxiliary for 10-speeder without ratio changes: replace XS(8)-M(24) and Su(12)-Th(14) gear pairs with XS(8)-XS(8)-ML(28) gear train.

One notable thing in 15-speeder is that there is a long multi-piece axle from auxiliary to main gearbox. So it’s possible that it bends too much under high load and middle gear pairs lose their mesh. If problem occurs you can use same High torque kit as 15-speed version IV.

Basic lego design causes that gear steps vary quite a lot in these transmissions. But they are alternately too low and too high so in average ratios and overall gear ratio follow quite well real Eaton’s transmission. Check picture Ratio comparison (10-speed without deep reduction gears L1-L5 and RLL). So, here is two usable and realistic lego transmissions for older American trucks: simple and compact 10-speed or more versatile 15-speed.

F.4. Version IV, overall gear ratio 16,67:

Also 10-speed conversion

10-speed Conversion Of 15-speed Version IV

This 15-speed version IV is pretty much same as version III but with two improvements. Auxiliary is rearranged so shift lever of high and low range is closer to main gearbox. In main gearbox new gear pairs after synchro parts give that gear steps don’t vary so much as in version III. So you can say this is almost a ratio copy of real 15-speed Fuller, you can check differences between lego versions and real Fuller from picture Ratio comparison 15-speed.

Picture links:	15-speed gearbox pic1	15-speed gearbox pic2	15-speed gearbox pic3	15-speed gearbox pic4	15-speed gearbox pic5

Picture links:	10-speed conversion pic1	10-speed conversion pic2	10-speed conversion pic3	10-speed conversion pic4	10-speed conversion pic5

Picture links:	Ratios 15-speed	Ratios 10-speed	Ratio comparison 15-speed	High torque kit

LDraw files:	lego 15-speed 4.ldr	lego 15-speed 4 into 10.ldr

Brickshelf Gallery:	15speed4

YouTube videos:	Building example 10- & 15-speed

Again design has 5x2+2=12 progressive speeds so you shift one main gear down when shifting from deep reduction range to low range. For more info check Jumps in picture Ratios 15-speed. But main idea is to enjoy simple operating as 10-speed transmission on highway duties but when on/off highway versatility is needed you have slow gears offered by deep reduction range.

Also this 15-speed has 10-speed conversion that has no deep reduction range (gears L1-L5 & RLL). It suits to older trucks with linehaul or medium duties. This 10-speed is not so simple as previous 10-speed conversion but it’s still very compact and offers better and very realistic ratio set. Both lego conversion and older close ratio 10-speed Fuller are identical with 15-speeder’s low and high range so you can compare ratios from picture Ratio comparison 15-speed by ignoring gears L1-L5 & RLL.

Also this 15-speed has a long multi-piece axle from auxiliary to main gearbox. So under high load is possible that axle bends too much and middle gear pairs lose their mesh. If problem occurs check picture High torque kit for fine tuning.

F.5. More about 15-speed transmissions:

In real world 15-speed transmission is enlarged version of older 10-speed close ratio linehaul and medium duty transmission. 15-speed gives versatility for on/off highway situations by giving slow gears without losing small gear steps of close ratio 10-speed. This versatility comes handy when you need to drive slow and speed up and slow down very often. In certain speed changes you end up to change range all the time and 15-speed transmission prevents this range shifting in two ways. While 1st gear (in low range) is not slowest gear you can have smaller gear steps and overall gear ratio so low range is faster than in wider ratio 10-speed transmission. So you can drive a little bit faster without changing to high range. Other thing is overlapping deep reduction and low range so there is a large speed range where you can choose either deep reduction or low range. In very rough situations you can drive with deep reduction range and on easier terrains with low range and have lots of speed changes without need to change range.

On the other hand, if you can skip gears you there is a completely different approach you can try. You can do easy button shifts without using main shift lever by shifting between low and deep reduction range (for example L3-3). If you can use this larger gear step and need only two gears there is quite large speed range where you don’t need to shift main gearbox at all: just choose suitable move off gear in deep reduction range and drive with same main gear in low range.

Three ranges give also three reverse gears: two slow and one very fast. Eaton’s modern 10-speed transmissions has also very fast high range reverse gear but in 15-speed transmission (and older close ratio 10-speed) high reverse is even faster.

Too complicated? Here is simplified using idea:
-On highway 10 speeds with low range (gears 1-5) and high range (gears 6-10) with simple operating
-Off highway 5 speeds with deep reduction range (gears L1-L5)

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G. 11-speed Transmissions (4x2+3), 3 reverse gears:

3-speed aux + main gearbox
Inspirer: Eaton Fuller 9ALL

These gearboxes have 8 road speeds and 3 deep reduction gears for extra low speed driving. They are based on the 9-speed transmission which has 8 speeds plus a crawler gear. Now auxiliary gearbox is not a 2-speed range-change unit but a 3-speed construction: high range, low range and deep reduction range. When you choose 1st gear or crawler gear with deep reduction range you’ve got two extra crawler gears. Altogether these severe duty gearboxes have very large overall gear ratio. Forward gears are: LL1-Lo-LL2-1-2-3-4-5-6-7-8.

Best lego design to build so far is version III. For another severe duty transmission with extra slow gears I recommend to check A.4. 14-speed transmission version IV inspired by Volvo I-Shift with crawler gears.

G.1. Version I, overall gear ratio 36,00:

Here is version I of 11-speed transmissions. It’s underdrive design for high speed lego motor.

Picture links:

11-speed gearbox pic4 (no bricks)

11-speed gearbox pic1

11-speed gearbox pic2

11-speed gearbox pic3

11-speed gearbox pic5 (no bricks)

LDraw files:

lego 11-speed.ldr

Brickshelf Gallery:

11speed

YouTube videos:

When comparing to real Eaton Fuller 9ALL this lego version has too slow reverse gears and top gear step 7-8 is too large 1,43, largest gear step between two top gears in Fuller transmissions is 1,37.

G.2. Version II, overall gear ratio 37,50:

11-speed Transmission Alternative Version II

This version II has 3 modifications compared to version I: range-change unit is now sliding axle solution with slightly slower deep reduction range, main gearbox is changed from underdrive to direct drive and reverse gears are a little bit faster. So, reverse gears have now more realistic ratios but top gear step 7-8 is still too large 1,43.

Picture links:

11-speed gearbox alter pic1

11-speed gearbox alter pic2

11-speed gearbox alter pic3

11-speed gearbox alter pic4

11-speed gearbox alter pic5

11-speed gearbox alter pic6

LDraw files:

lego 11-speed 2 alter.ldr

Brickshelf Gallery:

11speed2

YouTube videos:

Here is shown only alternative setup. Its auxiliary is more compact than in original version and double bevel type gear wheel in all sliding axle gear pairs gives easier auxiliary shifting. Original auxiliary has problematic XS(8)-S(16) spur gears so it’s not easy to shift. So original design is moved to page Junkyard if you want to check it.

G.3. Version III, overall gear ratio 37,50:

Auxiliary in this modernized version III combines synchro shifts from version I and ratios from version II. In main gearbox thin 14 teeth bevel gears are replaced with new 28 teeth gear (ML, medium large in my notations). This replacement gives lego version more realistic ratio set although top gear step 7-8 is still too large 1,40, it shouldn’t be over 1,37.

Picture links:

11-speed gearbox pic1

11-speed gearbox pic2

11-speed gearbox pic3

11-speed gearbox pic4

11-speed gearbox pic5

LDraw files:

lego 11-speed 3.ldr

Brickshelf Gallery:

11speed3

YouTube videos:

One notable thing is that lego version is direct drive but Fuller 9ALL is overdrive. But if you change output from middle lower axle to right lower axle you get overdrive lego design. But then I recommend to test efficiency of reverse gears while their gear wheels will have significant overdrive situation after synchro parts.

If you need severe duty transmission with extra slow gears for your lego American truck I recommend to build this 11-speed version III.

H. 10-speed Transmissions (4x2+2), 3 reverse gears:

Inspirer: Eaton Fuller 8LL

These are not the ordinary 10-speed transmissions with 5-speed main gearbox and range-change unit, those are introduced in next section I. 10-speed Transmissions (5x2). So these gearboxes contain 8 road speeds and 2 deep reduction gears for low speed driving (4x2+2-structure). They are based on the 9-speed transmission which has 8 speeds plus a crawler gear. Like in 11-speed transmission auxiliary gearbox is 3-speed construction: high range, low range and deep reduction range. When you choose crawler gear with deep reduction range you’ve got one extra crawler gear. It gives you also the 3rd reverse gear. Forward gears are: LL-Lo-1-2-3-4-5-6-7-8.

H.1. Version I, overall gear ratio 24,00:

3-speed aux + main gearbox

Here is version I of this type of transmission (version II of all 10-speeders). This version has same auxiliary as 11-speed version I and also gear steps of main gearbox are same except crawler gear. So compared to Eaton’s transmission this lego version has larger overall gear ratio due to larger steps in main gears.

Picture links:

10-speed gearbox ver2 pic1

10-speed gearbox ver2 pic2

10-speed gearbox ver2 pic3

10-speed gearbox ver2 pic4 (no bricks)

10-speed gearbox ver2 pic5 (no bricks)

10-speed gearbox ver2 pic6 (no bricks)

LDraw files:

lego 10-speed 2.ldr

Brickshelf Gallery:

10speed2

While auxiliary is same as in 11-speed version I you can also copy auxiliary of 11-speed version II alternative setup to be used with this main gearbox and get another 10-speed transmission with 2 crawler gears. This modification changes ratio of gear LL to 25,00 and gear step LL-Lo to 1,56.

H.2. Version II, overall gear ratio 19,44:

Main gearbox + 3-speed aux

In this version II (version VI of all 10-speeders) ratios, gear steps and overall gear ratio are closer to Eaton’s transmission than in my version I. So now 8 road gears have smaller gear steps but crawler gears have larger steps. Check picture Ratio comparison. Other change between these lego versions is that auxiliary gears are now together in one shift pattern but don’t think this as a twin stick transmission.

Picture links:

10-speed gearbox ver6 pic1

10-speed gearbox ver6 pic2

10-speed gearbox ver6 pic3

10-speed gearbox ver6 pic4

10-speed gearbox ver6 pic5 (no bricks)

10-speed gearbox ver6 pic6 (no bricks)

LDraw files:

lego 10-speed 6.ldr

Brickshelf Gallery:

10speed6

YouTube videos:

While in lego version input axle is supported by two technic brick 1x2 with 2 holes you may have difficulties to attach studded lego motor to the input axle. If you need hints to solve this problem check 4-speed version II in personal car transmissions.

You may first think about this kind of 10-speed transmission that 3rd range giving only 2 gears is just wasting gears. But in closer look this 4x2+2-structure is not so bad at all. While there are 2 independent crawler gears in this transmission gear steps LL-Lo and Lo-1 can be chosen larger than other steps. So compared to basic 10-speed transmission (5x2-structure) this version can have larger overall gear ratio together with smaller gear steps in road gears which makes this transmission more usable. Also 3 reverse gears is a benefit especially when there is smaller gear step between low and high range reverse gears than in 5x2-structure. But price is that 4x2+2-stucture is more complex, longer and heavier than 5x2-structure.

I. 10-speed Transmissions (5x2), 2 reverse gears:

These 10-speed transmissions are a quite simple constructions containing only 5-speed main gearbox with reverse gear plus 2-speed range-change unit. Forward gears are simply: 1-2-3-4-5-range_change-6-7-8-9-10. So this design is the simplest and most logical truck transmission to operate.

But it wasn’t easy to get lego versions with realistic ratios while I first knew only B and C ratio sets of today’s manual Eaton Fuller. So every time you matched lego main gearbox and range-change unit overall gear ratio was too small or too high. It took some time before I got ready realistic lego version of B ratio set, it’s version III. Then I found older Scania’s 10-speed design with smaller overall gear ratio than modern Fullers. It was easier to get with legos, check version IV. Later I found S ratio set of automated 10-speed Eaton Fuller in which top gear step 9-10 (and step 4-5 due to range-change unit) is significantly smaller than other steps. It’s easier to design with legos so there are remade version I & version II. Version V is inspired by B ratio set of Fuller Advantage Series manual transmission and its automated sister and version VI is inspired C ratio set of same Fuller transmission. The best lego design so far is version V alternative setup but after two remakes all these six lego versions are realistic designs to build.

And if overall gear ratio under 10,00 is enough as an extra you can check simple and compact 10-speed conversions of F.3. 15-speed version III & F.4. 15-speed version IV. They are inspired by older 10-speed Fullers that had smaller gear steps and overall gear ratio than modern versions. That older Fuller had more versatile 15-speed big brother in which auxiliary was 3-speed design with additional deep reduction range.

You may also think that 10-speed transmission with range-change unit would be mother of all truck transmissions but they are not very common, I have found only Eaton’s and Scania’s versions. More common is 9-speed transmission that has 8 road speeds plus crawler gear.

I.1. Version I, overall gear ratio 17,86:

Main gearbox + range
Inspirer: Eaton Fuller Smart Advantage S ratio (like FAO-16810S-EP3 in Eaton Transmission Specifications Catalog)

First solution for gearbox matching was that gear steps were mainly 1,39-1,43 but gear steps 3-4 and 8-9 were only 1,26. In reality smallest step should be 4-5 and 9-10 and I thought gear steps shouldn’t vary so much. But I found later Eaton Fuller Smart Advantage which is automated 10-speed transmission together with Cummins engine. In its S ratio set gear step 9-10 (and 4-5 due to range-change unit) significantly smaller than other steps to give better performance in high speeds.

Picture links:

10-speed gearbox pic1

10-speed gearbox pic2

10-speed gearbox pic3

10-speed gearbox pic4

10-speed gearbox pic5

LDraw files:

lego 10-speed remake.ldr

Brickshelf Gallery:

10speedRemake

YouTube videos:

So I decided to replace old version I with new design that follows that Fuller Smart Advantage design. In new lego design gear steps are mainly 1,40-1,43 but steps 4-5 and 9-10 are only 1,25. So gear steps are now much more realistic than in old design. If you want to check old version I it’s moved to page Junkyard.

For alternative range shift lever locking with rubber belt check YouTube video Building example.

One notable thing in this new lego design is large amount of 14 teeth bevel gears. If it becomes a problem I recommend to check next version II remake, which is modernized version of this remake design.

I.2. Version II, overall gear ratio 18,00:

Main gearbox + range
Inspirer: Eaton Fuller Smart Advantage S ratio (like FAO-16810S-EP3 in Eaton Transmission Specifications Catalog)

This version II (version IV of my all 10-speeders) is another remake that is inspired by Eaton Fuller Smart Advantage, automated 10-speed transmission together with Cummins engine. New lego design follows Eaton’s S ratio set where gear step 9-10 (and 4-5 due to range-change unit) is significantly smaller than other steps to give better performance in high speeds. Original version II had some ratio reality problems and not very optimized range-change unit so it’s now located to page Junkyard if you want to check it.

Picture links:

10-speed gearbox ver4 pic1

10-speed gearbox ver4 pic2

10-speed gearbox ver4 pic3

10-speed gearbox ver4 pic4

10-speed gearbox ver4 pic5

LDraw files:

lego 10-speed 4 remake.ldr

Brickshelf Gallery:

10speed4Remake

YouTube videos:

For alternative range shift lever locking with rubber belt check YouTube video Building example.

This version II remake is a modernized version of previous version I remake: It doesn’t use any of 14 teeth thin bevel gears and contains one new 28 teeth gear wheel (in my notations ML, medium large). Design has brick frame but it can be built directly with studless frame.

I.3. Version III, overall gear ratio 15,00:

Main gearbox + range
Inspirer: Eaton Fuller FR-10B

10-speed Transmission Alternative Version V

Finally I found how to build 10-speed transmission with range-change unit that has good gear steps combined to good overall gear ratio, so here is version III (version V of all 10-speeders). Gear steps vary between 1,33, 1,35 and 1,39 but that is acceptable while largest gear step is between main gearbox’s 2 slowest gears. Ratios of reverse gears are a little bit slower than ratios of 1st and 6th forward gears, another feature taken from inspirer. This version III is overdrive gearbox and overall gear ratio is close to ratio series B in 10-speed Eaton Fuller.

Picture links:

10-speed gearbox ver5 pic1

10-speed gearbox ver5 pic2

10-speed gearbox ver5 pic3

10-speed gearbox ver5 pic4

10-speed gearbox ver5 pic5

Picture links:

10-speed ver5 alter pic5 (no bricks)

10-speed ver5 alter pic1

10-speed ver5 alter pic2

10-speed ver5 alter pic3

10-speed ver5 alter pic4

10-speed ver5 alter pic6 (no bricks)

LDraw files:

lego 10-speed 5.ldr

lego 10-speed 5 alter.ldr

Brickshelf Gallery:

10speed5

YouTube videos:

Available is also alternative setup in which gearboxes are located parallel to get shorter transmission. It’s interesting design while in high range gears 7 and 9 power flow has shortcut from main gearbox’s clutch gear to auxiliary’s clutch gear and output axle. So these gears have good efficiency. For main shift lever use 2 longitudinal bricks and 8 stud axle and put bush on the right side of left brick. For range shift lever use axle pin and 3rd brick on the right side of it. With this combination both shift levers are well supported. All in all this alternative setup is quite compact design if width doesn’t become a problem.

I.4. Version IV, overall gear ratio 13,71:

Range + main gearbox
Inspirer: Scania GR871

This version IV (version VII of my all 10-speed transmissions) is inspired by Scania GR871. Major difference to Eaton’s modern transmissions is that Scania’s transmission has smaller overall gear ratio. This helped lego designing a lot so this lego version has very good geometrical gear steps, just like Scania’s transmission. Gear steps and overall gear ratio between lego version and Scania’s transmission are also close to each other but ratios are all different while lego version is overdrive and Scania’s transmission direct drive. Check picture Ratio comparison.

Picture links:

10-speed gearbox ver7 pic1

10-speed gearbox ver7 pic2

10-speed gearbox ver7 pic3

10-speed gearbox ver7 pic4

10-speed gearbox ver7 pic5

10-speed gearbox ver7 pic6

LDraw files:

lego 10-speed 7.ldr

Brickshelf Gallery:

10speed7

YouTube videos:

10-speed gearbox ver8 pic1

This lego version has several independent axles located coaxial so check structure carefully that you don’t replace two coaxial axles with single one. Every axle is supported by two bricks so if you see four bricks on one axle line there are two separate axles in structure.

If you are looking for 10-speed lego transmission that suits to low speed motor and linehaul truck plus has quite compact design and good geometrical gear steps here is your choice.

If you don’t have old 14 teeth thin bevel gears there is a simple conversion using new 28 teeth gear (medium large ML in my notations). Move both range-change unit’s lower axles half studs away from each other and replace front Th(14)-Mu(20) gear pair with Mu(20)-ML(28) gear pair. This leads to minor ratio changes in lower range but still keeps design very realistic.

I.5. Version V, overall gear ratio 15,56:

Original setup: main gearbox + range
Alternative setup: range + main gearbox
Inspirer: Eaton Fuller Advantage Series B ratio

This version V (version VIII of my all 10-speed transmissions) is inspired by 10-speed B ratio Eaton Fuller Advantage Series manual transmission and its automated sister Eaton Fuller UltraShift PLUS LAS 10B. Reason for these inspirers is that range step is larger and reverse gear slower than in manual FR Series. In lego transmission these ratio changes allowed shorter range-change unit and simpler reverse gear design when main gearbox’s output axle is directly under synchro axle. All in all lego ratio set is quite close to inspirer’s except that lego version is overdrive and Fuller’s 10-speed B ratio set direct drive, check picture Ratio comparison.

Picture links:

10-speed gearbox ver8 pic2

10-speed gearbox ver8 pic3

10-speed gearbox ver8 pic4

10-speed gearbox ver8 pic5

10-speed gearbox ver8 pic6

10-speed gearbox ver8 pic7 (no bricks)

Picture links:

10-speed ver8 alter pic1

10-speed ver8 alter pic2

10-speed ver8 alter pic3

10-speed ver8 alter pic4

10-speed ver8 alter pic5

10-speed ver8 alter pic6 (no bricks)

Picture links:

LDraw files:

lego 10-speed 8 alter.ldr

Brickshelf Gallery:

10speed8

YouTube videos:

10-speed gearbox ver11 pic1 (shift pattern)

Now available is two setups: original setup is quite basic lego design without special optimization but alternative setup is squeezed three studs shorter by swapping main gearbox and range-change unit. So, motor included alternative setup is only 20 studs long and eight studs wide.

This lego 10-speed version V is sister design of earlier version III. Main gearboxes have different designs but ratios are identical except reverse gear. Version III is old school design with 14 teeth thin bevel gears but without new 20 teeth clutch gear or new 28 teeth double bevel gear. This version V is modernized design using those new gear wheels but without 14 teeth gears. Main gearboxes and range-change units are fully exchangeable between these lego versions.

If you prefer simple truck transmission to operate 10-speed with range-change unit is your choice and this lego version V alternative setup is so far the best I can offer.

I.6. Version VI, overall gear ratio 17,99 NEW:

Main gearbox + range
Inspirer: Eaton Fuller Advantage Series C ratio

This version VI (version XI of my all 10-speed transmissions) is inspired by 10-speed C ratio Eaton Fuller Advantage Series manual transmission and its automated sister Eaton Fuller UltraShift PLUS LAS 10C. It’s wide ratio version for linehaul semitrailer trucks. Larger overall gear ratio gives better move off and climbing capability but larger gear steps don’t suit to heavy duty trucks with larger truck engines.

Picture links:

10-speed gearbox ver11 pic2

10-speed gearbox ver11 pic3

10-speed gearbox ver11 pic4

10-speed gearbox ver11 pic5 (no bricks)

10-speed gearbox ver11 pic6 (no bricks)

Picture links:

LDraw files:

lego 10-speed 11.ldr

Brickshelf Gallery:

10speed11

YouTube videos:

But this lego design was almost an eternity on my drawing board while this ratio set is very difficult to build with lego. Ratio set is very close to Fuller’s one, main difference is that lego range step is 5,00 and Fuller’s 4,90. This leads to lego version’s slightly higher ratios in low range and larger overall gear ratio. You can check differences from picture Ratio comparison. Copying Fuller’s ratio set also leads to very good geometrical gear steps while steps only vary between 1,37-1,39.

