Dc reduction motor is a device to adjust the speed of dc motor, upper connection ac power supply, lower connection dc motor. A dc governor converts ac power into two output dc power supplies, one input to the dc motor for magnetization and the other input to the dc motor armature. The dc governor regulates the speed of the dc motor by controlling the dc voltage of the armature. At the same time, the dc motor provides feedback current to the governor. Governor according to the feedback current judgment dc motor speed, and modify the armature voltage output when necessary, to adjust the speed of the motor again.