I diverted the use of this mechanical gearbox by removing the DC motor and replacing it with a stepper motor. In this case it is necessary to cut the periphery of the DC motor and saw its axis to recover the pinion which connects the DC motor to the reducer. The DC motor can not be used later. Then we can fix the pinion on a small stepper motor. This assembly makes it possible to obtain very low speeds of rotation associated with a high engine torque. The angular resolution is less good in practice than in theory given the large number of small gears in the gearbox that induce a large mechanical play. Fortunately it can be pretty well fixed by software if the stepper motor is controlled by computer.
