[martin417]

The practical limitation would be torque output capacity of the gear-set (efficiency also goes down with each stage added). They don't list what the max output torque is, but the shaft is 1/2" diameter 4140, and the carrier is made of 4140. I am not familiar with the carrier design, but I would think the carrier would fail before the shaft. Send Andy a question and ask if there is a rating on max output torque.