At the gear stage, the engine speed can be transmitted to the output rod via two sets of gears. The final drive is made up of planetary gears and the secondary reducer is realized by a worm gear, which is held in a central position by a set of springs. In the event of an overload, that is, when the output rod exceeds the set torque of the spring, the central worm gear will axially shift, fine-tuning the switch and signal device to provide protection for the system. Acted by the coupling of the externally controlled lever, the output rod is coupled to the worm gear during engine operation and coupled to the handwheel during manual operation. When the engine is not working, the motor drive can be easily disconnected and the handwheel can be connected by simply pressing the lever. Since the motor drive takes precedence over manual operation, a reverse action occurs automatically when the engine is started again. This will prevent the handwheel from being turned on when the engine is running, which will help protect the system.