First Ever Lego Trial Truck with Automatic Transmission

World first! I modified slightly my earlier design for an automatic transmission so it could work well in a trial truck. I had to change around some of the gears and supports so that it wouldn’t slip in first or second gear. I also changed the gear-shift mechanism so that it is all lego, no rubber band but instead a spring. It works very well, downshifts going over an obstacle for more torque, then upshifts again for speed when over the obstacle. The trial truck is a quite simple design, it uses my axles from rock crawler project and 3 link flexible live axle suspension. XL motor for power, m with worm gear reduction for steering. Video:

Lego Heavy Duty Automatic Transmission For Trial Truck

The final version of my automatic gearbox, this time using a mechanical “torque sensor” to shift a pneumatic valve, thus changing gears to a lower ratio, giving it more torque for an obstacle. Then, when the resistance on the output shaft lowers, the valve changes directions again, switching the gear back to high speed. Ratios are 1:1 for high speed and 9:25 for the low speed. Video: