Belparts excavator SH200 JCB220 CX210 20-925315 swing motor assembly repair

The piston-type swing motor is the mainstream configuration for medium and large excavators, adopting a radial or axial piston structure. Its principle is: after high-pressure hydraulic oil enters the motor cylinder block, it pushes the piston to reciprocate along the cylinder block hole, converts the linear motion of the piston into the rotational motion of the cylinder block through a swashplate or eccentric wheel, and then amplifies the torque through a planetary reduction mechanism. Compared with gear-type motors, it has the advantages of large torque, high efficiency (up to more than 90%), and a wide speed adjustment range, which can adapt to different needs of heavy-load excavation (such as mining operations) and fine rotation (such as municipal construction). In terms of function, it can realize stable start-stop and stepless speed regulation of the upper frame, avoid rotational impact damage to the fuselage structure, and solve the "crawling" problem during low-speed rotation through a charge valve, improving operation accuracy.