If the abnormal sound of WP worm gear reducer is irregular and loud, it is caused by tooth pitch error or excessive clearance.The ding dangling sound and the tooth rolling sound that cause the vibration of the transmission body are caused by the side clearance of the WP worm gear reducer is too small, and the gear tooth top has a sharp edge and the gear center is not parallel; there is a violent sound when the speed is gradually increased, There is an incorrect knocking sound during meshing, which is mainly caused by the distortion of the working tooth shape of the WP worm gear reducer or the partial defect on the tooth working surface.In the gear transmission, there is a periodic increase and decrease of the sound, which is due to the eccentric distribution of the gear to the center of rotation.