4408361910 Original Hitachi gear pump for Hitachi ZW550 loader.

Part number 4408361910 is a dedicated high-pressure gear pump (power source for hydraulic pilot/auxiliary systems) for Hitachi ZW550 series (including ZW550-6/ZW550-G) wheel loaders, compatible with ZW550-6/ZW550-G, ZW550-5 series, as well as ZW450-6/ZW500-6 and other large loaders. It is suitable for the high-pressure hydraulic system of Isuzu 6WG1/Cummins QSX15 engines, adopting a two-stage spur gear meshing structure, with a rated working pressure of 25MPa (peak 31.5MPa), rated flow rate of 80-100L/min (2000rpm), gear module 3.5, number of teeth 14, equipped with chrome-plated alloy gears and high-strength cast iron pump body, operating voltage DC24V (solenoid valve control), operating temperature -25°C to 80°C, and protection class IP67. It is responsible for steering pilot, brake boosting, and hydraulic accessory drive, ensuring hydraulic response speed and system stability under heavy load conditions.

Core functions include high-pressure oil delivery (providing stable pressure oil for steering gear, brake valve group, pilot control valve), dynamic flow/pressure compensation (adapting to engine speed changes), overload protection (built-in relief valve with set pressure 31.5MPa), oil temperature/level monitoring interface, and oil contamination warning (integrated differential pressure sensor). The pump shaft is made of nitrided alloy steel, and the seals are made of fluororubber, suitable for oil temperatures from -40°C to 120°C, with strong adaptability to anti-wear hydraulic oil (ISO VG46). The Mean Time Between Failures (MTBF) is ≥12000 hours, supporting online pressure calibration, suitable for extreme working conditions such as dust, heavy load and vibration, ensuring long-term efficient operation.

Release system pressure and disconnect the negative pole of the battery before replacement. When disassembling, remove the pump body fixing bolts with a torque of 10-12N·m, and avoid knocking the gears and shafting. When installing, replace the fluororubber sealing ring and apply thread locker. The coaxiality error between the pump shaft and the drive end shall be ≤0.1mm, and the bolts shall be tightened symmetrically. After installation, calibrate the pressure to 25MPa with a hydraulic tester, remove air from the system and check for leaks. This gear pump can reduce the incidence of hydraulic system failures by more than 35%, increase the steering/braking response speed by 20%, reduce power loss by 15%, extend the service life of hydraulic components, and reduce maintenance costs and downtime.