So, if you fancy to be American linehaul trucker, want accurate but complex and rare lego ratio set and prefer simple operating of 10-speed transmission here is design for you. :-)

J. Transmissions With 3- & 4-speed Splitter:

Waits update...

This section contains truck transmissions that have 3- or 4-speed splitter. Common feature in lego designs is rotary shift splitter, done by lego part technic changeover rotary catch.

12-speed twin splitter is inspired by Eaton’s transmission and contains 4-speed main gearbox with reverse gear plus 3-speed splitter.

20-, 14-, 16- & 18-speed are all inspired by Spicer Airshift transmissions which are all based on 5-speed main gearbox with reverse gear plus 4-speed splitter. Designs alternate so that some main gears have only two splitter positions available. This means that upshifting procedure and ratio set vary quite a lot between these transmissions. So check first current transmission’s shift pattern in picture Ratios before using. (Not updated yet...)

J.1. 12-speed Twin Splitter, 3 reverse gears, overall gear ratio 12,50:

Main gearbox + splitter
Inspirer: Eaton Twin Splitter

This transmission has 4-speed main gearbox with reverse gear plus 3-speed splitter unit. Notation goes so that main gears are 1-4 and splitter gears I-III. Lego design is modernized remake with improved splitter: Its ratios are now under/direct/over so ratio set is more realistic (no more underdrive design). And sliding axle design is replaced with synchro version that has sequential rotary shifting. As an upgrade it’s possible to add motor operated remote control for splitter especially if you know how to build 90 degree stepper.

Picture links:

12-speed Twin Splitter pic1

12-speed Twin Splitter pic2

12-speed Twin Splitter pic3

12-speed Twin Splitter pic4

12-speed Twin Splitter pic5

12-speed Twin Splitter pic6 (no bricks)

12-speed Twin Splitter pic7 (no bricks)

LDraw files:

lego 12-speed ts remake.ldr

Brickshelf Gallery:

12speed3Remake

YouTube videos:

20-speed splitter shifter

Modernization means that you will need technic changeover rotary catch, new 20 teeth double bevel clutch gear, axle joiner 3L and transmission driving ring 3L. These give lego transmission more realistic ratio set and better usability while you get rid of spur gear sliding axle shifting. If you don’t have these new lego parts older original and alternative setups are still available on page Junkyard.

There is also a sequential sister transmission, for more info you can check R.14. 12-speed Twin Splitter truck.

The idea in real twin splitter transmission is that you don’t have to shift main gearbox often, most of the shifts are easy splitter shifts. Top three gears cover quite large speed area, so you need only splitter shifts from higher city speed limits to highway speeds. On the other hand, skipping gears is more difficult than in transmission with 2-speed splitter. If you shift only with main gearbox there is a huge gear step, which is usable only in low gears with unloaded truck or in downshifting. In other situations you have to shift with splitter even if you skip gears.

I’m not sure why it’s called twin splitter, but here is two guesses. 1) You have two splitter units, the first one is underdrive/direct drive and the second one direct drive/overdrive. When you put these two together, you don’t need two direct gears. So, altogether you’ve got two splitters and three speeds => twin splitter. 2) Name can also come from transmission’s design because it’s 12-speed twin countershaft splitter transmission.

J.2. 20- & 14-speed Spicer, 4 reverse gears, overall gear ratios 19,59 & 15,43:

Inspirers: Spicer HD 20-speed 1420 & Spicer HD 14-speed 1214 (Service Manual)

These lego transmissions are inspired by 20- and 14-speed Spicer transmissions which are based on 5-speed main gearbox with reverse gear plus 4-speed splitter. But their using and ratio sets are completely different.

Picture links:

20-speed shift pattern

Picture links:

14-speed splitter shifter

14-speed shift pattern

Picture links:

Ratios 20-speed

Ratios 14-speed

LDraw files:

spicer 20-speed transm.ldr

spicer 14-speed transm.ldr

Brickshelf Gallery:

Spicer20and14

YouTube videos:

Building example 20-speed

Building example 14-speed

20-speed is actually more like two 10-speed splitter transmissions for heavy duty truck: splitter’s positions 1 & 2 are low and high split for off highway driving and positions 3 & 4 are low and high split for on highway driving. So you have 10 off highway gears, 10 on highway gears and 4 reverse gears. If you start with 1st off highway gear, go through splitter’s all 4 positions when main gearbox stays in 1st gear and then continue on highway upshifting procedure you get altogether 12 progressive gears. This procedure is for on highway driving with heavy loads.

14-speed has same kind of 5-speed main gearbox and 4-speed splitter but in main gears 1-3 only splitter positions 1-2 are used. In reverse and high speed main gears 4-5 all splitter positions 1-4 are available. When used as described there is some progression in compound shifts to enlarge overall gear ratio. This 14-speed gives easy splitter shifts in high speeds while eight top gears need only one main gearbox shift.

Both splitters have sequential rotary shifting with help of lego part technic changeover rotary catch. Splitter’s shifter tries to imitate real Spicer’s airshift switch mounted to main shift lever. But lego splitter can be also equipped with motor operated remote shifting instead, especially if you know how to build small 90 degree stepper.

Using these transmissions is a little bit complicated so I recommend to check ratios and shift pattern carefully before use.

J.3. (reserved for 16- & 18-speed Spicer)

reserved for two Spicer transmissions, 5-speed main gearbox & 4-speed splitter, some main gears have two splitter positions only...

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K. 16-speed Transmissions, 4 reverse gears:

16-speed transmission is the most effective way to get lots of gears in truck transmissions. Every main gearbox’s gear can be used in low and high range, also every gear can be splitted with splitter unit. Main gearbox has only 4 gears and a reverse gear, but altogether you’ve got 16 forward gears and 4 reverse gears. Forward gears are: 1L-1H-2L-2H-3L-3H-4L-4H-range_change-5L-5H-6L-6H-7L-7H-8L-8H.

ZF Ecosplit is the best known 16-speed transmission but also Mercedes and older Volvos have 16-speed transmissions. I don’t count Eaton’s design as genuine 16-speed transmission while it’s actually automated 18-speed transmission without overdrive gears 8L and 8H. Eaton doesn’t advertise this fact but larger 1,44 gear step in shift 2-3 reveals the truth, it’s 18-speeder’s shift CH-1L.

16-speed ZF Ecosplit inspired transmission is also in my Lego 4x2 truck 16-speed, page Vehicles.

K.1. Version I, overall gear ratio 15,43:

Range + splitter + main gearbox
Inspirer: ZF Ecosplit

This 16-speed version I is inspired by famous ZF Ecosplit. But it means that lego range-change unit and main gearbox are a little bit more complicated to get suitable overall gear ratio. Available is two lego setups. Old original setup is underdrive and suits best to high speed motor while new alternative setup is overdrive and for low speed motor. Gear steps and overall gear ratio are identical in these setups but reverse gears have some difference: in original setup reverse gears are slower than 1st and 5th forward gears but in alternative setup faster.

Picture links:

16-speed gearbox pic1

16-speed gearbox pic2

16-speed gearbox pic3

16-speed gearbox pic4 (no bricks)

16-speed gearbox pic5 (no bricks)

16-speed gearbox pic6 (no bricks)

Picture links:

16-speed alter pic7 (no bricks)

16-speed alter pic8 shifters

Picture links:

Ratio comparison alter

LDraw files:

lego 16-speed.ldr

lego 16-speed alter.ldr

Brickshelf Gallery:

16speed

16speedBuild

YouTube videos:

After making pictures I found possible problem in alternative setup: reverse gear’s M(24)-Mu(20) gear pair has weak mesh so it can lose contact under high load. If this problem occurs you have to relocate XS(8)-M(24)-Mu(20) gear wheels next to bricks by moving other main gearbox’s front gear pairs one stud forward. This conversion is done in updated LDraw file and YouTube video Building example alter.

There is also a ratio comparison between alternative lego setup and overdrive version of real ZF Ecosplit. Major difference is that ZF’s range-change unit has larger step than lego version, otherwise ratios and gear steps are very close to each other.

If you don’t have transmission driving rings available is also sequential sister design. Check 16-speed truck in section R. Sequential Transmissions.

One notable thing is that in ZF Ecosplit high range reverse gears are not mentioned in shift pattern or brochures. If you have double H shift pattern version high range reverse gears are not available at all. And in single H shift pattern 16-speed gearbox high range reverse gears are too fast to move off, so you need to start with low range and do difficult (large gear step) range change to get fast reverse gears. Non synchro reverse gear complicates job even more. But in lego version high range reverse gears can be used while you can move off with every gear. Actually you don’t even need reverse gears in lego gearbox while motor works in both directions.

K.2. Version II, overall gear ratio 13,71:

Range + main gearbox + splitter
Inspirer: Volvo SR62

This 16-speed version II uses simpler gear pairs than previous version I and it leads to partly smaller gear steps and smaller overall gear ratio. When comparing them to real world’s transmissions closest inspirer is Volvo’s old SR62. When compared to my earlier lego designs closest is 18-speed transmission without crawler gears.

Picture links:

16-speed gearbox pic1

16-speed gearbox pic2

16-speed gearbox pic3

16-speed gearbox pic4

16-speed gearbox pic5

LDraw files:

lego 16-speed ver2.ldr

Brickshelf Gallery:

16speed2

YouTube videos:

16-speed gearbox pic7 (no bricks)

Range-change unit’s shift lever is locked by rubber belt. For shifting tilt lever slightly to right to unlock it and pull or push lever into new position.

Main gearbox and splitter are located parallel with special design: There is a shortcut from main gearbox’s synchro axle to splitter’s output axle via two clutch gears when main gearbox’s gears 2 or 4 are selected with high split. So gears 2H, 4H, 6H and 8H have less stages in powerflow and better efficiency. When building this transmission note that three synchro axles on the left belong to main gearbox and the last one on the right is splitter’s axle. For main gearbox’s shift lever use 8 studs long axle, put longitudinal bricks at the both ends and bush on the right side of the left brick. For splitter’s shift lever use axle pin with 3rd longitudinal brick on the right side and locate shift lever right next to middle brick. This way both shift levers are well supported.

If you don’t have old 14 teeth thin bevel gears you can do simple conversion with new 28 teeth gear (medium large ML in my notations). In main gearbox move left axle under synchro axles one stud to left and replace rear Th(14)-Mu(20) gear pair with Mu(20)-ML(28) gear pair. This leads to minor changes in ratios, gear steps and overall gear ratio but keeps design still realistic.

This transmission has sister transmission E.2. Small step 16-speed for linehaul truck in section E. Flat Gearbox Designs on page Basic & special designs.

K.3. Version III, overall gear ratio 15,75:

Main gearbox + range + splitter
Inspirer: ZF Ecosplit

This 16-speed version III is also inspired by ZF Ecosplit and is some kind of upgrade of earlier 16-speed version I. This time design is direct drive so it suits to both low and high speed lego motors.

Picture links:

16-speed gearbox pic1

16-speed gearbox pic2

16-speed gearbox pic3

16-speed gearbox pic4

16-speed gearbox pic5

16-speed gearbox pic6

Picture links:

LDraw files:

lego 16-speed ver3.ldr

Brickshelf Gallery:

16speed3

YouTube videos:

So, this lego design has some improvements compared to version I. First change is that splitter is synchro version and range-change unit sliding axle design. This change is to minimize sliding axle shifts. Range-change unit has also double bevel gear in all gear pairs to ensure easier shifts than in design that has also spur gear gear pairs. Range step is also larger 4,38 which gives lego design more accurate ratio set compared to real ZF Ecosplit. Actually lego range step 4,50 would be closer to ZF’s range step 4,57, but it would lead either underdrive design or less usable spur gear gear pair in range-change unit so I abandoned it. You can check ratio set differences between lego version and ZF Ecosplit from picture Ratio comparison. Other improvement is that range-change unit and splitter are fully parallel which leads to slightly shorter design.

So, if you have both old 14 teeth thin bevel gears and new 28 teeth double bevel gear (ML, medium large in my notations) here is my best lego version of ZF Ecosplit. For lego European trucks like DAF, Iveco, MAN or Renault this transmission is your choice. But if you don’t have transmission driving rings available is also sequential sister design. Check 16-speed truck in section R. Sequential Transmissions.

L. Basic Designs With Splitter:

These are basic lego transmissions in which main gearboxes use basic XS(8)-M(24) gear pairs before synchro parts and Su(12)-Mu(20) gear pair after them. 10-speed version has 5-speed main gearbox with reverse gear plus splitter and 12-speed 6-speed main gearbox plus splitter. Splitter unit has several different designs but splitter step is always 1,33. But all splitter steps between 1,25-1,33 are usable with these designs. Smaller splitter step gives better performance in high speeds due to smaller step between two top gears but it also reduces overall gear ratio and makes gear steps vary more.

L.1. 10-speed, 2 reverse gears, overall gear ratio 12,00:

Splitter + main gearbox

This basic 10-speed is version X of my all 10-speeders and designed for medium duty and linehaul trucks. It contains 5-speed main gearbox with reverse gear plus splitter. This one is short inline design, length is only 17 studs with motor and it fits to 8 studs width.

Picture links:

10-speed pic1 (shift pattern)

10-speed pic6 (no bricks)

LDraw files:

lego 10-speed 10.ldr

Brickshelf Gallery:

10speed10

YouTube videos:

12-speed B pic6 (axles only)

This basic 10-speed is only simple and compact design for lego builders without direct inspirer from real truck transmissions. So it’s very lego builder friendly but for reality seekers I recommend to check M.2. 10-speed with splitter version II, which is inpsired by older Scania’s medium duty trarnsmissions.

Although this lego design is very simple and compact upshifting procedure is not the simplest maneuver. In real splitter-type transmissions splitter is pre-selected and button operated. Upshifting procedure goes so that every other shift is easy splitter shift and every other shift more complex compound shift. Skipping gears is easy by ignoring splitter shifts. But lego splitter is pure mechanical so compound shifts are more complex. If you prefer simple operating it’s better to choose 9- or 10-speed transmission with range-change unit, then auxiliary is shifted only once during upshifting procedure. For lego designs check sections D. 9-speed Transmissions or I. 10-speed Transmissions.

L.2. 12-speed version A & B, overall gear ratio 20,00:

Main gearbox + splitter

This basic 12-speed is version IV of my all 12-speeders and it’s an example how to build very simple and compact lego heavy duty transmission that has 6-speed main gearbox and splitter. Essential in this design is to use basic ratios and to put main gearbox and splitter unit parallel. This way you get 12 speeds in gearbox that is as large as my 7-speed gearboxes. Note in this parallel design that three synchro axles on the left are part of main gearbox and they need 6-position H shift patterned shift lever. Splitter’s shift lever is shown in pictures and it uses right synchro axle.

Picture links:

Picture links:

12-speed B pic7 (axles only)

lego 12-speed 4b build.ldr

LDraw files:

lego 12-speed 4.ldr

Brickshelf Gallery:

12speed4

Tutorial2

YouTube videos:

Building example A (modified)

Building example B

Lego gearbox tutorial part II

Version A has brick frame but also version B with studless frame is available. All axles and gear pairs are same in both versions except that splitter’s 4 studs long axle is changed to 5 stud axle. Studless frame is not so colorful as brick frame so download LDraw file or check Building example B if you have difficulties to figure out the construction. Note that shift levers are located parallel and they have own support axles. Put axles only half studs inside middle axle support part called 180 degree angle connector. This way you get both shift lever axles supported at the both ends.

There is also Lego gearbox tutorial part II from this transmission, available with Brickshelf Gallery pictures and YouTube slide show. Unlike versions A and B tutorial version is direct drive.

Also this lego transmission doesn’t have inspirer, mainly because of large overall gear ratio and geometrical gear steps. For reality seekers I recommend to check O.8. 6-speed & 12-speed in O. Medium & Light Truck Transmissions. It’s inspired by older 12-speed ZF S6-66 + GV66 which has 6-speed main gearbox with some progression in gear steps and smaller step in splitter so also overall gear ratio is smaller.

M. 10-speed Transmissions With Splitter, overall gear ratios 10,21:

Main gearbox + splitter
Inspirers:
-Scania GS771 (original lego setup)
-Scania GS770 (alternative lego setup)

10-speed transmission with splitter is very special for me. When I was training for my driving license, I drove Scania, which was equipped with 10-speed GS771 transmission containing 5-speed main gearbox with reverse gear plus splitter unit.

Version I original setup is my old lego design and alternative setup was added later. Version II original and alternative setup are modernized more compact lego designs.

These transmissions have sister transmission D.1. 10-speed with splitter for truck in section D. Gearboxes With 2-speed Motor, page Basic & special designs. Transmission parts are exchangeable so you can replace splitter of these transmissions with 2-speed motor or use these splitters with main gearbox of that 2-speed motor transmission.

M.1. Version I:

Here is version I original and alternative setup of my 10-speed transmissions with splitter (version III of my all 10-speeders). Like Scania’s GS771 transmission original setup has swapped 8th and 9th gear to get halved gear steps in gear pairs 7-8, 8-9 and 9-10. Construction of this lego transmission is a little bit large and complicated, but gear steps are good. Gear steps vary only between 1,35-1,38 and halved gear steps are all 1,17. I didn’t know Scania’s ratio set when I designed this setup but lego version’s ratios are surprisingly close to Scania’s GS771. Check picture Ratio comparison.

Picture links:

10-speed ver3 pic4 (no bricks)

10-speed ver3 pic5 (no bricks)

10-speed ver3 pic6 (no bricks)

Picture links:

10-speed ver3 alter pic5 (no bricks)

10-speed ver3 alter pic1

10-speed ver3 alter pic2

10-speed ver3 alter pic3

10-speed ver3 alter pic4

10-speed ver3 alter pic6 (no bricks)

LDraw files:

lego 10-speed 3.ldr

lego 10-speed 3 alter.ldr

Brickshelf Gallery:

10speed3

YouTube videos:

Building example (original only)

Alternative setup is based on earlier Scania’s GS770 gearbox. Only difference between these Scania’s transmissions is that in GS770 main gearbox’s 4th gear is slower. But this makes transmission’s behavior different because 8th and 9th gear have almost same ratio so GS770 is more like 9-speed transmission. For more info about this feature is in chapter M.3.

These old lego designs are not very optimized, for lego builders I recommend to check next version II original and alternative setup.

M.2. Version II:

Here is version II original and alternative setup of my 10-speed transmissions with splitter (version IX of my all 10-speeders). These setups are re-investigated designs from setups of version I. New designs are more compact but ratio sets are unchanged while they are pretty realistic already in version I. You can check differences from picture Ratio comparison. There are only minor changes between original and alternative setup so they reflect better Scania’s modular designs of GS770 and GS771.

Picture links:

10-speed ver9 pic1 (shift pattern)

10-speed ver9 pic7 (no bricks)

Picture links:

10-speed ver9 alter pic1 (shift pattern)

10-speed ver9 alter pic2

10-speed ver9 alter pic3

10-speed ver9 alter pic4

10-speed ver9 alter pic5

10-speed ver9 alter pic6

10-speed ver9 alter pic7 (no bricks)

Picture links:

LDraw files:

lego 10-speed 9 alter.ldr

Brickshelf Gallery:

10speed9

YouTube videos:

Building example (original & alternative)

Again, original setup (GS771 inspired) has swapped 8th and 9th gear to get halved gear steps in high speed driving (gear pairs 7-8, 8-9 and 9-10). And alternative setup (GS770 inspired) has almost identical ratios in 8th and 9th gear so it’s more like 9-speed transmission. Check idea of this advanced “9-speed” design from next chapter.

These version II setups are lego builder friendly designs. They both contain new 28 teeth gear wheel (ML, medium large in my notations). If you don’t have this new gear wheel you can copy front axles before synchro axles from version I setups and add them to version II setups.

M.3. More about Scania’s splitter-type transmissions:

GS770 and GS771 are older Scania’s 10-speed splitter-type transmissions for light and medium duty trucks. They contain 5-speed main gearbox with reverse gear plus splitter unit which is planetary gear design. Only difference between GS770 and GS771 is different ratio in main gearbox’s 4th gear. Neither has basic geometrical gear steps so here is more about designs and why they are done so.

In GS770 main gearbox’s 4th and 5th gear have almost same gear step as splitter so 8th and 9th gear have almost identical ratios. Shifting sequence in high speeds is ...-6-7-9-10 or ...-6-7-8-10, so you never shift between 8th and 9th gear. So this transmission more like 9-speed design. This design may look weird but but there is a clever idea behind it: At highway speeds you drive in 10th gear which means splitter high. So if you have to slow down or engine rpm drops due to uphill situation you can make easy splitter shift from 10th to 9th gear. This procedure is common to all truck transmissions with splitter. But in slower speed limits when you have to drive in 9th gear you have splitter in low position so there is no easy splitter shift in slow downs and you have to shift with main gearbox. But in Scania’s GS770 you don’t drive with 9th gear in this situation but choose 8th gear with almost same ratio. So you are again in splitter high so you can do easy splitter shift from 8th to 7th gear for small slow downs. This is why 8th and 9th gear have almost same ratio, to give more easy splitter shifts in high speeds.

In GS771 main gearbox’s 4th and 5th gear have smaller step than splitter and this causes 8th and 9th gear to swap in shift pattern. This swap makes halved gear steps in high speed driving meaning shifts 7-8, 8-9 and 9-10. So you still have two high split gears (9th and 10th) in high speeds giving easy splitter shifts for little slow downs. But you have also three halved steps with better performance when needed. Usually you can do basic splitter shift 7-9 and use halved step 9-10 only so typical upshifting sequence with some gear skipping is (1)-3-5-6-7-9-10. All in all these halved gear steps make GS771 more versatile so that’s why it finally replaced GS770.

Together with these splitter-type transmission Scania had 10-speed transmission with range-change unit (like GR871) for medium and heavy duty trucks. Range-type transmissions had larger overall gear ratio giving better move-off and climbing capability. Lego version of GR871 is introduced in chapter I.4. 10-speed version IV.

N. Twin Stick Transmissions:

Inspirer: old Spicer transmissions

Here are my 5x4, 4x4 and 5x3 twin stick transmissions. Also my Lego 4WD vehicle version 8 had twin stick transmission, it’s located on page Vehicles.

N.1. 5x4 version A & B, overall gear ratio 15,43:

5-speed main + 4-speed aux

This one is a good old fashioned twin stick truck transmission. It has 5-speed main gearbox and 4-speed auxiliary gearbox, which is used as a 3-speed splitter. Altogether, the number of gears you’ve got is 5x3+1=16.

Picture links:

Schematics

Twin Stick 5x4 pic1 (no bricks)

Twin Stick 5x4 pic2 bricks

Twin Stick 5x4 pic3 bricks

Main gearbox pic1

Main gearbox pic2

Auxiliary gearbox pic1

Auxiliary gearbox pic2

LDraw files:

twin stick bricks.ldr

main 5-speed basic.ldr

aux 4-speed bricks.ldr

Brickshelf Gallery:

twinstck

YouTube videos:

Twin Stick 5x4 B pic1 (front view)

Links above belong to version A which is the original version with brick frame. Below is version B which has studless frame. Axles, their positions and gear pairs are same in both versions, so ratios and gear steps are also same. Version B is not so colorful as version A so download LDraw file if you can’t figure out structure from next pics.

Picture links:

Twin Stick 5x4 B pic2 (left view)

Twin Stick 5x4 B pic3 (rear view)

Twin Stick 5x4 B pic4 (right view)

Twin Stick 5x4 B pic5 (top view)

Twin Stick 5x4 B pic6 (bottom view)

Twin Stick 5x4 B pic7 (shift patterns)

LDraw files:

twin stick 5x4 b.ldr

Brickshelf Gallery:

TwinstckB

Some notes: Lego version’s gear steps 1,17-1,20 are typical for twin stick transmission but steps 1,26 are slightly too large. And auxiliary has basic shift pattern while in real twin stick transmission gears 3 and 4 are always swapped.

N.2. 4x4, overall gear ratio 13,13:

4-speed main + 4-speed aux
Inspirer: Spicer 8041-A & 8341-G

Here is another type of twin stick transmission. This time main gearbox has only 4 speeds. 4-speed auxiliary is used as 3-speed splitter like in previous 5x4 transmission so the number of gears you’ve got is 4x3+1=13. Available is both inline and parallel setups so depending on lego truck’s design builders can choose between long and narrow setup and short and wide setup, ratio sets are identical.

Picture links:

Twin stick 4x4 inline pic1

Twin stick 4x4 inline pic2

Twin stick 4x4 inline pic3

Twin stick 4x4 inline pic4

Twin stick 4x4 inline pic5

Twin stick 4x4 inline pic6 (no bricks)

Picture links:

Twin stick 4x4 parallel pic1

Twin stick 4x4 parallel pic2

Twin stick 4x4 parallel pic3

Twin stick 4x4 parallel pic4

Twin stick 4x4 parallel pic5

Twin stick 4x4 parallel pic6 (no bricks)

Picture links:

Ratios inline

Ratios parallel

lego twin stick 4x4 inline.ldr

LDraw files:

lego twin stick 4x4 parallel.ldr

Brickshelf Gallery:

TwinStick2Remake

YouTube videos:

These twin stick 4x4 setups are remakes with more realistic ratio set and shift patterns including swapped 3rd and 4th gear in auxiliary. In these remakes inspirer is real Spicer’s main gearbox and auxiliary combination, you can check differences between lego version and real transmission from picture Ratio comparison.

Original lego setups had some reality issues while some gear steps and further overall gear ratio were too large for old twin stick transmission. Twin stick transmissions need small gear steps while in old trucks usable engine rpm range was very narrow. And lego auxiliary’s shift pattern didn’t have that gear swap. If you want to check old version it’s still available on page Junkyard.

N.3. 5x3, overall gear ratio 12,60:

5-speed main + 3-speed aux

This twin stick 5x3 transmission is easier to use than previous versions with 4-speed auxiliary. Now auxiliary’s all 3 gears are used to split main gearbox’s gears so number of gears is 15. Compared to 5x4 this 5x3 has about same gear steps but one gear less means smaller overall gear ratio. Also this transmission doesn’t have same versatility given by 5x4’s extra gears and overlapping ratios.

Picture links:

LDraw files:

Brickshelf Gallery:

Twinstick3

YouTube videos:

This lego version has swapped gears in auxiliary’s shift pattern like real twin stick transmissions. Gear steps 1,17-1,20 are realistic but steps 1,29 are too large. For alternative ratio set you can use auxiliary of next 5x4 version II without its 1st gear.

N.4. 5x4 version II, overall gear ratio 18,00:

5-speed main + 4-speed aux
Inspirer: Spicer 8052 & 8341-F

This 5x4 version II is updated design of earlier 5x4 twin stick transmission. Main gearbox is pretty much the same but auxiliary is more realistic: it has swapped 3rd and 4th gear in shift pattern and it gives better ratios and gear steps. 5-speed main gearbox covers whole speed range so it has large gear steps. When needed main gears can be splitted with auxiliary’s gears 2-4. Auxiliary’s 1st gear is used with 1st main gear and it’s for low speeds or move offs in difficult conditions. So number of gears is 5x3+1=16 but pro user can take advantage of extra gears by using auxiliary’s 1st with main gears 2-5.

Picture links:

Twin stick 5x4 ver2 pic1

Twin stick 5x4 ver2 pic2

Twin stick 5x4 ver2 pic3

Twin stick 5x4 ver2 pic4

Twin stick 5x4 ver2 pic5

lego 5x4 twin stick ver2.ldr

LDraw files:

Brickshelf Gallery:

Twinstick4

YouTube videos:

This time inspirer is specified combination of Spicer’s main gearboxes and auxiliaries. Lego version follows ratios and gear steps quite closely with two exceptions: gear steps 1-2 and 3-4 (1,80) in main gearbox are too large because of simple lego design. These exceptions make lego version’s overall gear ratio much larger than Spicer’s one. You can check differences from picture Ratio comparison.

This transmission has underdrive sister design in my Lego 4WD vehicle version 8, it can be found on page Vehicles. Lego 4WD vehicle is rear engine design but you can check the idea of underdrive auxiliary if you need higher total ratios for high speed lego motor. Gear steps and overall gear ratio are identical in these lego sisters.

N.5. More about twin stick transmissions:

Twin Stick Transmission means that driver has two shift levers without help of preselector gearboxes (splitter or range-change unit). First driver shifts only auxiliary gearbox in upshifting procedure. When auxiliary gearbox reaches top gear, it’s time to make a compound shift. This means that main gearbox must be shifted up one gear, but auxiliary gearbox must be shifted down from 4th to 2nd gear (in 4-speed auxiliary) before the whole transmission is in desired gear. And then, only auxiliary gearbox is needed to make next upshifts. When auxiliary gearbox has reached top gear again, it’s time to repeat the compound shift. This is repeated until you reach top gear in both gearboxes.

Notable thing is that two top gears are always swapped in auxiliary’s shift pattern. I haven’t copied this feature to all my lego twin stick transmissions. This swap comes from overdrive gearbox. In direct drive gearbox gear pairs are located so that frontest is direct top gear (input and output shafts connected together), then in decreasing order other gears until rearest is 1st gear and then possible reverse gear. For example in direct drive 5+R-speed main gearbox it goes like this in downshifting procedure: In shift pattern’s right gate shift lever movement to rear moves shifting linkage forward to top gear and lever’s move to forward gives linkage movement to rearward to first underdrive gear, and this gives gear pair 5-4. Then in middle gate same moves give gear pair 3-2 and in left gate gear pair 1-R. So there is nice harmony in shift pattern and inside gearbox from front to rear. But in overdrive gearbox direct gear is still frontest and after it is gear pair of overdrive top gear and this ruins the harmony: In overdrive 4-speed auxiliary right gate’s shift lever movement to rear connects direct 3rd gear from front and lever’s move to front gives overdrive 4th gear from rear. So there is swapped gear pair 3-4 (not 4-3) in right gate while left gate gives normal gear pair 2-1. If you want to normal H shift pattern to overdrive gearbox right gate needs extra reversing lever in shifting linkage to eliminate gear swap. Nowadays they always eliminate this gear swap but in older transmissions like twin stick auxiliaries this swap is reality.

There are two reasons for that extra 1st gear in 4-speed auxiliary: Firstly you get slower starting gear and a little bit larger overall gear ratio. Secondly you can have more downshifts without main gearbox shifting for example from 3-2 (main-aux) to 3-1 instead of 2-4. The latter compound shift is not normally used in uphill situations but direct downshift to 2-2 because driving speed drops too much in compound shift before you are back in gear.

There can be alternative ratio setup in auxiliary so that 1st and 2nd gear has very large gear step. This gives two slow gears (1-1 and 2-1) before gear 1-2. It also means that auxiliary’s 1st gear can’t be used in downshiftings. So this setup is usually together with smaller gear step between main gearbox’s 4th and 5th gear. Then you shift after gear 4-4 direct to 5-3 without 5-2 (or direct to 5-4 without 5-2 and 5-3) so these overlapping gears give versatility to shifting in high speeds.

Twin stick transmission with 3-speed auxiliary is simpler to use because it doesn’t have extra gears: in compound shift main gearbox is shifted up one gear but auxiliary is shifted down from 3rd to 1st gear. But remember that also 3-speed auxiliary is overdrive design so it has gear swap between two top gears.

Too complicated? Check out next YouTube clips. Maybe it helps... or not. I needed several repeats before I understood what really happened in these clips. :-)

Here you can check some real twin stick 5x3 driving: http://youtu.be/2mf6AUbjT-s. Just wait until driver makes two handed compound shifting, I’ll bet you want to see that.
Here is twin stick 5x4 example: http://youtu.be/ol7StdtHEMc.
Here is same 5x4 truck in another upshifting: https://youtu.be/r6UsiSoddWQ. Although you can’t see driver it is easy to follow upshifting: auxiliary shifts are fast, compound shifts aren’t.

[Back to top]

[Links & Notes]

[A.-B.]

[C.-F.]

[G.-J.]

[K.-N.]

[O.]

[P.]

[Q.]

[R.]

[S.]

[T.]

[U.]

O. Medium & Light Truck Transmissions:

Mainly progressive gear steps

Like personal car transmissions most of these medium and light truck transmissions have only main gearbox without splitter or range-change unit. So you can use progressive gear steps, which means the higher gear the smaller gear step between gears. Although 12-speed transmission has splitter unit and 8-speed transmissions have range-change unit also those main gearboxes have some progression in gear steps. Major difference between personal car and light truck transmissions is that light trucks have larger gear steps and overall gear ratio. In real world light truck transmissions are also stronger and heavier while they have to handle more torque.

Note that here medium truck means mid range lorry or commercial truck, not pickup truck. And light truck means pickup, van or small lorry.

O.1. 5-speed version V, overall gear ratio 6,00:

Inspirer: ZF S5-42

This transmission is 1st light truck transmission but 5th 5-speed transmission. First four 5-speed gearboxes are later shown personal car gearboxes.

Picture links:

LDraw files:

Brickshelf Gallery:

Prog55

YouTube videos:

This transmission is also big brother of later shown 4-speed version I personal car transmission. Only difference is added slow gear, ratios of other gears are straight from 4-speed gearbox. New 1st gear and large gear steps of 4-speed gearbox make this transmission perfect to light truck use.

You may notice that this gearbox has actually 6 gears. Problem is that gear step between 1st gear and slow extra gear doesn’t suit to this gearbox’s gear step progression. That why slow extra gear is abandoned. If you build this gearbox you have to make shift pattern that doesn’t allow to switch to that extra gear (check Building example).

O.2. 5-speed version VI, overall gear ratio 5,71:

Inspirer: ZF S5-42

This 5-speed light truck transmission is based on later shown 4-speed version II personal car transmission. New feature is added slow gear, other gears’ ratios are taken from 4-speed gearbox. This version much simpler than previous light truck transmission but price is that gear step progression is not so good.

Picture links:

LDraw files:

Brickshelf Gallery:

Prog56

YouTube videos:

While input axle is supported by two technic brick 1x2 with 2 holes you may have difficulties to attach studded lego motor to the input axle. If you need hints to solve this problem check 4-speed version II in personal car transmissions.

O.3. 6-speed version II, overall gear ratio 8,00:

Inspirer: Eaton Fuller FS-6406B

Here is 6-speed version of medium & light truck transmissions. Gear steps are only partly progressive and progression is not very strong. This means that largest gear step 1-2 is only 1,67 so this transmission works also with larger low speed diesel engine in which performance speed range (engine speeds from maximum torque to maximum power) is more narrow than in light trucks with smaller engines.

Picture links:

LDraw files:

lego 6 prog 2 remake.ldr

Brickshelf Gallery:

Prog62Remake

YouTube videos:

This design is remake with more compact and simpler design but price is that ratio set is not so optimized. But ratio set is still quite realistic, check gear step comparison in picture Ratio comparison (lego version is overdrive but Fuller direct drive). Original version has better ratio set but otherwise design is not very good. But it’s still available on page Junkyard if you want to check it.

So, here is quite simple and usable universal lego 6-speed transmission with realistic ratio set for light truck, lighter medium duty truck, heavier van and pickup truck.

O.4. 6-speed version IV, overall gear ratio 8,57:

Inspirer: ZF S6-66

Here is another 6-speed light truck transmission. Structure before synchro axles is simpler than in previous 6-speed version but after synchro axles structure is more complicated. All in all this transmission is quite small for 6 speeder that has progressive gear steps.

Picture links:

LDraw files:

lego 6 prog 4 remake.ldr

Brickshelf Gallery:

Prog64Remake

YouTube videos:

6-speed B pic6 (shift pattern)

This lego design is remake. Original design has XS(8)-M(24) gear pair after synchro parts. So there are significant overdrive situations in some gear wheels in some gears which can lead to bad efficiency. So original design is moved to page Junkyard if you want to check it.

While input axle is supported by two technic brick 1x2 with 2 holes you may have difficulties to attach studded lego motor to the input axle. If you need hints to solve this problem check 4-speed version II in personal car transmissions.

O.5. 6-speed version VI A & B, overall gear ratio 7,50:

Inspirer: ZF Ecolite

6-speed Transmission Version VI Alternative Setup

Here is very simple version of 6-speed transmission that has progressive gear steps. But problem was that its overall gear ratio is too high for personal cars and slightly too small for light trucks. With some web search I found that lighter version of current ZF Ecolite has overall gear ratio 7,62 so this lego version VI became as light truck transmission that also suits for wide ratio personal cars that are usually diesel powered in real world. All in all lego design has good progressive gear steps and there are no significant overdrive situations in any gear wheel in any gear so gearbox’s efficiency should be good.

Picture links:

Picture links:

Picture links:

LDraw files:

lego 6 prog 6.ldr

lego 6 prog 6 alter.ldr

lego 6 prog 6b.ldr

Brickshelf Gallery:

Prog66

YouTube videos:

Building example alter & version B

Available is two brick frame setups plus studless version B. In brick frames old school original setup uses 14 teeth thin bevel gears and modernized alternative setup has 20 teeth clutch gear. These setups have different design in 2nd and 5th gear but only ratio change is in 2nd gear. Gear wheel changes also makes alternative setup slightly more narrow. Version B with studless frame uses same gear wheels and ratios as alternative brick frame setup.

So, if you are looking for 6-speed lego transmission for light truck, van, pickup or wide ratio personal car I recommend to build one of these choices. And if you abandon 1st gear in lego version you get 5-speed personal car transmission with typical overall gear ratio 4,29 (original) or 4,00 (alternative & version B). So this lego version is quite versatile.

O.6. 7-speed, 1 reverse gear, overall gear ratio 11,67:

Inspirer: Eaton Fuller 7-speed B ratio (like T-14607B in Eaton Transmission Specifications Catalog)

Wide ratio version of 7-speed transmission with progressive gear steps can be used in buses & coaches (city buses with automatic transmissions excluded) and light & medium duty trucks. It can offer quite good performance in high speeds (top gear step 6-7 only 1,25 in lego version) with mid-range move off and climbing capability (overall gear ratio now 11,67) in same single gearbox without auxiliaries. But engine’s torque peak must be wide enough that it can handle large gear step 1-2 (now 1,80), so 7-speeder doesn’t suit to largest truck engines.

Picture links:

LDraw files:

lego 7 prog remake.ldr

Brickshelf Gallery:

Prog7Remake

YouTube videos:

This lego version is remake with several improvements: design is simpler and two studs shorter, and reverse gear is added. Design is also modernized while it uses new 28 teeth gear (ML) and 20 teeth clutch gear (Mu’) instead of old 14 teeth thin bevel gears. Original design is still available on page Junkyard if you want to check it.

Modernization causes that lego version’s reverse gear is slower than in real 7-speed transmissions. But if you have old 14 teeth thin bevel gears you can do simple reality upgrade: just change reverse gear’s Su(12)-Su(12)-Su(12)-Mu(20) gear train to Th(14)-Su(12)-Su(12)-Mu(20), it changes reverse ratio to -10,00.

In my opinion 7+R-speed is largest manual transmission you can handle with single shift lever and H shift pattern. 6 forward gears keep things simple when shift lever centers itself to 3-4 line, movement to right gives 5-6 line and movement to left gives 1-2 line. And if reverse gear is behind lock or extra spring load 6+R-speed can be shifted without risk of wrong gear. In 7+R-speed lines R-1 and 6-7 need some extra spring resistance or other methods that you don’t accidentally shift to those gears while shifting to gears 2-5. This is when neutral is between lines 2-3 and 4-5. If neutral is in line 4-5 only line R-1 needs extra spring resistance.

O.7. 7-speed version IV, 1 reverse gear, overall gear ratio 13,13 REMAKE:

Inspirer: Eaton Fuller 7-speed B ratio (like T-14607B in Eaton Transmission Specifications Catalog)

This 7-speed transmission version IV is wide ratio design with strongly progressive gear steps. Like previous 7-speed it can be used in buses & coaches (city buses with automatic transmissions excluded) and in light & medium duty trucks. So it combines good performance in high speeds (top gear step 6-7 only 1,25 in lego version) and good move off and climbing capability (overall gear ratio now 13,13) for light and medium duties. But price is that engine needs wide torque peak to handle large gear steps in lower gears (step 1-2 now 1,84), so strong progression is not usable with largest truck engines.

Picture links:

7-speed pic1 (shift pattern)

7-speed pic6 (no bricks)

LDraw files:

lego 7 prog 4 remake.ldr

Brickshelf Gallery:

Prog74Remake

YouTube videos:

Ratios 6-speed and 12-speed

This lego version is remake with two improvements: design is smaller and reverse gear is added. Original design is still available on page Junkyard if you want to check it.

This 7-speed mixes old and new technic while it has old 14 teeth thin bevel gears (Th) and new 20 teeth clutch gears (Mu’). This mix gives some reality advantages like slightly faster reverse gear than 1st gear. If you don’t have old 14 teeth gears previous 7-speed version I is modern version for you.

O.8. 6-speed & 12-speed, overall gear ratios 8,33 & 10,71:

Inspirer: ZF S6-66 & ZF S6-66 + GV66

These gearboxes are inspired by ZF’s transmission S6-66 and its additional splitter unit GV66. Splitter means that main gearbox’s front mounted constant gear pair is replaced with 2 constant gear pairs. New constant gear ratios mean that main gearbox’s gear step 5-6 becomes larger to be suitable for splitting, but other main gearbox’s gear steps stay unchanged. Of course all ratios are different except direct gear.

While S6-66 is only main gearbox it has progressive gear steps. When splitter GV66 is added gear steps in higher gears become geometrical. Also splitter’s gear steps (1-2, 3-4, 5-6 etc.) are geometrical (constant value). But in compound shifts (2-3, 4-5, 6-7 etc.) and when only main gearbox is used gear steps are progressive except 2 highest gear steps. So gearbox S6-66 + GV66 has partly progressive gear steps.

Picture links:

6-speed pic5 (no bricks)

Picture links:

12-speed pic6 (no bricks)

LDraw files:

lego 6 prog 5.ldr

lego 12-speed 3.ldr

Brickshelf Gallery:

6and12speed

YouTube videos:

Dual building example (modified)

Redesigned lego versions (6-speed version V & 12-speed version III) follow quite closely ZF’s modular design. 6-speed transmission needs only two modifications to get 12-speed version: ratio of top gear is changed from 0,75 to 0,70 (gear step changed from 1,33 to 1,43) and splitter is added. This means some minor changes in gear wheels and bricks but 6-speeder and main gearbox of 12-speeder are very close to each other. If you want compare these lego designs check YouTube clip in which transmissions are built simultaneously.

O.9. 8-speed, 2 reverse gears, overall gear ratio 9,80:

Inspirer: Scania GR875 & Volvo R52

This 8-speed transmission has 4-speed main gearbox with a reverse gear and range-change unit. Although there is range-change unit main gearbox has some progression in gear steps. This feature is taken from those Scania’s and Volvo’s gearboxes.

Picture links:

LDraw files:

Brickshelf Gallery:

8speed

YouTube videos:

8-speed alter pic5 (no bricks)

Progressive gear steps and range-change unit is a little bit problematic combination while gear step 3-4 is significantly smaller than next range change 4-5 and gear step 5-6. If you have to use all the gears (for example heavy loaded) low range is just continuous upshifting until you come to range shift. But in high range progression is good thing while you can take advantage of decreasing gear steps in high speeds. And if you can skip gears upshifting sequence 2-4-5-6-7-8 gives fully progressive gear steps. More info about progressive gear steps and why they are not often used with auxiliary gearboxes is in page Gearbox theories.

Note that lego version has 2 reverse gears but high range reverse is not advertised in Scania’s and Volvo’s gearboxes. Reason for this is that high range reverse is too fast for move off so you need to start with low range and make large gear step range change to get high reverse. And for many situations high reverse is just too fast while you need to look both mirrors to see where you are going.

O.10. 8-speed version II, 2 reverse gears, overall gear ratio 10,88:

Inspirer: Volvo R62

Here is another 8-speed transmission that has 4-speed main gearbox and range-change unit. Also this version II has some progression in gear steps but not so much as version I. Structure in this version II is more compact and simpler than in version I while length is reduced from 19 studs to 15 studs and axles and gear wheels are packed in 2 layers instead of 3. If you have low speed motor and 8 gears are enough here is your choice.

Picture links:

8-speed pic5 (no bricks)

8-speed pic6 (no bricks)

Picture links:

8-speed alter pic6 (no bricks)

LDraw files:

lego 8-speed 2.ldr

lego 8-speed 2 alter.ldr

Brickshelf Gallery:

8speed2

YouTube videos:

Available is also alternative setup in which main gearbox and range-change unit are located parallel. So this setup is shorter but wider. For main gearbox’s shift lever use 8 studs long axle with longitudinal bricks at the both ends. Put bush to the right side of the left brick to prevent axle’s movement to the left. For range shift lever use axle pin and 3rd longitudinal brick on the right side. While range lever is between bricks it’s well supported. Range lever also prevents main lever’s axle to slide to the right.

