The basic characteristic of the load of mining machinery is uneven impact load. When the belt moves normally, impact load will also have a great impact on the motor, pulley and belt, which results in motor overcurrent, heating, too fast abrasion of belt and pulley. On the one hand, it will increase the cost of equipment and spare parts of mining machinery, and on the other hand, it will increase the failure time of mining machinery, and reduce the operating rate of equipment. The loss is very large. Therefore, it is necessary to protect the motor of mining machinery and equipment from overload. The common method of motor overload protection is to add a hydraulic coupling between the motor and the pulley of mining machinery. Hydraulic coupling has strong overload protection ability.