A Lego Technic multi mode crab Steering at mini scale, with free building instructions.
After a discussion with DyensCreations (Did you know him ? Awesome work he does) on the subject to create a multi mode steering at small scale, I wanted to try to figure out to create one. 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. I think making a multi mode steering with gears is only possible if you have a proper return to center on the rear axle to compensate the backlash and therefore more needed space that we have at mini scale. 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.
Here is the video explanation :
Of course at this scale, it is not possible to power the wheel, but it will be mainly used for manual creations which require compact steering system. You can see the needed parts here, but can of course adapt it in functions of your part collection. You can download the instructions by adding the free purchase to the cart and fill the form :
See it on the shop