While input axle is supported by two technic brick 1x2 with 2 holes you may have difficulties to attach studded lego motor to the input axle. If you need hints to solve this problem check 4-speed version II in personal car transmissions.

One interesting fact is that gear steps are very close to each other in lego version and Volvo R62 transmission. But ratios are all different while lego version is overdrive and Volvo’s transmission direct drive. Check picture called Ratio comparison. Note in Volvo’s transmission that 2 decimal accuracy in ratios causes calculation error between gear steps 2-3 and 6-7, they should have same value.

One notable thing is that gear step 7-8 (also 3-4 due to range-change unit) is smaller than the others. In real trucks engine rpm is often matched to be in economic zone when you drive in top gear at highest allowed speed limit. In Europe this speed limit is usually 80 km/h. If gear step 7-8 is for example as high as 1,40 speed in 7th gear is only about 57 km/h when you drive in same engine rpm as in top gear at speed 80 km/h. So speed limit 70 km/h means trouble because in top gear engine rpm is too low (not enough power for uphill situations) but too high in 7th gear (increases fuel consumption). Other problem is in acceleration to 80 km/h while you need to rev engine out of economic zone in 7th gear before upshift to top gear if you want to get faster acceleration. Early upshift to top gear means slower acceleration because in lower engine rpm you have less power and in high speeds you need most power. These are the reasons why they often make gear step 7-8 smaller in 8- or 9-speed transmissions.

O.11. 8-speed version III, 2 reverse gears, overall gear ratio 9,12:

Inspirer: Scania GR875

Here is one more 8-speed transmission that has 4-speed main gearbox and range-change unit. This time main gearbox has strong progression in gear steps to be used with auxiliary gearbox. Ratios of lego version are copied from Scania’s 8-speed transmission and you can check picture Ratio comparison to see how close ratios are to each other. Progression in main gearbox means that all gear steps in low range are too small. But from range change and in high range you can take advantage of decreasing gear steps. And if you can skip 1st and 3rd gear you get six gears with good progressive gear steps.

Picture links:

Picture links:

LDraw files:

lego 8-speed 3 alter.ldr

Brickshelf Gallery:

8speed3

YouTube videos:

There are two setups available in lego version. In original setup main gearbox and range-change unit are located parallel so transmission is short but wide. For shift lever axles you need 3rd longitudinal brick to be placed between gearboxes. When you put both axles only half studs inside this middle brick shift levers are well supported. In alternative setup range-change unit is in front of main gearbox so this setup is longer but more narrow. There are some gear pair changes in alternative setup but they don’t affect to ratios and gear steps.

Progressive gear steps in main gearbox make lego structure a little bit complicated but it was difficult to get gear step 1,46 with lego gears. Gear step 1,43 would have been much easier to get but then overall gear ratio would have become too small and it is already small in this transmission.

One notable thing in Scania’s transmission is that reverse gear is significantly slower than 1st gear while in lego transmission they have same ratio. If you want slower reverse gears for lego version there is a simple conversion you can do in alternative setup: replace gears XS(8)-XS(8)-XS(8) with Su(12)-Su(12)-Th(14). Next pictures and YouTube video show you more info.

Picture links:	Ratios alter2	8-speed alter2 pic1	8-speed alter2 pic2

YouTube videos:	Building example alter 2 (modified)

You can also convert original parallel setup but you need to move gears wheels of reverse from front to rear.

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P. Personal Car & Sport Car Transmissions:

Progressive gear steps
Inspirers: Various personal cars & sport cars

Many truck transmissions shown in this page are based on geometrical gear steps. It’s the usual way to build a transmission that has splitter or range-change unit, or both. But the following transmissions are single 3-7-speed gearboxes which don’t have problems made by auxiliary gearboxes. Progressive gear steps means the higher gear the smaller gear step between gears.

Note that next 5-speed gearboxes look like they have 6 gears. The problem in those gearboxes is that gear step between 1st gear and slow extra gear is wrong, so it will ruin the gear step progression. That’s why they have only 5 gears. When you build them you have to make 5-speed shift pattern which doesn’t allow to switch to the extra gear. Another notable thing is that in H shift pattern 1st gear is in left rear (truck configuration), not in left front (personal car configuration). It is easier to get progressive gear steps in truck configuration. But there is also personal car configuration available, check 5-speed version II alternative setup II.

P.1. 5-speed version I A & B, overall gear ratio 5,00:

This first version is also the simplest. Version I A is the original version with brick frame and version I B has studless frame.

In this gearbox gear step 4-5 is good but gear step 3-4 is too large, gear steps of lower gears are also good. This one exception means also that gear step progression isn’t very smooth. Overall gear ratio is too large for the 5-speed personal car (normally 4,00-4,50) but too small for the 5-speed light truck.

Picture links:	Ratios	5-speed pic1	5-speed pic2	5-speed pic3

Picture links:	5-speed IB pic1 (front view)	5-speed IB pic2 (rear view)	5-speed IB pic3 (top view)	5-speed IB pic4 (bottom view)	5-speed IB pic5 (shift pattern)

LDraw files:	lego 5 prog.ldr	lego 5 prog 1b.ldr

Brickshelf Gallery:	Prog5	Prog51B

YouTube videos:	Building example (modified)

Version I B uses only studless parts. All the axles, gear wheels and gear pairs are exactly same as in original version, so ratios and gear steps are also same. This time I didn’t use colorful parts so download LDraw file if you can’t figure out the structure from pictures.

P.2. 5-speed version II, overall gear ratio 3,57 UPDATED:

This version II has small overall gear ratio for typical 5-speed personal car so this is called close ratio design. Gear step progression is quite light but very smooth.

Picture links:	Ratios alter	5-speed alter pic1	5-speed alter pic2	5-speed alter pic3

Picture links:	Ratios alter 2	5-speed alter 2 pic1	5-speed alter 2 pic2	5-speed alter 2 pic3	5-speed alter 2 pic4

LDraw files:	lego 5 prog 2 alter.ldr	lego 5 prog 2 alter2.ldr

Brickshelf Gallery:	Prog52

YouTube videos:	Building example alter (modified)	Building example alter 2 (modified)

Available are alternative setups I & II (alter & alter2) with identical ratio set. Original design has more complex design while it has three axles before and above synchro axles. But it’s still available on page Junkyard or in Brickshelf Gallery if you want to check it.

Alternative setup I has truck H shift pattern while 1st gear is in left rear. Note that ratio of that empty gear position is not usable while it’s actually faster than 1st gear. Alternative setup II is special design while it has standard personal car H shift pattern, first time in my 5-speed gearboxes. So if close ratio version for personal car is suitable here is quite good lego design to build. In theory alternative setup II could be equipped with reverse gear by adding gears S’(16C)-Mu(20) and XS(8)-XS(8)-M(24) from empty gear position to output axle. But that would lead very bad efficiency while in forward gears reverse gear’s clutch gear would spin very fast to opposite direction than its axle.

P.3. 5-speed version III, overall gear ratio 4,17:

This 5-speed version III is based on previous version II. Gears 3-5 are same as earlier, but 1st and 2nd are slower. This modification gives you perfect overall gear ratio. Despite the modification gear step progression is still good.

Picture links:	Ratios	5-speed pic1	5-speed pic2	5-speed pic3	5-speed pic4 (no bricks)

Picture links:	Ratios alter	5-speed alter pic1	5-speed alter pic2	5-speed alter pic3	5-speed alter pic4

LDraw files:	lego 5 prog 3.ldr	lego 5 prog 3 alter.ldr

Brickshelf Gallery:	Prog53	Tutorial

YouTube videos:	Building example alter (modified)	Lego gearbox tutorial

Later I found out that this gearbox could be simpler so here is also alternative setup. With gear rearrangement you can get rid of the axles before and above synchro axles. Modification doesn’t affect to ratios or gear steps so this is just update not new gearbox. Note that this alternative setup doesn’t have possibility to slow extra gear because extra gear has same ratio as 1st gear. If you want to build 5-speed gearbox I recommend to build this 5-speed version III alternative setup, it’s simple construction and still has good progressive gear steps.

There is also Lego gearbox tutorial from this 5-speed version III alternative setup with little modifications. Available with Brickshelf Gallery pictures and YouTube slide show.

P.4. 5-speed version IV, overall gear ratio 4,00:

The reason for another 5-speed transmission is that this gearbox’s gear steps and gear step progression are so close to the theory of progressive gear steps. Not even all real personal car transmissions are so close to theory, because number of teeth in gear wheels are intergers so it’s not always easy to get the desired ratio. Also you change ratios a little when matching engine and gearbox. (More info at Gearbox theories.) To make smooth gear steps possible there is a rare gear pair in this transmission: two 14 teeth thin bevel gears with 16 teeth gear. 14 teeth gears are not designed for spur gear solutions, so I’m not sure how good they work with 16 teeth gear under torque. Unlike many other gearboxes shown in this page, this gearbox has overdrive top gear.

Picture links:

5-speed pic4 (no bricks)

5-speed pic5 (no bricks)

5-speed pic6 (no bricks)

LDraw files:

lego 5 prog 4.ldr

Brickshelf Gallery:

Prog54

YouTube videos:

4-speed B pic1 (axles only)

Next table compares this lego gearbox to theoretical values when top gear’s ratio is 0,833, basic gear step 1,200 and progression factor 1,115.

	LEGO		THEORY

Gear	Ratio	Gear step	Ratio	Gear step

1st	3,333	1-2: 1,667	3,320	1-2: 1,663

2nd	2,000	2-3: 1,500	1,996	2-3: 1,492

3rd	1,333	3-4: 1,333	1,338	3-4: 1,338

4th	1,000	4-5: 1,200	1,000	4-5: 1,200

5th	0,833	Overall: 4,000	0,833	Overall: 3,985

P.5. 5-speed version VII, overall gear ratio 3,40:

Immer wieder Fünfganggetriebe... Well, this version VII (versions V & VI are light truck transmissions) is simple construction like 5-speed version I. It’s also close ratio gearbox for sport cars like 5-speed version II. This time gear steps 3-4 and 4-5 are very small but gear steps 1-2 and 2-3 are larger (more progression) to avoid too small overall gear ratio.

Picture links:	Ratios	5-speed pic1	5-speed pic2	5-speed pic3	5-speed pic4

LDraw files:	lego 5 prog 7.ldr

Brickshelf Gallery:	Prog57

YouTube videos:	Building example (modified)

This gearbox contains lots of thin 14 teeth bevel gears so be careful to put them right if you build this gearbox. Also note that there is no slow extra gear available in this gearbox while it has same ratio as 1st gear.

P.6. 4-speed, overall gear ratio 3,33:

Inspirer: Ford Escort

This 4-speed gearbox has smooth gear step progression (it’s easier to build when only 4 gears). Overall gear ratio is quite small but it’s not possible to have large overall gear ratio and small gear steps in the same 4-speed gearbox.

Picture links:	Ratios	4-speed alter pic1	4-speed alter pic2	4-speed alter pic3	4-speed alter pic4

LDraw files:	lego 4 prog alter.ldr

Brickshelf Gallery:	Prog4

Here is available only alternative setup which is as narrow as my other 4-speed gearboxes. Original setup is not very optimized while it’s as wide as 5- or 6-speed lego gearboxes. So it’s only recommendable when you add reverse gear and need to use five position H shift pattern. But you can still check original setup from page Junkyard or link Brickshelf Gallery.

P.7. 4-speed version II A & B, overall gear ratio 3,17:

This 4-speed version II is an update from the previous 4-speed alternative setup, which is already narrow construction. In this version ratios before synchro parts are simplified to get rid of first two axles above synchro part axles. So structure is also flatter which gives very compact and quite simple design. Price is that gear step progression is not so smooth than in 4-speed version I but it’s still pretty good.

Available is also version B with studless frame with one gear wheel change: idler of 4th gear is changed from 8 to 16 teeth gear. You may have difficulties to figure out the construction from pictures so I recommend to download LDraw file or check YouTube slideshow.

Picture links:

Picture links:

4-speed B pic2 (axles only)

LDraw files:

Brickshelf Gallery:

Prog42

YouTube videos:

Building example A (modified)

Building example B

You can use also other bottom layer axle as output so there is available alternative brick frame setup. This modification simplifies power flow in 1st and 3rd gear but complicates it in 2nd and 4th gear. So this setup highlights good efficiency in direct 3rd gear but price is poorer efficiency in top gear.

Picture links:	Ratios alter	4-speed alter pic1	4-speed alter pic2	4-speed alter pic3	4-speed alter pic4

LDraw files:	lego 4 prog 2 alter.ldr

Brickshelf Gallery:	Prog42

While in version A:s input axle is supported by two technic brick 1x2 with 2 holes you may have difficulties to attach studded lego motor to the input axle. One method is to use couple of plate 1x2 with 1 centre stud to get motor half stud sideways. Other solution is to use gear pair between motor and gearbox: For example two 12 teeth gears (or 8-16 gear pair) moves motor 1,5 stud sideways from the input axle. Or you can put vertical two 16 teeth gears (also 12-20 or 8-24 gear pairs) with half studs horizontal movement.

If 4 gears are enough I recommend to build one of these versions so you get compact gearbox. But if you need slower 1st gear check next 4-speed version III which is wide ratio design.

P.8. 4-speed version III, overall gear ratio 4,29:

4-speed Version III & Transfer Case Version V

Here is another simple and compact 4-speed transmission. This one is wide ratio version inspired by old diesel powered personal cars. So if setups of previous 4-speed version II give too fast 1st gear it’s worth to try this version III.

Picture links:	Ratios	4-speed pic1	4-speed pic2	4-speed pic3	4-speed pic4

LDraw files:	lego 4 prog 3.ldr

Brickshelf Gallery:	Prog43

YouTube videos:	Building example (modified)

4-speed version III & transfer case version V

Ratio set of this 4-speed version III is typical for example in older off-road vehicles like Mitsubishi Pajero or Ford Bronco II. So it’s logical to offer also lego version with additional transfer case.

Picture links:

Picture links:

LDraw files:

lego 4 prog 3 tc5.ldr

Brickshelf Gallery:

Prog43

YouTube videos:

This modified transfer case version V is 2-speed part-time 4x4 design with modes H2 (high RWD), H4 (high 4WD) and L4 (low 4WD). High ratio of transfer case is 1,00 and low ratio 2,25. While there is no centre differential in this transfer case you are supposed to use rear wheel drive in good conditions. When conditions get worse you can choose from fast and slow four wheel drive.

P.9. 4-speed version IV, overall gear ratios 2,78, 2,50 & 2,86:

Inspirer: Borg Warner Super T-10 (Richmond Gear, present manufacturer)
Lego original: X ratio
Alternative I: S ratio
Alternative II: CC ratio

These three setups of lego 4-speed version IV are inspired by old 4-speed Borg Warner Super T-10 transmission and its different ratio sets. This transmission is commonly used in old American muscle cars. Ratio sets have changed during years and depended on car maker but here is three ratio sets that are easy to build with legos, check picture Ratio comparison. Borg Warner’s X ratio and S ratio has smaller top gear step 3-4 and stronger progression than CC ratio which is closer to geometrical gear steps. And X ratio has slightly slower 1st gear and larger overall gear ratio than S ratio, otherwise their ratios are identical. All these three are close ratio designs for sport cars.

Picture links:	4-speed pic1	4-speed pic2	4-speed pic3	4-speed pic4

Picture links:	4-speed alter pic1	4-speed alter pic2	4-speed alter pic3	4-speed alter pic4

Picture links:	4-speed alter2 pic1	4-speed alter2 pic2	4-speed alter2 pic3	4-speed alter2 pic4

Picture links:	Ratios	Ratio comparison

LDraw files:	lego 4 prog 4.ldr	lego 4 prog 4 alter.ldr	lego 4 prog 4 alter2.ldr

Brickshelf Gallery:	Prog44

YouTube videos:	Building example (modified)

Lego original design (follows X ratio) is quite simple and narrow design in which 1st gear’s gear pair helps to get 3rd gear’s ratio. Alternative setup (S ratio) is simple but wider, but also closer to theoretical progressive gear steps. Alternative setup II (alter2, CC ratio) is simple and narrow lego setup but it differs from its inspirer so that lego design is overdrive while all these Borg Warner’s gearboxes are direct drive. Also this setup has good progressive gear steps but progression is very light.

There is also 2-speed motor version for original setup (X ratio), check chapter D.3. 4-speed version B for muscle car on page Basic & special designs.

If you need close ratio gearbox for old American muscle car or other older sport car here is three usable setups where to choose from.

P.10. 4-speed version V, overall gear ratios 2,61, 2,90 & 3,42:

Inspirer: Borg Warner Super T-10 (Richmond Gear, present manufacturer)
Lego original: W ratio
Alternative I: Y ratio
Alternative II: Z ratio

These three setups of lego 4-speed version V are another set inspired by 4-speed Borg Warner Super T-10, old American muscle car transmission with different ratio sets. Common for these three ratio sets is that they don’t have pure progressive gear steps. Borg Warner’s W ratio and Y ratio are otherwise very close to each other but Y ratio has larger gear step 1-2 and so also larger overall gear ratio. Z ratio has almost geometrical gear steps, significantly larger top step 3-4 and larger overall gear ratio than other ratio sets. So you could say that only W ratio and Y ratio are close ratio designs for sport cars although also Z ratio is used in American muscle cars. All in all every ratio set of Borg Warner Super T-10 have some realitionships with each other except Z ratio. This is because they have changed only few gear pairs between different ratio sets.

Picture links:	4-speed pic1	4-speed pic2	4-speed pic3	4-speed pic4

Picture links:	4-speed alter pic1	4-speed alter pic2	4-speed alter pic3	4-speed alter pic4	4-speed alter pic5 (no bricks)

Picture links:	4-speed alter2 pic1	4-speed alter2 pic2	4-speed alter2 pic3	4-speed alter2 pic4	4-speed alter2 pic5 (no bricks)

Picture links:	Ratios	Ratio comparison

LDraw files:	lego 4 prog 5.ldr	lego 4 prog 5 alter.ldr	lego 4 prog 5 alter2.ldr

Brickshelf Gallery:	Prog45

YouTube videos:	Building example (modified)

These lego version V setups are more complex than previous three version IV setups. But these ratio sets are very realistic with one exception: lego versions are all overdrive while Borg Warner’s gearboxes are direct drive. Check similarities in ratios and gear steps from picture Ratio comparison. So, these three lego setups are realistic designs for old American muscle cars and other sport cars but three setups of 4-speed version IV are simpler lego designs so it’s worth to consider to build one of them.

Actually, there is some uncertainty in these ratio set names. Web searches I have done showed that older Y ratio has same ratio set as newer CC ratio but newer Y ratio has faster second gear ratio. So, in my notations name Y ratio is reserved for that newer ratio set and older Y ratio has its newer name CC ratio. Nowadays this 4-speed Super T-10 transmission is manufactured by Richmond Gear (check link under title).

P.11. 4-speed version VI, overall gear ratios 2,45 & 2,14:

Inspirers: Muncie M20 (wide ratio) & M21 (close ratio)

These two setups of lego 4-speed version VI are inspired by Muncie’s old 4-speed transmissions M20 (wide ratio) and M21 (close ratio). Also these transmissions have been used in old American muscle cars. Despite that M20 is described as wide ratio both M20 and M21 are close ratio designs for sport cars when you compare them to typical personal car transmissions. Muncie’s M20 and M21 are identical designs except different constant gear pair ratio (from input axle to side axle), there are no changes in synchro gear pairs (from side axle to output axle) in gears 1-3. So wide ratio version has higher ratio in constant gear pair which makes top gear step 3-4 larger, changes all underdrive gears slower and increases overall gear ratio. But other gear steps are unchanged so underdrive ratios (1-3 & R) change as one block.

Picture links:	4-speed wide ratio pic1	4-speed wide ratio pic2	4-speed wide ratio pic3	4-speed wide ratio pic4	4-speed wide ratio pic5 (no bricks)

Picture links:	4-speed close ratio pic1	4-speed close ratio pic2	4-speed close ratio pic3	4-speed close ratio pic4	4-speed close ratio pic5 (no bricks)

Picture links:	Ratios	Ratio comparison

LDraw files:	lego 4 prog 6 wide.ldr	lego 4 prog 6 close.ldr

Brickshelf Gallery:	Prog46

YouTube videos:	Building example (modified)

But you can say that this little gear pair change makes these two Muncies completely different kind of transmissions. M21 close ratio design has lazier move offs but faster acceleration in high speeds due to small gear steps so it’s more like race transmission. M20 wide ratio has larger gear step 3-4 which leads to slower gears 1-3. So gears 1-3 give faster acceleration in allowed road speeds but 4th gear is more like fuel saving cruising gear and acceleration after shift 3-4 is not optimized.

In lego designs easiest way to copy Muncie’s ratio change would be overdrive gearbox with two different top gear ratios. But overdrive top gear leads to difficulties to arrange other gears with suitable ratios. So modification in lego setups has two steps: different ratio in 3rd gear after synchro parts and same gear step modification for gears 1-2 in front gear pairs before synchro parts. In picture Ratios changes are colored so it’s easier for you to judge how good lego setups follow Muncie’s modular design. All in all ratios in lego setups are quite close to Muncie’s real gearboxes, check picture Ratio comparison.

These 4-speed version VI:s follow inspirers’ ratios so they are only compact but not simple lego designs. If you need simpler design for American muscle car or other older sport car I recommend to check earlier three setups of 4-speed version IV inspired by Borg Warner.

P.12. 6-speed, overall gear ratio 5,95:

This gearbox is a big brother of the 5-speed gearbox version II, only difference is the added slower first gear. Overall gear ratio is normal for a 6-speed personal car, but the gear step 1-2 is a little bit too large for this gearbox’s gear step progression. This gearbox shows that it’s possible to build also a 6-speed gearbox with progressive gear steps, but the construction is quite complicated.

