The robot's legs must be pushed down against the ground to lift up the robot's body. They are also required to lift up, above the surface of the ground to step over obstacles. For this reason, the legs have two sets of pulleys in them, one for picking the leg up, and another for pushing the leg down. In the diagram, the pulleys which raise the leg use yellow string, and the other set uses red string. In reality both strings are green.

It was possible to use the same winch to wind in the strings of both sets of pulleys. When the winch pulls in the yellow string, red string must be let out so that it doesn't prevent the leg from moving. The yellow string is wound around the winch clockwise, and the red string is wound around the winch counter clockwise. When the winch turns clockwise, it takes in yellow string, and lets out red string.