(1) When the moving cone is unstable, it is difficult to adjust the discharge outlet to the design requirements, and the moving cone liner and the fixed liner often collide when they are small;
(2) The fixed spring is unstable and bounces back and forth;
(3) The serrated thread connecting the adjusting ring and the fixing ring is easy to become rough, and the adjusting ring is not easy to disassemble;
(4) The lock cylinder is easy to be damaged and leak oil;
(5) The temperature of the lubricating oil is high, dust and water enter, and it is easy to foam;
(6) The copper washer at the joint between the fixing ring and the frame is easy to be damaged and fall off;
(7) Ball bearings, frame bushings and tapered bushings are easily damaged.