Picture links:

6-speed pic5 (no bricks)

6-speed pic6 (no bricks)

LDraw files:

lego 6 prog.ldr

Brickshelf Gallery:

Prog6

YouTube videos:

Building example 6-speed ver III & 7-speed ver II

P.13. 6-speed version III, overall gear ratio 4,29:

Inspirer: Aston Martin V12 Vantage

Note that 6-speed version II is light truck transmission, that’s why this one is version III. This version III is close ratio sport car transmission inspired by Aston Martin V12 Vantage. There are two alternative input axles in this lego design: direct drive setup is better for high speed lego motor but overdrive setup has more realistic ratio set while Aston Martin’s transmission is double overdrive. You can check differences in ratios and gear steps from picture Ratio comparison.

Picture links:

LDraw files:

Brickshelf Gallery:

Prog63Remake

YouTube videos:

This lego version is remake with simpler design and personal car ratio set is changed to close ratio sport car version. Original design is available on page Junkyard if you want to check it.

These remade 6-speed version III and 7-speed version II are sister designs with identical ratios and gear steps in top four gears. In lower gears 6-speeder has larger gear steps (stronger progression) to get suitable overall gear ratio.

P.14. 7-speed version II, overall gear ratio 5,00:

Inspirer: Aston Martin V12 Vantage

7-speed personal car or sport car manual transmissions are still quite rare but you can find them in some sport cars like Porsche 911, Chevrolet Corvette or Aston Martin V12 Vantage. While these sport car transmissions are close ratio versions overall gear ratios are only about 4,9-6,3 which is not much for 7-speed transmission. This 7-speed version II is not direct ratio copy of Aston Martin’s transmission but close enough to use Aston Martin as inspirer. There are two alternative input axles in this lego design: direct drive setup is better for high speed lego motor but overdrive setup is more realistic while Aston Martin and other sport cars have overdrive transmissions. You can check differences in ratios and gear steps from picture Ratio comparison.

Picture links:

7-speed pic5 (no bricks)

LDraw files:

lego 7 prog 2.ldr

Brickshelf Gallery:

Prog72Remake

YouTube videos:

Building example 6-speed ver III & 7-speed ver II

This lego version is remake with simpler design and ratio set is changed to close ratio sport car version. Original design is available on page Junkyard if you want to check it.

These remade 6-speed version III and 7-speed version II are sister designs with identical ratios and gear steps in top four gears. In lower gears 6-speeder has larger gear steps (stronger progression) to get suitable overall gear ratio.

P.15. 7-speed version III, overall gear ratio 5,95:

Here is another 7-speed lego design, this time personal car transmission. I was little surprised how simple version I managed to do. There are no pre-axles before synchro axles, only 3 gear pairs between 4 synchro axles. This time gear steps between higher gears are all small so there is only little progression but in lower gears there is larger increase between gear steps.

Picture links:

LDraw files:

Brickshelf Gallery:

Prog73

YouTube videos:

Also this gearbox is possible to use as double overdrive version: you just change input to second synchro axle. This modification changes all ratios but doesn’t affect to gear steps or overall gear ratio. This time 6-speed version is not practical while it will have too small overall gear ratio.

Picture links:

4x2-speed pic7 (no bricks)

7-speed alter pic1

P.16. 4x2-speed version A & B, overall gear ratio 4,90:

Inspirer: Mitsubishi Cordia Super Shift

Mitsubishi used this kind of transmission in late 70’s and 80’s. It’s based on normal 4-speed gearbox with progressive gear steps but contains also 2-speed auxiliary, which is splitter-type. Auxiliary’s shift lever has positions Power (low) and Economy (high). Altogether you have 8 gears but it’s difficult to use them all in upshifting procedure while every other shift would be difficult two stick shift. Typical use is to accelerate with Power mode and drive with Economy mode so you have 5 progressive gears. It is also handy in speed where upper gear has too low engine rpm but lower gear too high rpm while you can choose gear between them. If you drive in Economy mode and need to slow down a little or accelerate fast you can quickly downshift to Power mode and after situation upshift to Economy mode. While auxiliary shift is only forward/rearward movement there is no risk to shift to wrong gear.

Picture links:

Picture links:

4x2-speed B pic6 (axles only)

4x2-speed B pic7 (axles only)

4-speed DSG pic5 (no bricks)

LDraw files:

lego 4x2 prog.ldr

lego 4x2 prog b.ldr

Brickshelf Gallery:

Prog4x2Remake

YouTube videos:

Building example A & B

Original lego design is now replaced with much shorter design in which ratios and gear steps are closer to Mitsubishi’s Super Shift (check picture Ratio comparison). If you want to check old design it’s moved to page Junkyard. Now is available also version B with studless frame. While it has one special 1,75 stud axle base for gear pairs Su(12)-S(16) it’s simpler design than version A with brick frame.

In both lego versions gearboxes are located parallel which gives short design. So two transmission driving rings on the left belong to main gearbox and last one on the right to auxiliary. You can check shift levers from version B or YouTube video. In main shift lever axle left bush prevents axle to slide to left. Auxiliary shift lever uses axle pin and it prevents main shift lever axle to slide to right.

If you look close enough pictures of brick frame version you can notice that output axle is missing one bush. Mistake is corrected in LDraw file and YouTube video but it’s too much work to update all the pictures.

P.17. 3-speed & transfer case version VI, overall gear ratio 3,00:

Transfer case’s gear step 2,50
Inspirer: Willys Jeep

This transmission is based on old legendary off-road vehicle, Willys Jeep. It contains 3-speed main gearbox with reverse gear and 2-speed transfer case, which is part time 4x4. On the road vehicle is rear wheel drive but for difficult conditions you switch on front axle’s drive. While there is no centre differential in this transmission it’s not recommended to use 4x4 in good driving conditions. Transfer case has two shift levers: rear one is for low and high selection and front one switches front wheel drive on and off.

Picture links:	Ratios	3-speed TC6 pic1	3-speed TC6 pic2	3-speed TC6 pic3	3-speed TC6 pic4

LDraw files:	lego 3 prog tc6.ldr

Brickshelf Gallery:	Prog3TC6Remake

YouTube videos:	Building example (modified)

This 3-speed & transfer case version VI is remake with more compact design and better placed shift levers. Note that main gearbox contains two synchro axles on the left while right synchro axle belongs to transfer case. Original 3-speed & transfer case version III is now on page Junkyard. It’s worth to check if you want faster reverse gear that uses old 14 teeth thin bevel gears. Original design of transfer case version III is bad but there is alternative setup of it plus other transfer cases in chapter C. Transfer Cases on page Basic & special designs.

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[Links & Notes]

[A.-B.]

[C.-F.]

[G.-J.]

[K.-N.]

[O.]

[P.]

[Q.]

[R.]

[S.]

[T.]

[U.]

Q. Double Clutch Gearboxes:

Progressive gear steps
Inspirer: Personal cars

Double clutch gearbox or Direct shift gearbox (DSG) is an automatic personal car transmission with parts of manual transmission. It has 2 independent drive lines which are engaged alternately with double clutch unit. One drive line contains odd gears and another even gears. While one drive line is free of torque you can always preselect next gear before shifting. Shifting itself is only switching from one clutch to another so double clutch gearbox shifts very fast.

Like other personal car transmissions also double clutch gearboxes have progressive gear steps.

Next double clutch gearboxes need remote control shifting system but I don’t have parts to build and test such systems. So if you build remote control system for any of these gearboxes, let me know how to do it. :-) Essential in shifting system is that it shifts only free drive line but doesn’t affect to driven drive line. This way gears can be preselected which is the idea of double clutch gearbox.

Q.1. 4-speed, overall gear ratio 2,38:

This 4-speed double clutch gearbox is remake that has sport car’s close ratio ratio set. It’s also shorter and simpler design than original version. Original version is wide ratio design that suits better to diesel powered car so it’s moved to page Junkyard if you want to check it. Porsche has had 4-speed double clutch gearboxes in the 80’s but I haven’t found ratios of those gearboxes. While Porsche’s gearbox was race transmission my guess is that it’s close ratio design.

Picture links:

4-speed DSG pic6 (shift levers)

LDraw files:

lego 4-speed dsg remake.ldr

Brickshelf Gallery:

Prog4DSG1and2Remake

YouTube videos:

Building example 4-speed version I & II

While this lego version is not automatic you have to shift gears manually. Here is how it works: First you shift 1st gear with shift lever 1-3 and then move off with engaging drive line 1 in double clutch unit which is in input axle. While driving with 1st gear you preselect 2nd gear with shift lever 2-4. When it’s time to shift you only shift double clutch unit. Now in 2nd gear drive line 2 is active but 1st gear is still engaged. It’s time to disengage it and preselect 3rd gear. And again shifting happens with double clutch unit. 4th gear is shifted with same manner.

Lego version is not so handy as real double clutch gearbox but it’s remote control friendlier than truck or tractor gearboxes I have designed. With 3 small motors it’s possible to build remote control shifting system. Shifting mechanisms don’t have to stop in neutral while gears are preselected. Only time you need a neutral in double clutch unit is if you want to stop without stopping driving motor.

Building note: use only two bricks per axle (three with universal joint). There are coaxial axles in this design.

Q.2. 4-speed version II, overall gear ratio 3,33:

Operational principle of this version II is same as in previous double clutch gearbox so if you need information how it works check previous chapter.

Picture links:

4-speed DSG ver2 pic5 (shift levers)

4-speed DSG ver2 pic1

4-speed DSG ver2 pic2

4-speed DSG ver2 pic3

4-speed DSG ver2 pic4

LDraw files:

lego 4-speed dsg ver2 remake.ldr

Brickshelf Gallery:

Prog4DSG1and2Remake

YouTube videos:

Building example 4-speed version I & II

Also this one is close ratio design but gear steps and overall gear ratio are larger than in version I and suit to personal car transmission. Also this one is remake: ratio set is not changed but design is shorter and simpler than original which is available on page Junkyard.

Building note: use only two bricks per axle (three with universal joint). There are coaxial axles in this design.

Q.3. 7-speed, overall gear ratio 5,00:

Here is 7-speed version of double clutch gearbox. I found proper ratios for this transmission some time ago but it took some time before I finally designed it. I knew this gearbox wouldn’t be simple but final design is longer and more complicated that I wanted it to be. Actually gear connecting is as complex as in real double clutch gearbox but real version has automated use. While gears are divided to odd (drive line 1) and even (drive line 2) gears 6- and 8-speed versions need same number of synchro parts as this so they will be as complex as this 7-speed version.

Picture links:

7-speed DSG pic5 (shift levers)

7-speed DSG pic6 (drive lines)

LDraw files:

lego 7-speed dsg.ldr

Brickshelf Gallery:

Prog7DSG

Gear steps are small and overall gear ratio is only 5,00 so this gearbox is pure close ratio version.

This gearbox is used same way as previous 4-speed versions so check 4-speed double clutch gearbox version I to know how to use this. While this transmission has more gears it means that gear connecting synchro parts must be stopped also in neutral positions. For example in drive line 1 you can’t shift to 5th or 7th gear if 1st or 3rd gear is engaged, otherwise driveline will become locked. This is important feature if you want to build remote control version of this transmission.

Note: you may not see this in pictures but every axle has only two bearing points except output axle that has three bearing points due to universal joint. If you have difficulties to figure out this gearbox from pics download LDraw file.

Q.4. 6-speed, overall gear ratio 5,00:

This lego 6-speed double clutch gearbox is quite interesting construction: double clutch is made from synchro parts like in 4-speed versions but drive lines 1 & 2 are sequential sliding axle solutions. Compared to real double clutch gearbox this sequential structure is first difference, second is that drive lines don’t have neutral positions at all. Funny fact is that four ratios of this gearbox are integers and rest two have only one decimal.

Picture links:

6-speed DSG pic5 (shift levers)

LDraw files:

lego 6-speed dsg.ldr

Brickshelf Gallery:

Prog6DSG

YouTube videos:

6-speed DSG pic5 (shift levers)

Using this gearbox is almost same as shifting 4-speed versions. Here is how it goes: Before you move off make sure that 1st and 2nd gear are engaged. To move off engage drive line 1 with double clutch. While 2nd gear is already engaged you are ready to shift to 2nd gear, shifting itself is switching from one clutch to another. In 2nd gear you preselect 3rd gear in drive line 1 and then shift with double clutch. While in 3rd gear you preselect 4th gear in drive line 2 and again shift with double clutch. Then you repeat this until you reach top gear.

One notable thing is that drive line that is free of torque is rotated by output axle. So in low gears there is significant overdrive situation while rotating happens from rear to front. This can mean bad efficiency so after shifting to 2nd gear preselect 3rd gear immediately to get better efficiency. Maybe in 3rd gear is also wise to preselect 4th gear but in upper gears problem doesn’t occur.

And I found later that this gearbox could be 1 stud shorter: 16 teeth gear of drive line 2’s sliding axle won’t mesh with 16 teeth gear of output axle so they could be parallel. So you can also move drive line 1’s rear gears and rear brick segment 1 stud forward.

One interesting fact is that 6-speed sequential gearbox is not possible with legos because it’s too long construction, not even 5-speed is practical. But 2 parallel 3-speed sequential subgearboxes allow you to build 6-speed version. With this technic also 7- and 8-speed double clutch gearboxes are possible.

Q.5. 6-speed version II, overall gear ratio 5,00:

Here is another 6-speed double clutch gearbox that has synchro parts in double clutch but drive lines are sliding axle solutions. This time gearbox is double overdrive version. Conversion is done by changing gears that mesh with clutch gears from 24 teeth to 16 teeth. Other gear pairs are same as in previous version so this gearbox has same gear steps and overall gear ratio. Gears’ order is different because I first thought that I was creating totally new gearbox. This gearbox is used same way as previous 6-speed version so check it if you need more info about shifting.

Picture links:

LDraw files:

lego 6-speed dsg ver2.ldr

Brickshelf Gallery:

Prog6DSG2

While this is overdrive gearbox, ratios in lower gears are smaller than in direct drive version. This diminishes overdrive situation in lower gears in free drive line which is rotated by output axle. So possible efficiency problem in lower gears is not so essential. On the other hand overdrive top gear has poorer efficiency than direct top gear.

Q.6. 8-speed, overall gear ratio 6,75:

I got finally ready this 8-speed double clutch gearbox. It’s based on previous 6-speed gearboxes so check 6-speed version I for more information. This gearbox is a little bit long because I had difficulties to get all gear wheels into this construction. For example in output axle two 24 teeth gears where needed sequential by drive line 2 but drive line 1 needed gap between two 24 teeth gears so you actually needed three 24 teeth gears and lots of space.

Picture links:

8-speed DSG pic6 (shift levers)

LDraw files:

lego 8-speed dsg.ldr

Brickshelf Gallery:

Prog8DSG

Gear steps are not pure progressive while gear step 1-2 is same as 2-3 and again gear step 3-4 is same as 4-5. But otherwise there is progression so all in all you can say this gearbox has progressive gear steps. One notable thing is too small gear step 7-8 but without it I couldn’t get 8 gears. I have searched through many many gear pair combinations but it’s very difficult to get 8-speed gearbox with progressive gear steps. Other notable thing is that this gearbox has 3 overdrive gears so it’s possible that efficiency of the top gear is not very good while its ratio is as small as 0,67.

While input axle is supported by two technic brick 1x2 with 2 holes you may have difficulties to attach studded lego motor to the input axle. If you need hints to solve this problem check 4-speed version II in personal car transmissions (not in double clutch gearboxes). Reason for this arrangement is to get simpler shifting devices for drive line 1 and 2 by moving whole gearbox half stud sideways.

Q.7. 4-speed version III, overall gear ratio 3,27:

This 4-speed double clutch gearbox uses same technic as previous 6-speed versions so it has synchro double clutch and sliding axle drive lines. But this time there is a new feature: shifter that handles shifting of both drive lines.

Picture links:

4-speed DSG ver3 pic5 (shifter)

4-speed DSG ver3 pic1

4-speed DSG ver3 pic2

4-speed DSG ver3 pic3

4-speed DSG ver3 pic4

4-speed DSG ver3 pic6 (shifting devices)

LDraw files:

lego 4-speed dsg ver3.ldr

Brickshelf Gallery:

Prog4DSG3

Shifter’s idea is that it shifts only free drive line while driven drive line stays in gear. Shifter has positions 1-2, 3-2 and 3-4, and these positions are preselected while shifting itself happens with double clutch. Here is how it goes: Shifting from 1st gear to 2nd doesn’t need preselection, only switching from 1st clutch to 2nd. When you are in 2nd gear in upshifting procedure you change shifter’s position from 1-2 to 3-2. This changes gear in drive line 1 but doesn’t affect to drive line 2 and 2nd gear. When ready you shift with double clutch. While in 3rd gear you move shifter from position 3-2 to 3-4 (affects only to drive line 2) and you are ready to shift to 4th gear with double clutch.

[Back to top]

[Links & Notes]

[A.-B.]

[C.-F.]

[G.-J.]

[K.-N.]

[O.]

[P.]

[Q.]

[R.]

[S.]

[T.]

[U.]

R. Sequential Transmissions:

Here are sequential gearboxes which use sliding axle technic. Also these have progressive gear steps when number of gears is 3-5. There are now available also truck and tractor transmissions in which both main gearbox and auxiliaries are sequential. You can also check Project 5590 which is motorized model team truck with 12-speed transmission that contains 3 sliding axle gearboxes.

R.1. 4-speed, overall gear ratio 3,60:

This 4-speed sequential transmission has quite light progression while top step 3-4 is as large as 1,44 and step 1-2 only 1,67. So this could be used in diesel powered personal car. Design is double overdrive so it works best with low speed lego motor. It’s also lego builder friendly while there are no old 14 teeth thin bevel gears nor new 28 teeth double bevel gears.

Picture links:	Ratios	4-speed pic1	4-speed pic2	4-speed pic3	4-speed pic4

LDraw files:	lego 4 seq remake.ldr

Brickshelf Gallery:	Prog4SeqRemake

YouTube videos:	Building example 4-speed version I & II

This version is remake with two improvements: design is shorter while gear wheels take only 9 stud long space and ratio set is more realistic while underdrive top gear is changed to overdrive. Original design is moved to page Junkyard if you want to check it.

R.2. 4-speed version II, overall gear ratio 4,08:

4-speed Sequential Gearbox Version II Remake

This 4-speed version II is wide ratio design so it could be taken from diesel powered personal car. Progression is stronger than in version I so 1st gear is slower giving better climbing and load carrying capability. This design contains one new 28 teeth double bevel gear which is named ML (medium large) in my notations.

Picture links:	Ratios	4-speed pic1	4-speed pic2	4-speed pic3	4-speed pic4

LDraw files:	lego 4 seq 2 remake.ldr

Brickshelf Gallery:	Prog4Seq2Remake

YouTube videos:	Building example 4-speed version I & II

Also this one is improved remake: new design is simpler without extra side axle, shorter while gear wheels take 9 stud long space and easier to shift while there is double bevel type gear in every gear pair. Original design is still available on page Junkyard if you want to check it.

And as an interesting detail these 4-speed version I and II are modular designs with identical frames and gear wheel locating, only change is different gear wheels to get alternating ratio sets.

R.3. 4-speed version III, overall gear ratio 3,43:

This 4-speed sequential is not very short but it’s quite narrow and flat because it uses only 8, 12, 14 and 16 teeth gears. While number of possible ratios is limited I had to use side axle to get suitable ratio for 1st gear. Although this small design ratios, (progressive) gear steps and overall gear ratio are very typical for 4-speed gearbox. Top gear is overdrive and there is no direct gear in this gearbox.

Picture links:	Ratios	4-speed pic1	4-speed pic2	4-speed pic3	4-speed pic4

LDraw files:	lego 4 seq 3.ldr

Brickshelf Gallery:	Prog4seq3

YouTube videos:	Building example (modified)

R.4. 4-speed version IV, overall gear ratio 3,18:

Here is another quite small 4-speed sequential gearbox, 1 stud longer but even thinner than previous version III. Again it uses only 8, 12, 14 and 16 teeth gears and 1st gear has a side axle. Significant feature is that in 2 decimal accuracy this gearbox fits perfectly to the theory of progressive gear steps. (More info at Gearbox theories.) Now basic gear step is 1,36 and progression factor 1,08.

Picture links:	Ratios	4-speed pic1	4-speed pic2	4-speed pic3	4-speed pic4

LDraw files:	lego 4 seq 4.ldr

Brickshelf Gallery:	Prog4seq4

YouTube videos:	Building example (modified)

This is the first time I use 12 and 14 teeth gear pair in sliding axle solution. Normally I use them overlapped with same axle base as two 12 teeth gears. Now they are placed vertically so that there is one plate between bricks (0 LU;4 HU). I haven’t used this placement before.

R.5. 5-speed, overall gear ratio 5,00:

Despite what I earlier wrote about 5-speed sequential (too long), I decided to design one. Yes, it’s quite long for a single gearbox and sliding axle needs a lot of space before and after bearing points.

Picture links:	Ratios	5-speed pic1	5-speed pic2	5-speed pic3

LDraw files:	lego 5 seq.ldr

Brickshelf Gallery:	Prog5seq

YouTube videos:	Building example (modified)

My first 4-speed sequential has proper gear pairs for 5th gear but I didn’t use that construction while it’s underdrive and I wanted direct or overdrive version. Although it’s difficult to find good ratios that have progressive gear steps I found one interesting gear pair combination. It has two ratios that are too close to direct gear but proper gear steps in lower gears so if you forget direct gear you get good progressive gear steps. So this gearbox is overdrive version that has no direct gear.

I also found out that this gearbox could be 1 stud shorter. Here is how you can shorten gearbox: Change input’s axles to get axle joiner between 20 and 16 teeth gears. Then move input axle’s bush and two 12 teeth gears 1 stud rearward. Also move sliding axle’s 20 teeth gear right next to 12 teeth gear. Now you can move front brick segment 1 stud rearward.

R.6. 3-speed, overall gear ratio 2,88:

I haven’t designed 3-speed sequential gearbox before this version. It contains 3 important features in same gearbox so it was worth designing: it’s short while gear pairs take only 6 stud space between bricks, it has progressive gear steps and it doesn’t have S(16)-S(16) or XS(8)-S(16) gear pairs so it’s easy to shift.

Picture links:	Ratios	3-speed pic1	3-speed pic2	3-speed pic3	3-speed pic4

LDraw files:	lego 3 seq.ldr

Brickshelf Gallery:	Prog3seq

YouTube videos:	Building example (modified)

R.7. 3-speed version II B, overall gear ratio 2,84:

This 3-speed version II B uses Su(12)-S(16) gear pairs which can’t be supported by brick frame. So that’s why this gearbox has studless frame. This version IIB has same useful features as previous version I: gear pairs take only 6 stud longitudinal space inside frame, it has progressive gear steps and it doesn’t have S(16)-S(16) or XS(8)-S(16) gear pairs so it’s easy to shift.

