The DC disc brake of the electric hoist motor is mounted on the end cover of the motor shaft. When the crane duty motor is connected to the power supply, the electric hoist motor works at the same time. Because of the electromagnetic suction, attracts the armature and the compression spring, brake disc on the armature end cover is disengaged, crane duty motor running. When the power is turned off, the electromagnet electric hoist motor without magnetic force, the spring pushes the armature to the brake disc, the effect of friction torque, braking the motor stop immediately; our factory also produces the corresponding KDA050 dual speed motor. Electric hoist motor power supply by the rectifier in the motor junction box, and below 3 kilowatts to 4 kilowatts and above AC220V-DC99V, AC380V-DC170V (special time can also be in accordance with the requirements of the factory design such as (DC24V)), KDA050 series electric hoist motor, can move quickly after the realization of motor power loss. Fast braking time KDA0150 motor is less than 0.15 seconds, KDA0100 motor is less than 0.20 seconds, the crane duty motor can be based on user requirements by changing the wiring box wiring to achieve slow braking. This series motor has small noise and reliable braking performance. Its working principle is: when the motor braking power, braking motor by 220V 198V DC AC rectifier, then the electromagnetic armature is attracted, the brake disc is rotating, and electric hoist motor but free rotation. When the electric hoist motor is energized when the solenoid energized, the armature is immediately spring-loaded, the brake disc and the motor rear cover are pressed together to stop rotating.