Video Presentation

How it works

This steering mechanism enables to have three modes by moving the yellow lever : front steering only, front and rear steering, and front and rear steering in crab mode.

I wanted to use a linkage mechanism as a gearing mechanism would not be good as it gives to much backlash and is bigger. Therefore I have started looking at the Lego Technic Xerion Set, to understand how the linkage multi mode steering works. The idea here was to re-use the principle but adapted it by removing some elements to fit the scale.

I have keep the front axle with the yellow beam which transmits the motion to the rear axle but the inverting mechanism is different. Instead of using a inversion lever with a sliding mechanism, I used directly the yellow beam to operate the rear axle by pushing/pulling the hub of the wheels. By operating directly the left or right rear hub, I can create the crab steering or normal steering in less needed space.

The last thing to figure out was the return to center of the rear axle, as in front wheel steering mode, the yellow beam is not connected to the rear axle, compare to the Xerion Set.  I have managed to do that with end stops and centering parts which make the return to center on the rear axle, and prevent to change mode if the rear wheels are not centered.

How to build ?

The PDF instructions can be downloaded for free on this shop, here is the partlist in the preview below :

About this product