4610138 Original Excavator Swing Motor for Hitachi ZX200-3

The original rotary motor part number 4610138 is a rotary motor assembly provided by Hitachi Construction Machinery for the ZX200-3 medium-sized hydraulic excavator (with a total working weight of 20300kg). This motor is mainly suitable for Hitachi ZX200-3 and its derivative models (such as ZX200-3G, ZX210LC-3) equipped with ISUZU AI-4HK1X direct injection turbocharged engine, and is also compatible with models such as Sumitomo SH200-5 and Shengang SK200-8 on the same platform. Its common model is often labeled as the 4610138 series, which belongs to the axial piston hydraulic motor of Kawasaki or KYB brands. It is usually directly connected to the slewing bearing through a slewing reducer and is responsible for driving the 360 ° stepless rotation of the upper platform. It is the core power unit for the steering and positioning of the excavator working device.

This product is an original hydraulic rotary motor with a slanted disc axial piston structure. It has a rated working pressure of 34.3MPa (main pump pressure), a displacement of approximately 130-140cc/rev, and a maximum output torque of ≥ 5000N · m. The shell is made of high-strength ductile iron, and key components such as the internal plunger, cylinder body, and distribution plate are carburized, quenched, and precision ground. Combined with a double lip skeleton oil seal and O-ring sealing system, it can withstand continuous high pressure, high-frequency reversing, and impact loads. The motor integrates a parking brake (normally closed multi disc brake) and a swing buffer valve, which can automatically lock in case of pressure loss and effectively suppress inertial impact during stopping. As an original component, its flow pressure characteristics, response speed, and thermal balance performance are strictly matched with the ZX200-3's dual variable plunger pump+main control valve hydraulic system, ensuring smooth, precise, and efficient rotary motion.

Daily inspection: It is recommended to check the motor housing for oil leakage and cracks every 250 working hours; Is the oil pipe joint loose; The oil level and pollution level of the gear oil in the rotary reducer (according to SAE 80W-90 GL-5 standard). Operation monitoring: Monitor whether there is any abnormal noise or jamming during rotation; Observe whether the rotation speed is uniform (normal no-load rotation is about 12-15rpm); Is the instrument panel rotary pressure gauge ≤ 5MPa at idle and ≤ 25MPa during operation. Fault diagnosis: If there is weak rotation, pause or unilateral non rotation, priority should be given to checking the pilot oil circuit pressure (standard 3.5MPa), main pump flow rate and main control valve core; If there is rotational slippage (automatic rotation after parking), it is mostly due to wear of the brake friction plate or failure of the buffer valve spring. Key points for replacement: Thoroughly clean the external oil stains before disassembly; Use a dedicated puller to separate the motor and gearbox; When installing a new motor, apply molybdenum disulfide grease to the spline shaft and tighten the fixing bolts 2-3 times in a cross sequence (torque 120-150N · m); Add hydraulic oil of the designated model from the original factory (such as HV46) and evacuate the system air.