Picture links:

3-speed pic5 (axles only)

LDraw files:

lego 3 seq 2b.ldr

Brickshelf Gallery:

Prog3seq2B

YouTube videos:

R.8. 3-speed version III B, overall gear ratio 3,33:

This 3-speed version III B uses only Su(12)-S(16) and XS(8)-Mu(20) gear pairs which means two things: There is always double bevel type gear wheel in gear pairs so gearbox is easy to shift. Secondly you need studless frame to support these axles. Again gear pairs need only 6 stud longitudinal space inside frame so structure is quite compact. Despite the few used gear pairs this gearbox still has some progression in gear steps. While overall gear ratio is closer to 4-speed gearbox than 3-speed this gearbox is wide ratio version.

Picture links:

3-speed pic1 (axles only)

3-speed pic2 (axles only)

LDraw files:

Brickshelf Gallery:

Prog3seq3B

YouTube videos:

R.9. 8-speed truck version B, overall gear ratio 8,33:

Main gearbox + splitter

This 8-speed sequential truck transmission has 4-speed main gearbox and splitter unit, both sliding axle versions. Sequential structure is not a problem while only splitter is shifted up and down during upshifting procedure, main gearbox goes only up and one gear at a time. If range-change unit was used situation would be more complicated while main gearbox would be shifted from 4th to 1st together with range change.

Picture links:

8-speed pic1 (axles only)

8-speed pic2 (axles only)

LDraw files:

Brickshelf Gallery:

8seqB

YouTube videos:

Also this transmission uses Su(12)-S(16) and XS(8)-Mu(20) gear pairs which can’t be supported by brick frame so this one has studless frame. All gear pairs have double bevel type gear wheel so this transmission is easy to shift. Gear steps are mainly 1,33 but two slowest compound shifts have step 1,41. Overall gear ratio is only 8,33 so this transmission is suitable for light and medium trucks only.

Note that in some pics main gearbox’s gear order is shown without splitter as 1-2-3-4. To be more accurate gear order is 1/2-3/4-5/6-7/8 where odd gears mean splitter low and even gears splitter high.

R.10. 8-speed truck version II, overall gear ratio 9,00:

Main gearbox + range

Here is 8-speed sequential truck transmission that has 4-speed main gearbox and range-change unit. It wasn’t easy to find proper ratios for main gearbox so this transmission is more complicated than previous 8-speed with splitter. But ratios of main gearbox became slightly progressive. Overall gear ratio is only 9,00 so this transmission is suitable for light and medium trucks only.

Picture links:

LDraw files:

Brickshelf Gallery:

8seq2

YouTube videos:

Sliding axle main gearbox with range-change unit is problematic combination because you have to shift main gearbox from 4th to 1st together with range shift. Normally it requires jump through 3rd and 2nd gear but I changed main gearbox’s gear order to 1-4-2-3. This way 5th gear (1st high range gear) is right next 4th gear but jumps are in shifts 1-2 and 3-4. When you think both ranges main gearbox’s gear order is 1/5-4/8-2/6-3/7 where first numbers mean low range and second high range.

R.11. 8-speed truck version III B, overall gear ratio 11,11:

Main gearbox + range

Here is another 8-speed sequential truck transmission that has 4-speed main gearbox and range-change unit. While this transmission has XS(8)-Mu(20) and Su(12)-S(16) gear pairs studless frame is the only choice. Again main gearbox has some progression in gear steps. Overall gear ratio (11,11) is a little bit larger than in previous 8-speed transmissions but only 8 gears mean that this is light and medium truck transmission.

Picture links:

8-speed pic1 (axles only)

8-speed pic2 (axles only)

LDraw files:

Brickshelf Gallery:

8seq3B

YouTube videos:

While this is overdrive transmission it works best with low speed motor. This transmission is not the smallest one so if you have lack of space check other sequential transmissions first. And if you have difficulties to figure out the construction from the pictures I recommend to download LDraw file or watch YouTube video Build it.

Once again main gearbox’s gear order is changed to 1-4-2-3 to get easier range shift. So all in all gears are in order 1/5-4/8-2/6-3/7 where first numbers mean low range and second high range.

R.12. 8-speed truck version IV, overall gear ratio 11,76:

Range + main gearbox

8-speed Sequential Truck Transmission Version IV

This one is modernized version of my 8-speed sequential truck transmissions that has 4-speed main gearbox and range-change unit. It doesn’t use any old 14 teeth thin bevel gears but two new 28 teeth gear wheels. So, gear wheels are larger than in earlier 8-speed versions but design is simpler while 28 teeth gears help to get typical gear steps for 8-speed transmission. Also this one is overdrive gearbox so it works best with low speed motor.

Picture links:

LDraw files:

Brickshelf Gallery:

8seq4

YouTube videos:

This time main gears are in logical order which means more complex range shift 4-5 while you have to shift both range-change unit and between main gears 1st and 4th (through 2nd and 3rd). Top gear step 7-8 is slightly too high 1,40 while largest top gear steps in trucks I have found are 1,37 but in lego world this is not a problem, or is it? :-) So, if you need sequential transmission for mid range truck and 8 gears are enough here simple and logical design for you.

R.13. 10-speed truck version B, overall gear ratio 9,89:

Main gearbox + splitter
Inspirer: Scania GS771

This 10-speed transmission is sequential version of M. 10-speed Transmission (with splitter) and it contains 5-speed main gearbox and splitter unit. Also this transmission has XS(8)-Mu(20) and Su(12)-S(16) gear pairs which need studless frame. While overall gear ratio is only 9,89 this transmission is for light and medium truck use only.

Picture links:

10-speed pic1 (upper axles)

10-speed pic2 (lower axles)

LDraw files:

Brickshelf Gallery:

10seqB

YouTube videos:

Note that gear order is not normal while 8th and 9th gear are swapped. Idea comes from Scania’s transmission and is to get halved gear steps for high speed driving meaning gear pairs 7-8, 8-9 and 9-10. So, gear order is 1/2-3/4-5/6-7/9-8/10 where first numbers mean splitter low and second splitter high.

R.14. 12-speed Twin Splitter truck, overall gear ratio 12,80:

Main gearbox + splitter
Inspirer: Eaton Twin Splitter

This 12-speed transmission is sequential version of J.1. 12-speed Twin Splitter. It has 4-speed main gearbox and 3-speed splitter but no reverse gears. This sequential version is smaller design than my original twin splitter while sequential main gearbox is not so wide as synchro version with reverse gear. So you can locate gearboxes parallel which means that long sequential main gearbox is not a problem.

Picture links:

12-speed Twin Splitter pic1

12-speed Twin Splitter pic2

12-speed Twin Splitter pic3

12-speed Twin Splitter pic4

12-speed Twin Splitter pic5

12-speed Twin Splitter pic6

LDraw files:

lego 12 seq ts.ldr

Brickshelf Gallery:

12seqTS

YouTube videos:

Ratios and gear steps of main gearbox are same as in my original setup but in splitter they are slightly different. Design also follows Eaton’s notation: gears are not 1-12 but main gears are 1-4 and splitter gears I-III. Sequential design is not very good in 3-speed splitter while in combined upshifts you have to shift main gearbox one gear up together with splitter shift from III to I (through II). But my original twin splitter had the same problem while its splitter is also sliding axle construction (H shift pattern in splitter would lead to 4x3 twin stick transmission).

R.15. 12-speed truck, overall gear ratio 12,50:

Main gearbox + range + splitter
Inspirer: Scania GRS895

This 12-speed sequential truck transmission contains 3-speed main gearbox, splitter and range-change unit. Gearboxes are located parallel so this transmission is very short but wide. Gears are 1L-1H-2L-2H-3L-3H-4L-4H-5L-5H-6L-6H.

Picture links:

LDraw files:

Brickshelf Gallery:

12seq

YouTube videos:

Gear steps are good while they vary only between 1,25-1,28 but overall gear ratio (12,50) is slightly small for the heaviest trucks. Range shift 3H-4L needs some attention while you have to upshift range, downshift splitter and downshift main gearbox from 3rd to 1st through 2nd gear. All gear pairs contain double bevel type gear or crown gear so this transmission is easy to shift.

While gear wheels take only 6 studs space you can think to put this transmission transversal between truck frame, input near to cabin and output axle next to driven axles. One solution is to support topmost axle with upper long bricks, use next bricks and plates as middle layer and support bottom axles with lower long bricks. It’s also useful to move input axle forward and locate it to either upper or lower long bricks.

If you need larger overall gear ratio you can check 12-speed transmission of Project 5590 or add crawler gear like in next two 14-speed transmissions.

R.16. 14-speed truck, overall gear ratio 20,00:

Main gearbox + range + splitter
Inspirers: Volvo VT2814B & Scania GRS905

This 14-speed sequential transmission is enlarged version of the previous 12-speed sequential transmission. Structure is slightly different compared to 12-speeder but for 12 gears ratios and gear steps are same in both versions. New feature is crawler gear (doubled by splitter) and its gear pairs which makes this transmission’s frame 4 studs longer than in 12-speed version. Also sliding axle of main gearbox needs some more space outside frame. Gears are CL-CH-1L-1H-2L-2H-3L-3H-4L-4H-5L-5H-6L-6H.

Picture links:

LDraw files:

Brickshelf Gallery:

14seq

YouTube videos:

lego 14 seq 2 into 13.ldr

While main gears are copied from previous 12-speeder also this transmission has good gear steps and it’s easy to shift due to used gear pairs. Structure is now longer but this transmission is still quite short, width is same as in 12-speed version. Now overall gear ratio (20,00) is large enough to be suitable for heavy trucks.

R.17. 14-speed truck version II, overall gear ratio 31,25:

Main gearbox + range + splitter, also 13-speed conversion
Inspirer: Volvo I-Shift with crawler gears

14-speed Sequential Transmission Version II

Here is another enlarged version of earlier 12-speed (2x3x2) sequential transmission. It’s sequential sister transmission of earlier A.4. 14-speed transmission version IV. This 14-speed sequential version II is inspired by Volvo I-Shift with crawler gears so its use differs from normal 14-speeder. In normal use this transmission is like typical 12-speed range-splitter transmission (2x3x2 design). But when low speeds are needed you choose splitter’s extra crawler position (CR) with main gearbox’s gears I or II. This crawler position overrides normal splitter so crawler gears have larger gear steps than in normal splitter type transmission. Overall gear ratio is large so this is heavy and severe duty transmission. Gears are C1-C2-1L-1H-2L-2H-3L-3H-4L-4H-5L-5H-6L-6H.

Picture links:

Picture links:

13-speed conversion pic1

LDraw files:

lego 14 seq 2.ldr

Brickshelf Gallery:

14seq2

YouTube videos:

16-speed pic7 (no bricks)

There is also a 13-speed conversion of this transmission. Conversion is simple swap in crawler gear’s gear pair. In 13-speed version splitter’s crawler position is selected with main gearbox’s 1st gear. This gives overall gear ratio 20,00 so transmission suits to heavy duty trucks. If you abandon splitter’s crawler position you get earlier shown 12-speed range-splitter transmission.

While there are no more than three gears in any gearbox gear wheels need only 6 studs space in this 14-speed transmission and its 13-speed conversion. Compared to earlier 12-speed transmission there is extra axle between range-change unit and splitter. So this transmission is short but wide. All gear pairs have double bevel type gear or crown gear so transmission is easy to shift.

All in all here is two good and compact designs with large overall gear ratio for lego gearbox builders who want sequential transmission or don’t have transmission driving rings.

R.18. 16-speed truck, overall gear ratio 16,33:

Splitter + range + main gearbox
Inspirer: ZF Ecosplit

I have had problems to make enough gear steps about 1,40-1,45 in sequential designs while you can’t always use 14 teeth thin bevel gears with sliding axles. But LEGO has released some time ago new 28 teeth gear wheel which I have named as ML (medium large) for my notations. With help of this new gear wheel new ratios allow this desired gear step for sequential design. So here is sequential 16-speed truck transmission that has splitter, range-change unit and 4-speed main gearbox. Gears are 1L-1H-2L-2H-3L-3H-4L-4H-5L-5H-6L-6H-7L-7H-8L-8H.

Picture links:

16-speed pic8 (no bricks)

LDraw files:

lego 16 seq.ldr

Brickshelf Gallery:

16seq

YouTube videos:

Main gearbox has quite large width and height due to large gear pairs but design is surprisingly short for 4-speed gearbox. Usually sequential 4-speed gearbox needs 10 stud length between bricks but this design takes only 8 studs. This time gears are in logical order so range change needs some attention while you have shift both range-change unit and between main gears 1st and 4th (through 2nd and 3rd). Splitter and range-change unit are underdrive and main gearbox overdrive but scaled ratios, gear steps and overall gear ratio are very realistic when compared to ZF Ecosplit.

If you have difficulties to figure out the construction from pictures I recommend to download LDraw file or check video Building example.

This transmission is sequential sister of K.1. 16-speed version I & K.3. 16-speed version III.

R.19. 16+16R-speed tractor, overall gear ratio 14,70:

Main gearbox + fwd/rev + range
Inspirer: John Deere 6430 PowrReverser (TractorData)

This transmission is sequential version for 16+16R-speed synchro tractor transmissions shown in S. Tractor Transmissions. It contains 4-speed main gearbox, driving direction changer and 4-speed range unit (ranges A-D). It is also a big brother of the next 12+4R-speed tractor transmission in which 4-speed main gearbox and driving direction changer are replaced with 3+R-speed main gearbox.

Picture links:

LDraw files:

lego 16 seq tractor.ldr

Brickshelf Gallery:

16seqtractor

YouTube videos:

Note that gear orders are illogical while front position has slowest gear in main gearbox but fastest range in range unit. This is because of compact design and driving direction changer which was difficult to locate between main gearbox and range unit. While driving direction changer uses spur gears XS(8) and S(16) it’s not very user friendly. So if you build this my guess is that you will use motor to change driving direction. But you can say that you have 32 different gears in your sequential transmission. :-)

Ranges overlap each other because range steps are relatively small: A-B and C-D are 2,00 and B-C is only 1,50. Idea of smaller B-C is taken from John Deere’s transmission and is to get more gears for field working speeds (4-12 km/h). In real tractors lots of gears in middle speeds mean that there are many speeds where you can take advantage of engine’s maximum power. In lego world lots of gears with small steps gives lots of different driving speeds. But in this transmission choosing right gear is quite confusing while in many cases sequential ratios are in different ranges, check table Ratios sorted in picture Ratios to see what I mean. And the idea is not to use all these gears in upshifting procedure while they would need difficult two stick shifts. John Deere’s recommended upshifting sequence from stop to full speed is (A1)-(B1)-C1-D1-D2-D3-D4 so you first upshift only ranges and after them only main gearbox’s gears. But if you want to keep things simple just choose first suitable speed range with range unit and then adjust speed with main gearbox.

R.20. 12+4R-speed tractor version A & B, overall gear ratio 10,80:

Main gearbox + range
Inspirer: John Deere 6430 SyncroPlus (TractorData)

This one is sequential version for 12+4R-speed synchro tractor transmission shown in S. Tractor Transmissions. It contains 3-speed main gearbox with reverse gear and 4-speed range unit (ranges A-D) so altogether you got 12 forward and 4 reverse gears. Using this transmission is quite simple while you first choose suitable speed range with range unit and then fine tune speed with main gearbox’s gears or choose to reverse. Available also version B with studless frame.

Picture links:

12-speed tractor pic6

Picture links:

12-speed tractor ver B pic1 (axles only)

12-speed tractor ver B pic2 (axles only)

12-speed tractor ver B pic3

12-speed tractor ver B pic4

12-speed tractor ver B pic5

12-speed tractor ver B pic6

12-speed tractor ver B pic7

12-speed tractor ver B pic8

LDraw files:

lego 12 seq tractor.ldr

lego 12 seq tractor b.ldr

Brickshelf Gallery:

12seqtractor

YouTube videos:

Building example A (modified)

Building example B

Ratios and gear steps of range unit are same in synchro and sequential versions but in main gearboxes ratios vary a little while you can’t copy ratios of synchro version to sequential design. Once again range step B-C (1,50) is smaller than steps A-B and C-D (2,00). Reason comes from real tractors and is to get more gears suitable for field working speeds (4-12 km/h). While this transmission has two 4-speed gearboxes located to parallel design is quite compact for a sequential gearbox that has so many gears. And that is not all while you can add splitter (in real tractor powershift) or creeper unit to this transmission so you can get 24+8R-speed and 21+7R-speed versions.

R.21. 6+3R-speed tractor, overall gear ratio 12,00:

Main gearbox + range

This lego 6+3R-speed sequential tractor transmission doesn’t have direct inspirer while it’s combined from two kind of tractor transmissions. First one is Massey Ferguson’s 6+2R-speed which has 3-speed main gearbox with reverse gear together with 2-speed range unit. Second one is Ford’s 8+4R-speed which has four main gears plus ranges high, low and reverse (2+R-speed). In lego design three main gears are taken from Massey Ferguson and 2+R-speed auxiliary from Ford.

Picture links:

6-speed tractor pic6 gear selection

LDraw files:

lego 6 seq tractor.ldr

Brickshelf Gallery:

6seqTractor

YouTube videos:

8-speed tractor alter2 pic1

In lego design idea is to get maximum number of gears with minimum size by using only two 3-speed sequential gearboxes. So if you have difficulties to fit transmission to your lego tractor and need sequential design here is small setup for you.

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S. Tractor Transmissions Part I:

Here is first part of tractor transmissions. In notation for example 8+4R means that transmission has 8 forward and 4 reverse gears. Transmissions can be arranged many different ways so for example 12 forward gears can mean 3 main gears with 4 ranges, 4 main gears with 3 ranges or 6 main gears with 2 ranges. And reverse gear can be integrated in main gearbox, range unit or splitter, or there can be separate driving direction changer which is called shuttle in real world. In real tractors they don’t usually give transmission ratios but example driving speeds with certain engine rpm and tyre size. In this case gear step = speed upper gear / speed lower gear.

In lego tractors idea is that in long and narrow inline setups you hide motor and front part of the transmission into tractor’s engine bay and only rear parts are between rear tires under or inside cabin. And in short and wide parallel setups you put wide part of the transmission between rear tires under or inside cabin.

Some tractor transmissions have powershift which can be shifted under load by push of a button without cutting the torque in drive line. Real tractors’ powershift is not possible with legos, lego powershift needs two or more identical motors and at least one planetary gear so in some cases I have used splitter instead. These lego “splitters” are representing powershifts’ small speed changes instead of main gearbox shifting. Some real tractors have mechanical splitters for more accurate working speed control but these are not designed for splitting all main gears in upshifting procedure like truck splitters. More info about powershift is in chapter S.1. 8+4R-speed & 16+8R-speed.

I have designed also sequential tractor transmissions which are located in chapter R. Sequential Transmissions. It’s worth to check also B.7. 15+6R-speed planetary gear set for tractor (theoretical only) and C.9. 9+9R-speed full powershift tractor transmission (usable) in page Planetary gears.

S.1. 8+4R-speed & 16+8R-speed , overall gear ratios 11,43 & 14,29:

8+4R: main gearbox + range
16+8R: powershift + main gearbox + range
Inspirer: Ford 6610 Dual-range & Dual Power (TractorData)

I met this kind of 8+4R-speed transmission in my teenage years when I drove shortly one Ford tractor (I don’t remember model number any more). This tractor was rear wheel drive and its top speed was 30 km/h. It had 4-speed main gearbox without a reverse gear plus range unit with ranges high, low and reverse. So altogether you’ve got 4 slow and 4 fast gears in forward plus 4 slow gears in reverse.

This kind of transmission is ideal when you have to drive slow and change often driving direction. The idea is to choose suitable gear in main gearbox and then use only auxiliary. On the other hand this kind of transmission isn’t good at high speed driving although you can move off as high gear as 7th if you are unloaded and slide the clutch a little. When you have driven with 8th gear and need to reverse you simply choose gear R4 with auxiliary shift lever. But to drive forward fast again you have to shift with the both sticks to get 5th, 6th or 7th gear, which are suitable gears to move off.

Picture links:

Ratios alter2

8-speed tractor alter2 pic2

8-speed tractor alter2 pic3

8-speed tractor alter2 pic4

8-speed tractor alter2 pic5

8-speed tractor alter2 pic6

LDraw files:

lego 8-speed tractor alter2.ldr

Brickshelf Gallery:

8spdtractor

YouTube videos:

Building example alter2 (modified)

Here is shown only 8+4R-speed alternative setup II (alter2) with redesigned auxiliary. Original inline setup and alternative parallel setup are moved to page Junkyard because I designed those earlier setups before finding typical ratios of 8+4R-speed transmission. So step between low and high range was too large and reverse gears were too slow. Alternative setup II has more realistic auxiliary ratios. Modification also makes transmission slightly simpler and more compact than original setup. Range unit can be also equipped with faster low and reverse range without losing reality. This alternative ratio set is used in next 16+8R-speed.

This 16+8R-speed is otherwise like 8+4R-speed transmission but like Ford’s transmission it’s equipped with additional 2-speed powershift. This doubles the number of gears and allows shifting between Hi and Lo under full throttle.

Picture links:

16-speed tractor pic6 (no bricks)

16-speed tractor pic7 (no bricks)

Picture links:

LDraw files:

lego 16-speed tractor remake.ldr

Brickshelf Gallery:

16spdTractorRemake

YouTube videos:

8-speed tractor pic5 (no bricks)

This 16+8R-speed lego design is remake with two improvements: splitter is replaced with lego powershift and too slow reverse ratios in range unit are changed to more realistic. So after update old original inline and alternative parallel setups are moved to page Junkyard if you want to check them.

Lego powershift is done by two identical motors and planetary gear version II with basic ratio 4,00. You get powershift stage low by running only motor 1 (M1) while motor 2 (M2) is stopped, this gives ratio 1,33. In stage high both motors are run in same direction to get direct ratio 1,00. More info about this lego powershift is in chapter B.9. 2-speed powershift for tractor on page Planetary gears.

There is also a cousin 8+4R-speed transmission in E. Flat Gearbox Designs, page Basic & special designs.

