It is still difficult to rotate heavy objects with LEGO and hence I designed an ultra compact LEGO compatible ball bearing. it is only 6 studs wide and two studs high. I also added two lift arms. You can put a worm wheel in there to rotate the turn table. The 3D model is available for download from Autodesk. You may need Fusion 360 to work with the model.
This ball bearing is so small that you need a very high resolution printer to get good results. Some of the wall thicknesses could be to small to get printed on low quality printers. I will now be working on a slightly bigger version that can be printed on more affordable printers.
This is a very small, robust, reliable and easy to maintain buggy. It is ideal for letting your kids play with all day. The design goal was to make a robust car as small and simple as possible. This means most of all no suspension system since that would require the use of CV joints. They are known to break and while they work nicely in LEGO super cars that you carefully push around the floor, it does not work with kids trying to race and crash their RC cars. CV joints will break. Of course it is possible to create a LEGO RC car with suspension and even four wheel drive/steering, but then you end up with LEGO’s own RC Crawler. The goal was to keep it small, simple and robust.
One of the problems I encountered when letting kids play with the RC cars all day is that the axles in the differential tend to slip and move out. I hence build a differential assembly in which the axles are completely locked in and cannot move. The worst thing that could still happen is that a wheel comes off which is easy to fix.
The car uses only one L-Motor and is pretty fast for that. The turning radius is very tight and the car is just fun to drive. The differential makes it perfect to drive around tight corners. The heavy battery pack is right on top of the back axle, giving it the best friction. Well, it does not accelerate like an F1, but it might still make a small difference.