LUGNET News : ~3813/notes


Ari Holopainen / notes

Quick Links:

[Differentials]: self-made differentials with different torque allocations, introduction to torque allocation calculations
[Planetary gears]: different kind of planetary gears with theories, planetary gear sets, gearboxes from differentials, high ratio planetary gears, freewheel clutch
[Basic & special designs]: some auxiliaries and main gearboxes, transfer cases, gearboxes from 2-speed motor, flat designs and race transmissions
[Useful stuff]: some shift lever ideas for both sliding axle and H shift pattern designs
[Vehicles]: some of my past and present lego vehicles
[Project 5590]: two versions of upgraded and motorized Model Team 5590 truck with 12-speed transmission
[Gearbox theories]: difference between geometrical and progressive gear steps (universal transmission info)
[Building tips]: universal and lego issue building tips for lego gearbox designers
[Junkyard]: my lego transmissions that has been replaced by better designs

Notes:

If you are not familiar with gearboxes you can check my lego gearbox tutorials which are available at either Brickshelf Gallery pictures or YouTube slide shows.: -Part I, 5-speed personal car: pictures, slide show
: -Part II, 12-speed truck: pictures, slide show
: -Part III, Lego gear pairs: pictures, slide show
For serious MOC builders I recommend also these:: -Upshifting procedure for manual 16-speed: slide show
: -Auxiliaries and main gearboxes, page Basic & special designs
: -Universal and lego issues in gearbox designing, page Building tips
: -Universal transmission information, page Gearbox theories

If you have program packet called LDraw, transmission’s LDraw file is also available. If you want to download LDraw it’s available on page http://www.ldraw.org/. And if you want to build something shown here but don’t have needed lego parts it’s worth to check BrickLink.

I’m old school lego builder so transmissions have mainly brick frames but in some cases there is version B available which means new studless frame. In many transmissions axle locations are simple so brick frame can be replaced with studless frame although I haven’t designed version B.

Check here my notations, which I use in my schematic pictures.

All pictures shown here are only unlinked thumbnails. Check “Picture links:” or go to “Brickshelf Gallery:” to see full size pics. For some of my gearboxes there are also ready-to-use building examples. To see those slide shows check “YouTube Videos:”. But you will need to modify my transmissions before they fit to your lego vehicles, also frames will need strengthening to get higher torque capacity. If you are not interested in gearbox theories, model explanations etc. here you can jump direct to Brickshelf Gallery or YouTube videos.

Note equation: overall gear ratio = ratio 1st gear / ratio top gear. It tells you how much slower 1st gear is and how much more torque it gives compared to top gear. For example overall gear ratio 5,00 means that 1st gear gives 5 times the torque but 1/5 of speed compared to top gear. Typical overall gear ratio for 5-speed personal car transmission is about 4,00-4,50 (in close ratio sport cars less than 4), while in mid-range trucks overall gear ratio starts from 9 and heavy trucks need as high values as 15-20. In tractors overall gear ratio starts from 9 but with creeper range values are over 40, in some cases even over 100. Then you don’t need speedometer in 1st gear but calendar. :-)

I have usually scaled ratios so that top gear is shown as a direct drive. It makes easier to understand ratios and gear steps and compare them to the ones of real truck transmissions. Scaling matters only if you calculate the total ratios of the drive line. Direct drive or overdrive gearbox means that top gear is direct or overdrive. Final drive makes total ratios always underdrive so it’s not important to get direct drive or overdrive lego gearboxes.

If your lego transmission has efficiency problems you can check these issues: Are there too large speed increases (ratio less than 0,50) in some gear pairs in some gears? This means especially ratios from output axle to 16 teeth clutch gears (think reversed). Is there large speed difference between 16 teeth clutch gear and its axle? This can be problem in reverse gear so removing it can help. For more information you can check my Building tips.

Some of the gearboxes have two 16 teeth clutch gears connected together. If you have problems to keep them together you have to use bushes to minimize the gap that gear pair makes, check fine tuning. If this is not possible you can try non lego methods like Blu-Tack but don’t glue gears to together, that is against lego’s idea build-unbuild-rebuild. :-)

In many gearboxes I use two 14 teeth thin bevel gears instead of 12 teeth double bevel gear. Unlike other lego gears 14 teeth gear can be two ways on the axle: A) up is located in the middle of a tooth OR B) up is located between two teeth. When you build ratios make sure that both gears are A-oriented or B-oriented. In case A-B you have to turn one of the gears 90 degrees.

[Back to top]

[Links & Notes]

[A.-B.]

[C.-F.]

[G.-J.]

[K.-N.]

[O.]

[P.]

[Q.]

[R.]

[S.]

[T.]

[U.]

Primary content in this document is © Ari Holopainen. All other text, images, or trademarks in this document are the intellectual property of their respective owners.