All in all Ford is not the only manufacturer that has 8+4R-speed transmission, also Valmet/Valtra and John Deere have their own versions. 8+4R-speed is basic transmission which can be enlarged with powershift, mechanical splitter or creeper unit. It depends on manufacturers which enlargements are available. This 16+8R-speed is inspired by Ford’s powershift transmission and later shown 16+8R-speed & 12+8R-speed by Valmet’s versions with mechanical splitter or creeper unit.

What is powershift?

Powershift is gearbox which can be shifted with button under load without cutting the torque in drive line and without need to press clutch pedal. Powershift is close to splitter while both have small gear steps and are used by buttons but their use is completely different: splitter is preselected and allows to split all main gearbox’s gears but powershift shifts instantly and is normally used only once during upshifting procedure. Typically you move off with powershift in low but drive powershift in high. So if you have to slow down or engine rpm drops because of high load you can quickly downshift under full throttle with powershift to get more torque and engine rpm back in working range. When situation is over you shift back to high and get more speed. Powershift is handy for example in ploughing when driving resistance is so high that normal shifting with main gearbox ends to tractor’s complete stop before you get a new gear.

Powershift is not designed for this but if you want to split main gearbox’s gears with powershift, for example shift from 5H to 6L, it is possible so that you downshift with powershift when clutch pedal is pressed down for main gearbox’s upshifting. But in many tractors powershift’s gear step is more than half of main gear steps so powershift splits gears too unequal and this maneuver is not practical. But there are also tractor transmissions in which powershift gives halved steps so this powershift splitting is in theory possible.

While powershift can shift without cutting the torque in drive line it can’t be constantmesh or synchromesh gearbox. Normally powershift’s gear coupling is done by multiplate wet clutches and pressurised oil which means poorer efficiency than in constantmesh or synchromesh gearbox. That’s why tractors usually have only few powershift gears together with constantmesh or synchromesh main gearbox and range unit.

Although real powershift gearbox is not possible with legos you can build lego 2- or 3-speed powershift that uses 2 identical motors and a planetary gear. Check for example C.7. 3-speed powershift for tractor version II on page Planetary gears for more information. If you use 3 motors and 2 planetary gears you can build simpler 5-speed powershift or complete 9+9R-speed powershift transmission. Check C.8. 5-speed powershift for tractor and C.9. 9+9R-speed full powershift tractor transmission in same link.

S.2. 8+2R-speed & 16+4R-speed, overall gear ratios 10,50 & 13,99:

8+2R: range + main gearbox
16+4R: powershift + range + main gearbox
Inspirer: Ford 6610 Dual-range & Dual Power (TractorData)

This basic 8+2R-speed tractor transmission (8-speed tractor version II) has 4-speed main gearbox with reverse gear and 2-speed range unit. 16+4R-speed version has additional 2-speed powershift which doubles the number of gears and allows shifting between Hi and Lo under full throttle.

Picture links:

8-speed tractor pic6 (no bricks)

LDraw files:

lego 8-speed tractor ver2.ldr

Brickshelf Gallery:

8and16spdTractor

YouTube videos:

Building example 8-speed & 16-speed

When you look lego design and ratios you can see that design is not the simplest, gear steps vary very much and shift pattern is not standard. Well, this is on purpose while ratios and shift pattern are copied from real Ford’s transmissions. Here is my guess, why gear steps vary so much in Ford’s transmissions: Gears 1st and 2nd are for low speed operating, then there is larger step 2-3 to squeeze four gears (3-6) into typical field working speeds 4-12 km/h. Then there is again larger step 6-7 (same as step 2-3 due to range unit) before transportation gears 7th and 8th. This time larger step ensures that you reach allowed top speed 30 km/h with 8th gear. So, it’s possible that large varying in gear steps is on purpose, not because of bad designing.

Picture links:

16-speed tractor pic6 (no bricks)

16-speed tractor pic7 (no bricks)

Picture links:

LDraw files:

lego 16-speed tractor ver5.ldr

Brickshelf Gallery:

8and16spdTractor

YouTube videos:

Building example 8-speed & 16-speed

16+4R-speed version (16-speed tractor version V) has same Hi-Lo powershift as previous 16+8R-speed transmission. You get powershift stage low by running only motor 1 (M1) while motor 2 (M2) is stopped, this gives ratio 1,33. In stage high both motors are run in same direction to get direct ratio 1,00. More info about this lego powershift is in chapter B.9. 2-speed powershift for tractor on page Planetary gears.

So, these 8+2R-speed and 16+4R-speed are complex lego designs while they copy ratios and shift pattern from real Ford’s transmissions. If you need more basic lego design with good geometrical gear steps you can build next main gearbox and range unit combination from page Basic & special designs: A.3. Range-change unit, gear step 4,00 & B.6. 4+R-speed synchromesh gearbox, overall gear ratio 3,00. They give usable 8+2R-speed design which can enlarged to 16+4R-speed with this same Hi-Lo powershift.

S.3. 16+8R-speed & 12+8R-speed, overall gear ratios 12,86 & 42,86:

16+8R: splitter + main gearbox + range
12+8R: creeper + main gearbox + range
Inspirer: Valmet 900 (TractorData)

16+8R-speed Tractor Transmission Version II

These two tractor transmissions are based on 8+4R-speed transmission which has 4 main gears together with ranges high, low and reverse. Also Valmet (nowadays Valtra) has had this kind of transmission and they offered two optional equipment: either mechanical splitter or creeper unit but not both. Splitter doubles the number of gears to 16+8R-speed, halves the gear steps and it’s for more accurate working speed control (not practical to split gears in upshifting procedure). Creeper unit enlarges overall gear ratio and gives four extra slow gears in both driving directions so you got 12+8R-speed design. Creeper unit can be switched on with ranges low and reverse.

Picture links:

Ratios 16-speed

16-speed tractor pic6

16-speed tractor pic7

Picture links:

lego 16-speed tractor ver4.ldr

12-speed tractor pic6

12-speed tractor pic7

LDraw files:

lego 12-speed tractor ver3.ldr

Brickshelf Gallery:

16and12spdTractor

YouTube videos:

In lego versions 16+8R-speed is new design (16+8R-speed version II, 16-speed tractor version IV) but 12+8R-speed (12-speed tractor version III) is remake. Original 12+8R-speed designs (original inline & alternative parallel setup) are moved to page Junkyard and they are junked due to too slow reverse gears and badly placed creeper shift levers. New 16+8R-speed and 12+8R-speed are based on same lego 8+4R-speed transmission which is S.1. 8+4R-speed with alternative ratio set in range unit. But adding splitter or creeper unit makes these two very different kind of transmissions: 16+8R-speed gives small steps and 12+8R-speed extra slow speeds. So depending on your lego tractor you can choose which enlargement to use, or you can use basic 8+4R-speed.

These 16+8R-speed and 12+8R-speed transmissions have also cousin designs with slightly different range ratios in section E. Flat Gearbox Designs on page Basic & special designs.

S.4. 18+6R-speed, overall gear ratio 22,68:

3-speed main gearbox + splitter + 3-speed range
Inspirer: Massey Ferguson 4270 Speedshift

This inspirer has 3-speed main gearbox with a reverse gear, 3-speed range unit (ranges A, B and C) and Hi-Lo powershift. Altogether you have 18 forward gears and 6 reverse gears. In lego version powershift is replaced with splitter. If you need more information about powershift check earlier 16+8R-speed tractor transmission.

Picture links:

18-speed tractor pic6 (no bricks)

18-speed tractor pic1

18-speed tractor pic2

18-speed tractor pic3

18-speed tractor pic4

18-speed tractor pic5

18-speed tractor pic7 (no bricks)

LDraw files:

lego 18-speed tractor.ldr

Brickshelf Gallery:

18spdtractor

YouTube videos:

6-speed tractor pic6 (no bricks)

This time both real transmission’s powershift and lego version’s splitter split main gearbox’s gears equally, so you can split gears like in truck transmission if you need halved gear steps. But actually Massey Ferguson’s powershift is for slower move off gear before powershifting to higher driving gear in high driving resistance working like ploughing. Lego version’s splitter can be used to same small speed changes without powershift, other use is more accurate working speed control than without splitter. It’s also possible to add lego motor on splitter’s shift lever axle. This way you can get remotely button shifted splitter which is a little bit closer to real world’s powershift than manual lego splitter.

One interesting thing is that Massey Ferguson’s range change is integrated to main gearbox’s H shift pattern. So if you drive for example in B range’s top gear and need to change range, you shift main gearbox to neutral, move shift lever to right for range selection, push forward to change to C range and then move back left to shift to main gearbox’s first gear. With this system you avoid difficult two stick shift. Lego version is not so handy so you have to shift both range’s and main gearbox’s shift levers to make simiral shift. But this is not a problem in lego world while you stop for shifting if you don’t have remote controlled gearboxes.

I found also a building mistake: topmost axle in splitter and range unit has 3 support points which is too many (2 support points is enough). So if you build this transmission, forget the middle support point or use universal joint. In modified building example this error is corrected.

S.5. 6+2R-speed & 12+4R-speed, overall gear ratios 12,00 & 16,00:

6+2R: range + main gearbox
12+4R: powershift + range + main gearbox
Inspirer: Massey Ferguson 150 (TractorData)

These two transmissions are inspired by old Massey Ferguson 150. 6+2R-speed has 3-speed main gearbox with reverse gear plus 2-speed range unit. 12+4R-speed has same gearboxes but also 2-speed powershift which allows shiftings between Hi and Lo under load without cutting torque in drive line.

Picture links:

Picture links:

12-speed tractor pic6 (no bricks)

Picture links:

LDraw files:

lego 6-speed tractor.ldr

lego 12-speed tractor ver5.ldr

Brickshelf Gallery:

6and12spdTractor

YouTube videos:

Lego powershift is done with two motors and a planetary gear. You get powershift stage low by running only motor 1 (M1) while motor 2 (M2) is stopped, this gives ratio 1,33. In powershift high you run both motors in same direction to get direct ratio 1,00. More info about this lego powershift is in chapter B.9. 2-speed powershift for tractor on page Planetary gears.

For shift levers use three longitudinal bricks. Use six studs axle for main shift lever and put bush to right side of the left brick. Put middle brick between main gearbox and range unit, it’s main shift lever’s right support. Use right brick and axle pin to support range shift lever. This design is enough to prevent main shifter axle to slide to left or right.

These transmissions use very basic lego ratios so main gearbox and range unit have very compact parallel design. So if you have lack of space to add gearbox it’s worth to test these two transmissions, especially basic 6+2R-speed version. If you need small tractor transmission but don’t have transmission driving rings I recommend to check 6+3R-speed tractor in section R. Sequential Transmissions.

S.6. 12+12R-speed, overall gear ratio 13,89:

2-speed range + shuttle + 6-speed main gearbox
Inspirer: Massey Ferguson 4608

12+12R-speed Tractor Transmission Remake

This tractor transmission has 6-speed main gearbox, 2-speed range unit and driving direction changer which is called shuttle in real world. Altogether you’ve got 12 forward gears and 12 reverse gears, which means that you can drive rearward as fast as forward if you have the guts.

Picture links:

12-speed tractor pic5 (no bricks)

LDraw files:

lego 12-speed tractor remake.ldr

Brickshelf Gallery:

12spdTractorRemake

YouTube videos:

This lego design is remake which is more compact and more realistic three-range design with better ratio set than original design. In original lego design range unit and driving direction changer are combined to one auxiliary. Original design is moved to page Junkyard due to better remake but actually it’s not bad design at all. All in all this remake is quite basic lego design but still realistic tractor transmission.

Massey Ferguson’s driving direction changer is a power shuttle, which means that in low speeds you can change driving direction simply moving changer’s shift lever, no stopping nor clutch pedal is needed during operation. In lego transmission driving direction changer is more like mechanical shuttle with synchro shifts. Actually it’s not needed while lego motor works in both directions but this way you get more realistic transmission to your lego tractor.

Also Valtra A series has 12+12R-speed transmission that has 6 main gears with 2 ranges.

S.7. 12+12R-speed version II, overall gear ratio 21,00:

4-speed main gearbox + shuttle + 3-speed range
Inspirer: AGCO Allis 6690 (TractorData)

This 12-speed tractor transmission version II has 4-speed main gearbox, driving direction changer (shuttle) and 3-speed range unit (ranges A, B and C). Altogether you’ve got 12 gears in both driving directions. Driving direction changer is not necessary in lego world but it fitted perfectly between main gearbox and range unit: sliding axle solution of range unit needs anyway some space in front it.

Picture links:

12-speed tractor pic4 (no bricks)

12-speed tractor pic5 (no bricks)

12-speed tractor pic6 (no bricks)

LDraw files:

lego 12-speed tractor ver2.ldr

Brickshelf Gallery:

12spdtractor2

YouTube videos:

One notable thing is that lego version’s overdrive main gearbox is not very practical in tractor use because slow speeds and large tires require large ratio in final drive. Problem is that I don’t know other way to make gear step 1,33 than overdrive gearbox. I found later how to make gear step 1,31 that makes not an overdrive gearbox but it was too late for this transmission. And I have found out that they use overdrive gearboxes also in tractor transmissions together with high reduction planetary gears in final drives. So lego design ain’t so bad design after all.

Note that bush in the end of output axle is not in good place, 24 teeth crown gear will hit it when you slide the axle. Better place is at the front end next to two 24 teeth gears. I’m too lazy to fix the LDraw file and pics. In modified Building example this problem is fixed.

In real world this kind of 4x3-structure is simpler, shorter and older (my guess) than 6x2-construction. 4x3 needs 7 gear pairs when driving direction changer is not included while 6x2 needs 8 gear pairs. Lego version is not shorter but thinner because more gears in main gearbox would increase its width not length. Also 3-speed sliding axle range unit needs more longitudinal space than 6x2-version’s auxiliary.

When I have investigated tractor brochures I have found out that this 4x3-structure 12+12R-speed can be quite common design. This lego version is inspired by AGCO Allis but for example Ford and Massey Ferguson also have this kind of design. Probably also Valtra has their own version while 36+36R-speed powershift transmission has 4 main gears with 3 ranges.

S.8. 16+16R-speed, overall gear ratio 14,00:

4-speed main gearbox + shuttle + 4-speed range
Inspirer: John Deere 6430 PowrReverser (TractorData)

16-speed Tractor Transmission Version II

This tractor transmission has 4-speed main gearbox, driving direction changer (shuttle) and 4-speed range unit (ranges A, B, C and D). Altogether you have 16 gears in both driving directions.

Picture links:

lego 16-speed tractor ver2 remake.ldr

16-speed tractor pic6

LDraw files:

Brickshelf Gallery:

16spdTractor2Remake

YouTube videos:

Range steps are relatively small so ranges overlap each other, especially ranges B and C. Major idea in this overlapping is that you get large variety of gears for field working speeds with small steps. But choosing right gear is not always easy while sequential gears are often in different ranges. Check Ratios sorted in picture Ratios. These small steps are only for working speed control, not for upshifting procedure. But small range steps allow you to change range while driving without main gearbox shifting. This way you can avoid difficult two stick shift. For example in heavy loaded transport situation John Deere recommends upshifting sequence (A1)-(B1)-C1-D1-D2-D3-D4.

This lego design is remake in which range steps A-B and C-D are 2,00 and step B-C is only 1,50. In original design all range steps are 2,00 while I didn’t first realize how clever John Deere’s 16+16R-speed transmission is. So after modification I got simpler and more compact range unit with more realistic ratio set. Original lego design is still available on page Junkyard if you want to check it.

Although this transmission and earlier 12+12R-speed transmission version II are inspired by different tractors, main gearbox’s ratios of 12-speed transmission fitted perfectly to this 16-speed transmission. So this transmission’s main gearbox and driving direction changer are taken directly from 12-speed transmission, the only new part is 4-speed range unit. It reduced a lot LDraw file design time. On the other hand main gearbox is again overdrive version which is not so practical in tractor use.

In this remake shift levers are located quite front close to each other. Idea is that you hide shift levers inside tractor’s engine bay and pop the hood for shifting. So this time you can build realistic cabin above range unit’s axles.

S.9. 16+16R-speed version II, overall gear ratio 13,78:

Shuttle + 4-speed range + 4-speed main gearbox
Inspirer: John Deere 6430 PowrReverser (TractorData)

16+16R-speed Tractor Transmission Version II Alternative Setup II

Also this 16+16R-speed tractor transmission version II (16-speed tractor version III) has 4-speed main gearbox, 4-speed range unit (ranges A-D) and driving direction changer alias shuttle. Unlike previous version I this transmission has synchro range unit, sliding axle driving direction changer and direct drive main gearbox. So this one is more like next 12+4R-speed and its upgraded version 21+7R-speed. Available is two alternative setups, short but wide parallel setup alter and long but narrow inline setup alter2, and both have double bevel type gear wheel in driving direction changer for easier use. For shift lever axles in parallel setup put longitudinal brick with holes also between main gearbox and range unit and axles only half studs inside middle brick.

Picture links:

16-speed tractor alter pic1

16-speed tractor alter pic2

16-speed tractor alter pic3

16-speed tractor alter pic4

16-speed tractor alter pic5

16-speed tractor alter pic6

Picture links:

Ratios alter2

16-speed tractor alter2 pic1

16-speed tractor alter2 pic2

16-speed tractor alter2 pic3

16-speed tractor alter2 pic4

16-speed tractor alter2 pic5

LDraw files:

lego 16-speed tractor ver3 alter.ldr

lego 16-speed tractor ver3 alter2.ldr

Brickshelf Gallery:

16spdtractor3

YouTube videos:

Building example alter2 (modified)

Like in previous 16+16R-speed ranges overlap each other, and range step B-C is smaller than others. Idea is copied from John Deere’s transmission and is to get more gears for field working speeds (4-12 km/h). When you sort gear ratios you can see that there are good small gear steps in middle gears so you can get right speed for every working situation. But choosing right gear is not so easy while most of the sequential gears are in different ranges, check table Ratios sorted in picture Ratios. These small steps are for working speed control and you are not supposed to use all these gears in upshifting procedure, two stick shifts are just too complex. John Deere’s recommended upshifting sequence from stop to full speed is (A1)-(B1)-C1-D1-D2-D3-D4. Because range steps are larger than steps of main gearbox you upshift between ranges first. But you can always keep things simple so that you choose first suitable speed range with range unit and then use only main gearbox and driving direction changer.

Changing between forward and reverse is these lego designs’ weak point while driving direction changers are sliding axle versions. Especially original setup has problematic XS(8)-S(16) spur gear design so due to bad usability it’s moved to page Junkyard if you want to check it. Alternative setups are a little bit easier to use while they have Su(12) double bevel type gear on the sliding axle. When main gearbox and range unit are synchro versions 3rd synchro gearbox would be too much because of the backlash problems. So I guess that those who will build this transmission will use motor to change driving direction.

S.10. 12+4R-speed & 21+7R-speed, overall gear ratios 10,50 & 63,00:

12+4R: 4-speed range + 3-speed main gearbox
21+7R: creeper + 4-speed range + 3-speed main gearbox
Inspirer: John Deere 6420 SyncroPlus (TractorData)

This 12+4R-speed tractor transmission is a little brother of previous 16+16R-speed transmission version II. Both have 4-speed range unit (ranges A-D) but 4-speed main gearbox and driving direction changer are now replaced with 3-speed main gearbox that has also a reverse gear. While this transmission has only 2 gearboxes which have only 4 positions in shift patterns this transmission is quite compact structure. Note that right synchro axle of main gearbox has only 2 support points so it doesn’t go inside range unit’s rear support brick.

Picture links:

Picture links:

12-speed tractor alter pic1

12-speed tractor alter pic2

12-speed tractor alter pic3

12-speed tractor alter pic4

LDraw files:

lego 12-speed tractor ver4.ldr

lego 12-speed tractor ver4 alter.ldr

Brickshelf Gallery:

12spdtractor4

YouTube videos:

There is available also alternative setup in which main gearbox and range unit are located parallel. For shift lever axles use longitudinal brick with holes between gearboxes and put axles only half studs inside it. This brick comes very close to range unit’s 24 teeth gear but they shouldn’t hit each other. If hitting becomes a problem you have to test 24 teeth crown gear, move XS(8)-M(24) gear pair outside of the frame or use 9 studs long beam instead of brick.

In these transmissions ranges B and C overlap each other but other ranges don’t although gear steps are very small between lower range’s top gear and higher range’s 1st gear. Overall gear ratio of one range is quite small but you can change range without main gearbox shifting while range steps are quite small too. In lego version steps A-B and C-D are 2,00 and while step B-C is only 1,50. Reason why range step B-C is smaller than the others comes from real world’s farm tractors and is to get more gears for speed range 4-12 km/h which is usual speed range for field working. If tractor’s top speed is about 30 km/h needed ratios are between 2,50-7,50.

There is also available a sequential version of this transmission. Check 12+4R-speed tractor in R. Sequential Transmissions for more info.

John Deere offers creeper unit as optional equipment for 12+4R-speed transmission. Creeper unit can be used with 3 lowest ranges giving creeper ranges LA, LB and LC. This gives 9 very slow speed gears in forward and 3 in reverse so altogether you get 21 forward and 7 reverse gears. So available is lego version of 21+7R-speed transmission, based on alternative setup of 12+4R-speed transmission.

Picture links:

lego 21-speed tractor.ldr

21-speed tractor pic1

21-speed tractor pic2

21-speed tractor pic3

21-speed tractor pic4

21-speed tractor pic5

21-speed tractor pic6

LDraw files:

Brickshelf Gallery:

21spdtractor

YouTube videos:

S.11. 12+4R-speed & 24+8R-speed, overall gear ratios 8,93 & 10,71:

12+4R: main gearbox + range
24+8R: powershift + main gearbox + range
John Deere 9400 Syncro & PowrSync (TractorData)

12-speed Tractor Transmission Version VI

These two lego transmissions are inspired by John Deere 9400 monster tractor. 12+4R-speed transmission has 3-speed main gearbox with reverse gear together with 4-speed range unit (ranges A-D). 24+8R-speed has also additional Hi-Lo powershift which doubles the number of gears. In John Deere’s transmissions range D is not available in reverse so they are 12+3R-speed and 24+6R-speed designs.

