We mounted the arm onto the robot. It has a maximum height of 42â, meaning that it can stack 10 stones high, but it is really maxed out at that point. Also, the twin motors and gear box really would over-drive the lift – too much power and torque. The motor mounts and shafts were deforming. So, we tried using only one Andy Mark 60 gear motor. The lift is much smoother and easier to control. See below for the revised configuration. We have been chasing our tails trying new things with this lift. We think we are getting close to becoming knowledgeable about what we can and cannot do – what is practical and what is not practical.