Lego provides a couple of ways for building a differential, such as this:


and also provides a limited-slip gear like this:

enter image description here


What's the simplest way to combine the two mechanically such that if you have one motor driving two wheels, they can turn at different speeds (i.e. they aren't locked to each other), but at the same time, they will both receive a reasonable amount of force (i.e. if one wheel does not make contact with the ground, the one that does will still apply some force, as opposed it it not spinning at all and the free-hanging one going at twice the speed)?

The simple solution is to just use some belts to drive both wheels, but I would like a geared solution if possible


2 Answers 2


If you haven't seen it, Sariel's limited slip differential technique might do what you want, but it's a little different than what you are asking for:

limited slip differential

This setup doesn't provide a clean way of producing a fixed amount of torque to a wheel if it's partner is running free. It instead simply disables the differential if the wheels have been running at different speeds for too long. This isn't a perfect solution, but it is very simple and may work for you depending on exactly what you are trying to accomplish.

  • This would be great if it somehow reset itself when the two did spin at the some speed, but it will act like a fixed gear at times when it shouldn't Jun 9, 2015 at 15:50

The question is old, but as noted in the accepted answer ("little different"), that does not actually illustrate how to use the Limited-Slip gear. With the limited-slip gear, you can even do without the differential. Note that the weels are on two different axels and the Limited-Slip gear is on the same axel as the opposite normal 24-tooth gear. The Limited-Slip gear does not touch the Crown gear.

Limited-Slip gear only

Of course, it is possible to combine this with a differential:

Limited-Slip gear and Differential

It is also possible to combine the Limited-Slip gear with your type of differential as illustrated here: https://www.eurobricks.com/forum/index.php?/forums/topic/143133-mod-9398-limited-slip-diff-friction/

  • The very first comment on Eurobricks says "That's not a limited slip differential, but the opposite..." and OP agrees with this statement.
    – Alex
    Apr 16, 2020 at 8:21
  • I agree. It is just an answer to this OP here, but not a real differential. As far as I know, a proper differential can't be made with this slip-gear and I'd use worm gears in a Torsen-style solution like the types discussed here: technicbricks.com/2009/03/…
    – Rijk
    Apr 19, 2020 at 11:27
  • It should be gone by now. Apr 19, 2020 at 23:12

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