Picture links:

lego 12-speed tractor ver6.ldr

Ratios 24-speed

24-speed tractor pic1

24-speed tractor pic2

Picture links:

Picture links:

LDraw files:

lego 24-speed tractor remake.ldr

Brickshelf Gallery:

12and24spdTractor

YouTube videos:

12-speed tractor orig pic1

This lego 12+4R-speed version II (12-speed tractor version VI) is new design in which ratios are close to John Deere 9400’s transmission. 24+8R-speed lego transmission is remake and now equipped with lego powershift. Old lego 24+8R-speed has only splitter instead of powershift and its ratios are based on different John Deere model that doesn’t have powershift as optional equipment. So old lego design is moved to page Junkyard if you want to check it.

These transmissions are used so that range A is for lower field working speeds, ranges B and C are for higher field working speeds and range D is for transportation. Other ranges don’t overlap but ranges B and C overlap so heavily that they actually work like mechanical splitter: you get progressive speeds by gear order A1-A2-A3-B1-C1-B2-C2-B3-C3-D1-D2-D3. This gear order with halved gear steps helps to choose right speed for the most working situations but it’s too difficult to use in upshifting procedure.

Additional powershift allows small speed changes by button shifts under heavy driving resistance without cutting torque in drive line. Idea is to move off in powershift stage low and drive in stage high. More info about real powershift is in chapter S.1. 8+4R-speed & 16+8R-speed. Lego powershift is done by two identical motors and a planetary gear (2-speed setup of C.7. 3-speed powershift for tractor version II on page Planetary gears). It works so that you get stage low by running forward only motor 2 (M2) while motor 1 (M1) is stopped. In stage high both motors are run forward. This lego transmission has reverse gears but you get both powershift stages also when you run motors in reverse.

John Deere 9400 is a real monster tractor that has 4WD, large tyres and articulated steering. So in lego design my idea is that lego motor and additional powershift are located in tractor’s engine bay. Main gearbox is in cabin and after it there is a universal joint for articulated steering. Finally there is range unit located between rear tyres. It’s not modeled but then you can add enough speed reduction before differentials and another universal joint to get front wheel drive. For suspension front axle is supposed to be pendular design. There is also simple example for lego articulated steering: 40 teeth gear wheel is in the middle of the turning point and it’s connected rigid to rear frame. Steering wheel axle with 8 teeth gear is located to front frame.

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T. Tractor Transmissions Part II:

Here is tractor transmissions part II. For universal tractor info check beginning of the previous section S. Tractor Transmissions Part I.

T.1. 12+3R-speed, overall gear ratio 39,68:

Original setup: 4-speed main gearbox + 3-speed range
Alternative setups I & II: 3-speed range + 4-speed main gearbox
Inspirer: Lamborghini Rekord 75 (TractorData)

12-speed Tractor Transmission Version VII

12-speed Tractor Transmission Version VII Alter I

12-speed Tractor Transmission Version VII Alter II

“If anyone of you have 12 gears in your Lamborghini raise your hand. So, you are Italian farmers, right?” Lamborghini Rekord is not a super car, it’s a small tractor. :-) Its transmission contains 12 forward and 3 reverse gears and it’s done by 4-speed main gearbox with reverse gear and 3-speed range unit with ranges low (L), medium (M) and high (H).

Picture links:

12-speed tractor orig pic2

12-speed tractor orig pic3

12-speed tractor orig pic4

12-speed tractor orig pic5

12-speed tractor orig pic6

Picture links:

12-speed tractor alter1 pic1

12-speed tractor alter1 pic2

12-speed tractor alter1 pic3

12-speed tractor alter1 pic4

12-speed tractor alter1 pic5

Picture links:

12-speed tractor alter2 pic1

12-speed tractor alter2 pic2

12-speed tractor alter2 pic3

12-speed tractor alter2 pic4

12-speed tractor alter2 pic5

Picture links:

LDraw files:

lego 12-speed tractor ver7.ldr

lego 12-speed tractor ver7 alter.ldr

lego 12-speed tractor ver7 alter2.ldr

Brickshelf Gallery:

12spdTractor7

YouTube videos:

Building example orig & alter I

Building example alter II

Available is three lego setups. In original setup main gearbox is before range unit but in alternative setups they are located vice versa. Idea in alternative setups is that you hide seldom used range unit into tractor’s engine bay with lego motor and locate more used main gearbox into cabin. In alternative setup I you get lego motor centered if you use Mu(20)-Mu(20) or S(16)-M(24) gear pair as pre ratio (move 1,5 studs right and 2 studs down from motor to range input).

Alternative setup II is upgraded version of alter I with two changes: 4th main gear uses new 20 teeth double bevel clutch gear and reverse gear’s XS(8)-XS(8)-XS(8) gear train is replaced with XS(8)-S(16)-XS(8) due to relocation. These improvements give simpler and two studs shorter design so this alternative setup II recommended setup for lego builders. And you get lego motor centered by adding XS(8)-XS(8) gear pair between motor and input axle under front Su(12)-Mu(20) gear pair.

You may notice in lego design that main gearbox is not the simplest structure and its gear steps are not geometrical. Ratios are chosen so that gear steps are close to Rekord’s ones. Despite the complexity this lego transmission is still quite compact design. While gear steps are quite large and ranges overlap only a little this transmission has large overall gear ratio. So you can call the lowest range as creeper range. And like in typical tractor transmissions ratio of the reverse gear is near to ratio of 2nd forward gear. Check picture Speed comparison.

And as unnecessary note if you want to build Lamborghini Crono tractor you can check later chapter T.7. 15+15R-speed.

T.2. 6+2R-speed version II, overall gear ratio 12,00:

Main gearbox + range
Inspirer: Ford 3600 (TractorData)

This 6+2R-speed version II is tractor transmission inspired by old Ford 3600. It has 3-speed main gearbox with reverse gear together with range unit. Design seems to be quite basic but we need to take a closer look.

Picture links:

LDraw files:

lego 6-speed tractor ver2.ldr

Brickshelf Gallery:

6spdTractor2

YouTube videos:

Gear steps in main gearbox are large which means that you can start in high range for transportation even when need to move off on difficult terrain. But the greatest idea in this transmission is swapped 3rd and 4th gear in shift pattern. This swap creates smaller gear steps in middle gears to help working speed control. So there are as much as four gears of six that suit to field working speeds 4-12 km/h. 1st gear is for low speed operation and 6th gear for transportation. All in all this is quite versatile transmission for farm tractor despite the fact that it has only six forward gears.

You can notice that lego design is not the simplest and smallest. Reason for complex design is that ratios and shift pattern are copied from real Ford’s transmission. For simpler design check earlier basic 6+2R-speed version I (inspired by old Massey Ferguson 150) or later 6+2R-speed version III (inspired by old Valmet 602).

It needs some attention to get simple shift levers for both main gearbox and range unit. One example is available in YouTube clip Building example.

T.3. 12+4R-speed version III, overall gear ratio 20,00:

Main gearbox + range
Inspirer: Ford 4430 (TractorData)

12+4R-speed Tractor Transmission Version III

This 12+4R-speed version III (12-speed tractor version VIII) is not a cousin of earlier 12+4R-speed designs but big brother of 8+4R-speed transmission. It contains 4-speed main gearbox and 4-speed range unit with ranges high (H), medium (M), low (L) and reverse (R). So now there is reverse range with four main gears, not one reverse gear in four ranges. Reverse range is about as fast as medium range.

Picture links:

12-speed tractor pic6 (no bricks)

12-speed tractor pic7 (no bricks)

LDraw files:

lego 12-speed tractor ver8.ldr

Brickshelf Gallery:

12spdTractor8

YouTube videos:

lego 6-speed tractor ver3.ldr

Ratios of lego transmission follow quite accurately Ford’s transmission. Main steps vary quite a lot so that steps 1-2 and 3-4 are 1,60 but step 2-3 is only 1,25. This design sounds weird but there is clever logic behind it. Those larger steps ensure that speed range in reverse is high enough. They also help to move off in high range while gear H1 is slower. But clever idea is in overlapping ranges: for example gear M1 fits right between gears L3 and L4. When you sort gears by ratios you can see there are good small gear steps in middle gears through whole speed range, only steps L1-L2 and H3-H4 are larger. This gives good selection of gears for working speed control. Check table Ratios sorted in picture Ratios. This transmission uses same idea of overlapping ranges as John Deere’s 16+16R-speed transmission.

All in all lego design is narrow and not very long for being an inline setup. One possible issue can be efficiency problems in some gears. 4th gear in main gearbox is overdrive in which used gear pair S(16)-XS(8) can be problematic. And in range unit low and reverse range has ratio 2,50 after synchro parts which means fast spinning clutch gears S’(16C) when higher ranges are used. So, if this transmission doesn’t fail efficiency test drive it’s quite good choice for lego builders.

This lego transmission is inspired by Ford 4430 but same tractor has also been sold as New Holland and Fiat.

T.4. 6+2R-speed version III, overall gear ratio 8,33:

Main gearbox + range
Inspirer: Valmet 602 (TractorData)

6-speed Tractor Transmission Version III

This 6+2R-speed version III is another simple and compact tractor transmission, this time inspired by old Valmet 602. Design has again 3-speed main gearbox with reverse gear plus range unit. Main gearbox and range unit are parallel, and two transmission driving rings on the left belong to main gearbox and last one on the right to range unit. My goal was to design realistic lego transmission including real shift pattern and ratio set but it turned out to be very small and simple lego design as well.

Picture links:

LDraw files:

Brickshelf Gallery:

6spdTractor3

Google Pictures

YouTube videos:

18-speed tractor pic1 (shift patterns)

Like in 6+2R-speed version II we need to notice that 3rd and 4th gear are swapped in shift pattern. There are two reasons for that. First advantage is slower starting gear in high range so you can start transportation even on rougher terrain without need for range change. But major reason for this swap is smaller gear steps in middle gears so you can squeeze as much as four gears suitable for field working speeds 4-12 km/h. So 1st gear is for low speeds, gears 2-5 for major working speeds and 6th gear for transportation.

So, if you fancy simple and compact lego transmission for old tractor this one is very realistic design to use for.

T.5. 18+6R-speed & 24+6R-speed, overall gear ratios 13,89 & 55,56:

18+6R-speed: 3+R-speed auxiliary + 6-speed main gearbox
24+6R-speed: 4+R-speed auxiliary + 6-speed main gearbox
Inspirer: Deutz-Fahr DX 86

18-speed Tractor Transmission Version II

24-speed Tractor Transmission Version II Remake

These 18+6R-speed and 24+6R-speed tractor transmissions are inspired by Deutz-Fahr DX 86 but design is related to basic 8+4R-speed which contains 4 main gears plus ranges high, low and reverse. Now we have more gears in both auxiliary and main gearbox: 18+6R-speed has 6-speed main gearbox with ranges high (H), medium (M), low (L) & reverse (R). 24+6R-speed is otherwise same design but it has additional creeper (LL) range.

Picture links:

Ratios 18-speed

18-speed tractor pic2

18-speed tractor pic3

18-speed tractor pic4

18-speed tractor pic5

Picture links:

Ratios 24-speed

24-speed tractor pic1 (shift patterns)

24-speed tractor pic2

24-speed tractor pic3

24-speed tractor pic4

24-speed tractor pic5

24-speed tractor pic6 (no bricks)

LDraw files:

lego 18-speed tractor ver2.ldr

lego 24-speed tractor ver2 rm.ldr

Brickshelf Gallery:

18and24spdTractor

YouTube videos:

Building example 18- & 24-speed

18+6R-speed is new design but 24+6R-speed is remake with several improvements. Remade 24+6R-speed has smaller design, better ratio set and accurate shift pattern in auxiliary without possible efficiency problems made by large overdrive situations in some gears. Auxiliary’s shift pattern is really confusing but it’s copied from real Deutz-Fahr’s transmission. Earlier setups are still available on page Junkyard if you want to check them.

In 18+6R-speed design lego motor and auxiliary can be located into 6 studs wide engine bay while 8 studs wide main gearbox is designed to locate inside cabin. 24+6R-speed design needs 8 studs wide engine bay in your lego tractor if only main gearbox fits inside cabin. In 24+6R-speed creeper range adds fifth position in shift pattern and needs many gear pairs in bottom layer due to high ratio so auxiliary needs more space than in 18+6R-speed. So if you can fit only 6 studs wide auxiliary into lego tractor’s engine bay your choice is basic 18+6R-speed but otherwise I recommend to use 24+6R-speed with all its goodies.

These transmission setups concentrate on forward gears: After low range’s top gear (L6) you could shift direct to high range’s 1st gear (H1) but overlapping medium range gives versatility in driving in many different ways. For example you need less compound auxiliary and main gearbox shifts and there are more gears for field working speeds (4-12 km/h). And in front loader working you can choose suitable main gear and then use only auxiliary: for about same speed in both directions you shift between medium and reverse range and for slower forward speed than reverse speed you can shift between ranges low and reverse. But reverse gears are weak point in these transmission setups. Reverse range is slightly slower than medium range so there are only middle speed reverse gears. Lack of fast reverse gears is not a problem but especially in 24+6R-speed only creeping speed direction is forward. Usually creeper speeds are only needed in forward but lack of creeper speeds in reverse can be problem in this transmission. If you want creeper speeds also in reverse in your lego tractor I recommend to check below 15+15R-speed (basic 5x3), 30+15R-speed (forward gears splitted) and 45+45R-speed (3-speed powershift) tractor transmissions.

T.6. 30+15R-speed, overall gear ratio 126,00:

5-speed main gearbox + 3-speed range + 2+R-speed split/reverse
Inspirer: Deutz-Fahr Agroplus

This tractor transmission has 5-speed main gearbox, 3-speed range unit and 2+R-speed split/reverse auxiliary. So in this transmission reverse gear is combined with splitter, not with range unit like in earlier introduced 2+R-speed auxiliaries. Altogether you have 30 forward and 15 reverse gears in this transmission so in forward number of gears is doubled and gear steps are halved compared to reverse.

Picture links:

30-speed tractor pic7 (range shifter locking)

30-speed tractor pic1

30-speed tractor pic2

30-speed tractor pic3

30-speed tractor pic4

30-speed tractor pic5

30-speed tractor pic6

LDraw files:

lego 30-speed tractor remake.ldr

Brickshelf Gallery:

30spdTractorRemake

YouTube videos:

Available is now remake with much more compact design and simpler reverse gear. In original design sliding axle range unit adds too much length and width for easy lego tractor use. With some testing I found a way to relocate range unit so front part has only main gearbox’s width and parallel located range unit and split/reverse are not much wider. If you want to check original design it’s located on page Junkyard.

Idea in this transmission is that you can split forward gears to get more accurate working speed control but in upshifting procedure splitting is not useful while you will need also difficult two stick shifts. So in upshifting you start with low split, shift first only main gearbox and as last upshift shift to high split. In reverse you have only main gear steps but 15 reverse gears cover the whole speed range so you have also fast reverse gears. Range unit have not only low and high range but also creeper range and ranges don’t overlap which makes overall gear ratio very large and allows also very low speed driving. All in all this is pure mechanical tractor transmission which gives maximum number of gears without overlapping ratios.

This transmission gives 45 different gears but you can still have more gears so check big brother of this transmission, later shown 45+45R-speed version II with 3-speed powershift.

T.7. 15+15R-speed, overall gear ratio 120,00:

5-speed main gearbox + 3-speed range + shuttle
Inspirer: Lamborghini Crono 75

This 15+15R-speed is quite basic tractor transmission with very large overall gear ratio. It contains 5-speed main gearbox, 3-speed range unit and shuttle (fwd/rev). This transmission is inspired by small Lamborghini Crono tractor but it’s also cousin of Deutz-Fahr’s basic 10+10R-speed (no creeper range), 30+15R-speed (splitted forward gears) and 45+45R-speed (3-speed powershift) transmissions.

Picture links:

lego 15-speed tractor.ldr

15-speed tractor pic1

15-speed tractor pic2

15-speed tractor pic3

15-speed tractor pic4

15-speed tractor pic5

LDraw files:

Brickshelf Gallery:

15spdTractor

YouTube videos:

This 15+15R-speed replaces outdated 45+45R-speed version I (3x5x3, range + main gearbox + splitter), which is moved to page Junkyard if you want to check it. Old 45+45R-speed has 3-speed splitter representing powershift but I already have lego powershift designs available. In 15+15R-speed splitter is removed but redesigned construction is also more compact than 45+45R-speed without splitter.

While there is three transmission driving rings and clutch gears in a row in power flow this lego transmission has potential backlash problem, which means bad response when changing driving direction especially in low range gears.

This 15+15R-speed lego transmission is quite compact but it requires 8 stud wide engine bay in your lego tractor. If that is acceptable this one is good choice for both small Lamborghini Crono and as universal tractor transmission with large overall gear ratio. If you fancy awful lot of gears for your lego tractor there are several transmissions available: With 3-speed powershift you can choose later shown Deutz-Fahr inspired 45+45R-speed version II or Valtra inspired 36+36R-speed. For pure mechanical designs you can check earlier Deutz-Fahr inspired 24+6R-speed and 30+15R-speed.

T.8. 45+45R-speed version II, overall gear ratio 150,00:

3-speed powershift + 5-speed main gearbox + 3-speed range
Inspirer: Deutz-Fahr Agroplus

Here is upgraded version of lego 45+45R-speed tractor transmission. This version II has true 3-speed lego powershift (Low, Medium and High), 5-speed main gearbox and 3-speed range unit (creeper LL, low L and high H).

Picture links:

Enforced planetary gear pic1

45-speed tractor pic1

45-speed tractor pic2

45-speed tractor pic3

45-speed tractor pic4

45-speed tractor pic5

Picture links:

Enforced planetary gear pic2

LDraw files:

lego 45-speed tractor ver2.ldr

Brickshelf Gallery:

45spdtractor2

YouTube videos:

Lego powershift is done by two motors and a planetary gear. For simple use you need extra forward-stop-reverse switch (pole reverser) and picture Wiring shows how to wire this switch, battery box and two motors together. Using this powershift unit is easy: you choose driving direction with battery box’s switches and powershift’s stage with that forward-stop-reverse switch (picture Battery box). For more information about this powershift you can check original C.7. 3-speed powershift for tractor version II in Planetary gears. Building tip: Leave small gap between planet carrier’s axle joiner and first gear wheel of main gearbox’s input axle. It’s possible while 8 teeth gear of motor 1 goes a little bit inside planet carrier. This is to prevent possible collision problems between planet carrier and idler gear of motor 2.

So this powershift allows you to shift your lego tractor remotely while moving and under load. Although powershift covers only small speed range 5 main gears with 3 ranges give very large speed range where you can use these powershift’s small speed changes. In typical use you first choose desired speed range with main gearbox and range unit. (In real tractor you will need also main gearbox shifting when driving in high range.) When you move off powershift is in low and then you add more speed by shifting remotely powershift to medium and high. If driving resistance gets too high or you need to slow down a little you can downshift with powershift.

So, all in all this transmission gives awful lot of gears with partial powershift and very large overall gear ratio. If you have two identical motors and forward-stop-reverse switch and you are going to build large lego tractor this transmission is one choice for you. To get more powershift gears with legos you will need 3 motors and 2 planetary gears like in later shown 30+30R-speed with 5-speed powershift.

T.9. 36+36R-speed, overall gear ratio 57,14:

3-speed powershift + 4-speed main gearbox + 3-speed range
Inspirer: Valtra T121 Classic

36-speed Tractor Transmission Alternative Setup

This 36+36R-speed transmission is inspired by Valtra and it has 3-speed powershift (Low, Medium and High), 4-speed main gearbox and 3-speed range unit (creeper LL, low L and high H). Lego design is close to previous 45+45R-speed version II but only 4 main gears makes design more compact. Available is long and narrow original setup and shorter alternative setup with parallel located main gearbox and range unit.

Picture links:

36-speed tractor pic1

36-speed tractor pic2

36-speed tractor pic3

36-speed tractor pic4

36-speed tractor pic5

Picture links:

36-speed tractor alter pic1

36-speed tractor alter pic2

36-speed tractor alter pic3

36-speed tractor alter pic4

36-speed tractor alter pic5

Picture links:

LDraw files:

lego 36-speed tractor.ldr

lego 36-speed tractor alter.ldr

Brickshelf Gallery:

36spdtractor

YouTube videos:

Basic use is that you first choose desired ratio with main gearbox and range unit to be used with powershift stage high. But you move off with powershift in low and then add speed with stages medium and high, remote shift design allows you to do this during driving. So, if driving resistance gets too high or you need to slow down you can simply downshift with powershift. Main gearbox and range unit allow very large speed range where these small step powershifts can be done.

Again lego powershift is done by two identical motors and a planetary gear. For simple use you need extra forward-stop-reverse switch (pole reverser) and picture Wiring shows how to wire this switch, battery box and two motors together. Using this powershift unit is easy: you choose driving direction with battery box’s switches and powershift’s stage with that forward-stop-reverse switch (picture Battery box). For more information about this powershift you can check original C.7. 3-speed powershift for tractor version II in Planetary gears. For example there you can find enforced planetary gear for low speed motors. Building tip: Leave small gap between planet carrier’s axle joiner and first gear wheel of main gearbox’s input axle. It’s possible while 8 teeth gear of motor 1 goes a little bit inside planet carrier. This is to prevent possible collision problems between planet carrier and idler gear of motor 2.

So, if you can build this powershift design, here is two quite compact and useful setups to build. Depending on your tractor design you can choose narrow inline design or short parallel design.

T.10. 30+30R-speed, overall gear ratio 79,20:

5-speed powershift + 6-speed range
Inspirer: Valtra N104 HiTech

30-speed Tractor Transmission Version II

This lego 30+30R-speed tractor transmission has 5-speed powershift and 6-speed range unit (ranges LA, LB, A, B, C and D). 5-speed powershift contains 3 identical motors and 2 planetary gear version III:s and is introduced in C.8. 5-speed powershift for tractor on page Planetary gears. So visit there for more info about this 5-speed powershift remake. You need a battery box and two forward-stop-reverse switches (pole reversers) to operate this system. Check pictures Ratios and Control unit.

Picture links:

Powershift pic1 (planetary gears)

30-speed tractor pic1

30-speed tractor pic2

30-speed tractor pic3

30-speed tractor pic4

30-speed tractor pic5

30-speed tractor pic6

Picture links:

Data sheet powershift

Powershift pic2 (planetary gears)

Powershift pic3 (no bricks)

Control unit pic1

Control unit pic2

LDraw files:

lego 30-speed tractor ver2.ldr

Brickshelf Gallery:

30spdTractor2

YouTube videos: