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Ari Holopainen / gearbox12 | |
| D. Gearboxes With 2-speed Motor:
This Electric RC Race Buggy Motor has two outputs with gear step 23/17=1,35. If you have it you can take advantage of these outputs and use them both in one transmission. When used in splitter this gear step suits to 10-speed truck transmission. In main gearbox motor can be used so that two top gears use motor’s high output and lower gears low output. So, motor’s step 1,35 as second highest gear step gives several transmission possibilities: 10-speed with range-change unit for truck, 4-speed for muscle car, 5-speed for personal car, 6-speed for van and 7-speed for coach. D.1. 10-speed with splitter for truck, overall gear ratio 10,15: Splitter + main gearbox, also 12-speed conversion Inspirer: Scania GS771
This one is 10-speed transmission for mid range truck and 2-speed motor is used as splitter unit. Notable thing is that 8th and 9th gear are swapped in shift pattern. This swap gives halved gear steps in shifts 7-8, 8-9 and 9-10 and better performance in high speed driving. But swap also reduces overall gear ratio so this transmission doesn’t suit to heavy duty trucks.
This transmission is sister of M. 10-speed Transmission on main page. So if you don’t have this motor you can use this main gearbox directly with splitter unit of those transmissions on main page. It makes small changes in ratios and gear steps but not too much. On the other hand main gearboxes of those main page transmissions can be used with this motor-splitter. While this transmission is inspired by 10-speed Scania transmission I wanted 10 gears in lego transmission too. If you need more gears and larger overall gear ratio this transmission is easy convert into 12-speed version: just flip around 16 teeth clutch gear on the left synchro axle. Next pictures give you more info.
D.2. 10-speed version II B for truck, overall gear ratio 15,03: Main gearbox + range-change unit Inspirer: Eaton Fuller Advantage Series FA-10B
This one is 10-speed transmission for linehaul truck with 5-speed main gearbox and range-change unit. 2-speed motor used so that main gears 4-5 are from motor’s high output and gears 1-3 and reverse from low output. Main gearbox and range-change unit are parallel which gives quite short design so only space issue is width. This parallel design means also that there is a short cut in power flow in gears 8th and 9th between main gearbox’s and range-change unit’s clutch gears.
This lego transmission is only possible with studless frame due to used Su(12)-S(16) gear pairs. So there is exceptional 1,75 stud axle base in this transmission and it needs some careful axle locating if you build this version. Bushes should show to you where those special 0,25 stud gaps are needed. And reverse gear’s idler gear is slightly difficult to support in studless frame. Lego structure can be difficult to figure out from pictures so I recommend to download LDraw file or check YouTube clip Built it. One notable thing is gear order in shift pattern while main gearbox’s 4th and 5th gear are swapped. This swap gives easier use for motor’s gear step 1,35 but idea is taken from real Eaton’s transmissions: older 10-speed overdrive Fullers (RTO series) have same kind of swap. But these older 10-speed Fullers have smaller gear steps and overall gear ratio than this lego design and they are not suitable to model with this 2-speed lego motor. Lego version’s overdrive ratio set is close to newer Eaton Fuller Advantage Series FA-10B which is direct drive. Although ratios are all different gear steps and overall gear ratio are quite close to each other including larger range step 4-5. Reverse gear is also slower than 1st gear in main gearbox but lego version’s step -1,25 is a little bit larger than Fuller’s -1,18. Check similarities from picture Ratio comparison. But, there is a little reality issue while lego version’s shift pattern and ratio set are from different 10-speed Fuller models, but we can accept this small exception, can’t we. :-) More info about swapped gears in shift pattern is in chapter N.5. More about twin stick transmissions on main page. There is also sister design of this lego transmission with slightly different ratio set, check chapter I.5. 10-speed version V on main page. All in all this lego transmission is pretty realistic design for American linehaul semitrailer truck. Lego using idea goes so that you put motor and transmission partly under cabin but leave shift levers usable behind cabin. Then you put rear axles and fifth wheel rear enough so that semitrailer doesn’t hide shift levers. So there is still room for 6-cylinder inline engine in truck’s engine bay. D.3. 4-speed version B for muscle car, overall gear ratio 2,82: Inspirer: Borg Warner Super T-10 (X ratio) (Richmond Gear, present manufacturer) Progressive gear steps
This one is quite simple and compact 4-speed transmission for old American muscle cars and other sport cars. It’s inspired by X ratio set of Borg Warner Super T-10. 2-speed motor is used so that gears 3-4 uses motor’s high output and gears 1-2 low output so motor’s step 1,35 is between 2nd and 3rd gear.
All in all this gearbox has quite good progressive gear steps and overall gear ratio is typical for close ratio 4-speed sport cars. Progressive gear steps mean the higher gear the smaller gear step between gears. Note that progression in lego transmission is not optimized because it follows Borg Warner’s ratios and gear steps. If you want faster 1st gear (smaller gear step 1-2) you can do simple conversion: change rear 12 teeth double bevel gear to two 14 teeth thin bevel gears. And if you need ratios, gear steps and overall gear ratio of that conversion you can make request so I can calculate changed values with Excel. :-) Design has studless frame mainly because of studless motor but also brick frame is possible altough I haven’t modelled it. If you don’t have this 2-speed motor there is an ordinary sister transmission for this design, check original setup (X ratio) in chapter P.9. 4-speed version IV on main page. D.4. 5-speed version B for personal car, overall gear ratio 4,06: Progressive gear steps
Another use for this 2-speed motor is overdrive 5-speed personal car transmission. Gears 4-5 use motor’s high output and gears 1-3 low output. When 5th gear is overdrive and 4th gear direct motor’s gear step 1,35 can be used between gears 3 and 4. All in all this gearbox has very good progressive gear steps and overall gear ratio is typical for 5-speed personal car transmissions. H shift pattern is typical for light trucks and some sport cars but it’s easier to get progressive gear steps in lego gearbox with this arrangement. Progressive gear steps mean the higher gear the smaller gear step between gears.
Design has studless frame mainly because of studless motor but also brick frame is possible altough I haven’t modelled it. D.5. 6-speed version B for van, overall gear ratio 6,96: Inspirer: ZF Ecolite for van Progressive gear steps
In this 6-speed transmission overall gear ratio is too small for light trucks but too high for typical personal cars so transmission suits best for vans. Other possible use is wide ratio personal car transmission which are normally used in diesel powered cars.
In lego version gears 5-6 use motor’s high output and gears 1-4 low output. Motor’s gear step 1,35 is used in gear pair 4-5 while 5th gear is direct and 6th gear overdrive. Like in real 6-speed transmissions also this version has progressive gear steps which means the higher gear the smaller gear step between gears. This design is only possible with studless frame while there is horizontally located Mu(20)-S(16) gear pair in 2nd gear. This gear pair has unusual 2,25 stud axle base so put axle carefully into right place if you build this transmission. D.6. (reserved for 7-speed version B for coach) This is for 7-speed rear engine transmission for coach inspired by Eaton Fuller... E. Flat Gearbox Designs: Here are some flat transmissions where axles are in one or 1,5 layers. 1,5 layers mean that there is small vertical movement together with horizontal movement, but too small to put axles vertical. Designs are transversal and long but narrow so truck transmissions can be placed partly inside truck’s frame under cargo body. Shift levers are on the left side of the truck outside the frame. Also their height is minimized so it’s possible that they fit under cargo body too. In tractor use you can think that lego motor and front part of transmission is in tractor’s narrow engine bay and the rest under cabin. Here is how to make basic 8-speed transmission for mid range truck, small step 16-speed for linehaul truck and 14-speed for heavy duty truck. For tractor use here is basic 8+8R-speed and basic 8+4R-speed, that has two enlargements: 16+8R-speed with mechanical splitter and 12+8R-speed with creeper unit. E.1. Basic 8-speed for mid range truck, overall gear ratio 11,43: Range + main gearbox
This 8-speed transmission is basic design with 4-speed main gearbox and range-change unit. Instead of real 8-speed trucks gear steps are pure geometrical. Real 8-speed transmissions have normally smaller gear step 7-8 (also step 3-4 due to range-change unit) to get better performance in high speed driving. This is why this lego transmission doesn’t have inspirer. Lego transmission has large front ratio (6,00) from motor to range-change unit so this transmission suits to high speed motor. Shift lever in main gearbox allows only 4 positions so this transmission doesn’t have reverse gears.
This transmission is easy to enlarge to 16-speed version by adding splitter unit. Then you get small gear step transmission for linehaul truck. Or you can use 2 crown gears on 1st axle to get sliding axle driving direction changer so you will get 8+8R-speed tractor transmission. E.2. Small step 16-speed for linehaul truck, overall gear ratio 13,71: Splitter + range + main gearbox Inspirer: Volvo SR62
This 16-speed transmission has same type 4-speed main gearbox and range-change unit as previous 8-speeder. New feature is splitter unit which halves the gear steps and doubles the number of gears. Overall gear ratio is not very large so transmission suits to linehaul truck. While there is front ratio 3,00 and underdrive splitter this transmission works best with high speed motor. There are no reverse gears in this transmission so gears are: 1L-1H-2L-2H-3L-3H-4L-4H-5L-5H-6L-6H-7L-7H-8L-8H.
Best known real 16-speed transmission is ZF Ecosplit but it has larger overall gear ratio than this lego version. Now basic lego design lead to smaller overall gear ratio, so it and gear steps are closer to Volvo’s SR62 transmission. This is sister transmission of K.2. 16-speed transmission version II on main page. For lego heavy duty trucks I have 14-speed transmission which has larger gear steps and overall gear ratio. E.3. 14-speed for heavy duty truck, overall gear ratio 31,25: Range + splitter + main gearbox Inspirer: Volvo and Scania
This 14-speed transmission has 3-speed main gearbox including also crawler gear (C) together with splitter and range-change unit (2x3x2+2). Transmission has larger gear steps than previous 16-speeder so overall gear ratio is large and suitable for heavy and severe duty trucks. There is some progression in gear steps so step between highest gears is not so large as in transmission with geometrical gear steps. There are no reverse gears in this transmission so gears are: CL-CH-1L-1H-2L-2H-3L-3H-4L-4H-5L-5H-6L-6H.
This design is sister transmission of 14-speed versions I & II on main page. E.4. Basic 8+8R-speed for tractor, overall gear ratio 11,43: Fwd/rev + range + main gearbox Inspirer: Massey Ferguson 4220
This lego 8+8R-speed transmission is tractor version of earlier shown basic 8-speed truck transmission. Now there are two crown gears right next motor to get driving direction changer. Main gearbox is taken directly from that 8-speed but 16-speeder’s range-change unit suited better to this tractor design. Driving direction changer has ratio 2,00 so this design suits best to high speed motor.
E.5. Basic 8+4R-speed for tractor, overall gear ratio 11,43: Range/reverse + main gearbox Inspirer: Ford 6610 Dual-range
This 8+4R-speed transmission has same main gearbox as previous 8+8R-speed tractor and earlier basic 8-speed truck transmission. Now auxiliary has ranges low, high and reverse, so you have 4 slow and 4 fast gears in forward and 4 slow gears in reverse. This is direct drive version so it suits also to low speed motors. Unlike previous transmissions this one needs 1,5 layers.
This transmission is cousin of S.1. 8+4R-speed tractor transmission on main page with slightly different ratios in auxiliary. E.6. 16+8R-speed with splitter for tractor, overall gear ratio 13,71: Splitter + range/reverse + main gearbox Inspirer: Valmet 900
This 16+8R-speed transmission is enlarged version of previous 8+4R-speed tractor transmission. It contains same 4-speed main gearbox and range unit that has ranges high, low and reverse. New feature is mechanical splitter to enable more accurate working speed control. So this lego design is also close to earlier 16-speed truck transmission. This time lego design is overdrive so it suits best to low speed motor. Like 8+4R-speeder this transmission requires 1,5 layers.
When you look closely you can notice that this 16+8R-speed version has different inspirer than earlier 8+4R-speed version. This oddity comes from the fact that Ford offered only 2-speed powershift to enlarge 8+4R-speeder to 16+8R-speed version. On the other hand also Valmet had 8+4R-speed transmission and they offered mechanical splitter or creeper unit as optional equipment giving 16+8R-speed or 12+8R-speed versions. So this lego version follows that 16+8R-speed splitter version. This one has also cousin in S.3. 16+8R & 12+8R-speed tractor transmissions on main page with slightly different ratios in range unit. E.7. 12+8R-speed with creeper for tractor, overall gear ratio 45,71: Creeper + range/reverse + main gearbox Inspirer: Valmet 900
This 12+8R-speed transmission is another enlargement of earlier 8+4R-speed tractor transmission. So it’s based on 4-speed main gearbox and range unit with ranges high, low and reverse. Now additional equipment is creeper unit which can be switched on with ranges low and reverse. So it offers 4 extra slow gears in both driving directions giving 12 forward and 8 reverse gears altogether. This is direct drive version so it suits also to low speed motors and like 8+4R-speeder this transmission requires 1,5 layers.
If previous 16+8R-speed gives smaller gear steps this 12+8R-speed enables extra slow speeds. This one has also cousin in S.3. 16+8R & 12+8R-speed tractor transmissions on main page with slightly different ratios in range unit. F. Race Transmissions: Here are located transmissions that are designed for racing use. First three are drag race transmissions that have special lightning rod shifters to minimize shifting errors under maximum acceleration. Fourth one is 4-speed manual transmission for NASCAR racing with extremely close ratio design. F.1. 4-speed drag race version I, overall gear ratio 3,33: Inspirer: Lightning rod shifter
This design is 4-speed manual drag race transmission and it’s equipped with lightning rod shifter.
Lightning rod shifter means that you have three forward-rearward shift levers for three upshifts. Left one is for shift 1-2, middle one for shift 2-3 and right one for shift 3-4. You start with levers in front position and upshift by pulling levers rearward one at time starting from left lever. Check picture Shifting procedure. So it’s like three 2-speed gearboxes in a row. Idea is to minimize shifting errors under pressure in drag racing while shift levers have only two positions. Downshift happens in reversed order: while all levers are in rear position you downshift by pushing levers forward starting from right lever. I’m not drag race transmission specialist so I don’t know their typical gear steps and progression stage. Ratios of this lego version are taken from GM 4L80E 4-speed conventional automatic transmission which can be equipped with lightning rod shifter. One note is that GM 4L80E is overdrive transmission while lego version is direct drive but gear steps and overall gear ratio are close to each other. F.2. 4-speed drag race version II, overall gear ratio 2,86: Inspirer: Lightning rod shifter
This version II is another 4-speed manual drag race transmission with lightning rod shifter. This design has same gear step 3-4 as earlier version I but less progression so it reduces lower gear steps and overall gear ratio.
Check previous version I or picture Shifting procedure for how to operate lightning rod shifter. In this lego version ratios are taken from Borg Warner ST10 (CC Ratio) 4-speed manual transmission. F.3. 3-speed drag race, overall gear ratio 2,50: Inspirer: Lightning rod shifter
This one is compact 3-speed version of drag race transmissions that has lightning rod shifter.
Lego design is actually 4-speed version I without 4th gear and its smallest gear step. So you have only two shift levers: left one for shift 1-2 and right one for shift 2-3. You start with both levers in front position and upshift by pulling first left lever and then right lever rearward. Downshift happens reversed: first you push forward right lever and then left lever. This time lego ratios are taken from GM TH350 3-speed conventional automatic transmission which can be equipped with lightning rod shifter. F.4. 4-speed NASCAR, overall gear ratio 1,79:
If I understand it right older rules of NASCAR say that you have to use 3-4-speed manual H shift pattern transmission with next ratio limits: 1st gear ratio must be 1,70 or higher, 3rd gear ratio (2nd in 3-speed version) must be 1,14 or higher and top gear must have direct ratio. Other notable thing is that racing happens in high speeds on oval shaped tracks. So you don’t need fast acceleration in lower speeds which means that NASCAR transmissions are extremely close ratio versions. So overall gear ratio and gear steps are usually too small for normal 4-speed transmission, even for close ratio sport car.
Google search gave as real example ratios 1st 1,80, 2nd 1,45, 3rd 1,16 and 4th 1,00. These ratios are quite close to NASCAR’s ratio limits so it’s likely that also wider ratio sets are used. With legos I almost managed to copy these ratios including progressive gear steps: 1st 1,79, 2nd 1,43, 3rd 1,17 and 4th 1,00. Available is two lego setups with identical ratio set: original setup is shorter but wider while alternative setup is more narrow but longer. Lego setups differ only how 1st gear is arranged. So depending on your lego NASCAR design you have two setups which to choose more suitable. For other use than NASCAR these lego transmissions are useless due to too small overall gear ratio. This is also why these lego transmissions are here in race transmissions, not in section P. Personal Car Transmissions on main page.
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