Dog Gear?

[Matt382]

The AndyMark Supershift also uses a dog gear: http://andymark.biz/am-0114.html

Simbotics used a Dewalt transmission that does not backdrive, so they don't need to power the motor to hold it in place (this is important because you don't want to put power to the motor when the motor isn't moving). The Supershifters and the Gen 2 can backdrive, so you would need to further modify them so they don't backdrive if you wanted to do a winch like Simbotics did.