This is a compact 2 speed automatic gearbox design. Instead of using a differential to react to torque on the output it uses the force on the gear teeth to push a liftarm to automatically change the gearing ratio to the 2nd speed once the torque threshold has been exceeded. The automatic gearbox will switch back down to the first speed once the torque on the output is reduced by using two rubber bands to pull back the liftarm. The first speed is simply a 1 to one ratio and the second speed is a 0.6 ratio. The design can be easily modified to change the the second gear speed to other ratios such as 0.36 or 0.2.

 

Have you tested this in a vehicle? I feel like it would just transfer the power to the lower gear ratio because the differential would slip immediately. Still a really cool concept though.

No I haven't tried it in a vehicle - not all automatic gearboxes have to go in vehicles LOL ;) You can set the change over torque point by increasing the rubber band strength. In this demo I had 2 bands - but could increase that to 3 or 4 etc. Also you can gear down after the automatic transmission to the wheels so you see less torque at the transmission point. But yes I will try it in a vehicle sometime!