4439383 Hitachi EX3600 excavator swing motor assembly

Part number 4439383 is a high-pressure piston swing motor (integrated with reduction gearbox) specially designed for Hitachi mining excavator EX3600, compatible with EX3600-5/EX3600-6, as well as EX1900-5/EX1900-6/EX8000 and other large mining models. It is suitable for the hydraulic system of Cummins QSX15 engine, with a transmission ratio of 280:1, input torque of 8500N·m, output torque of 2380000N·m, rated working pressure of 35MPa, maximum pressure resistance of 42MPa, rated speed of 8rpm, and weight of 215kg. Adopting radial piston structure + three-stage planetary reduction + wet multi-disc brake, it ensures stable and precise swing under ultra-heavy mining conditions, protects the swing bearing and structural parts, and avoids impact damage.

The plungers and cylinder block are made of silicon nitride ceramic coating + chrome-molybdenum alloy steel, with a hardness of HRC62-65, and excellent wear resistance and anti-seizure performance. The valve plate is made of high-strength alloy, mirror-polished, with a leakage rate ≤0.5L/min. The planetary gears are made of 20CrNiMoA with carburizing and quenching treatment, tooth surface hardness HRC60-64, and strong bearing capacity. The friction plates of the wet brake are made of copper-based powder metallurgy + carbon fiber composite material, with stable friction coefficient, fast braking response and thermal decay rate ≤3%. The seals are made of fluororubber (FKM), suitable for oil temperature environment from -40°C to 120°C, with excellent anti-aging and high-pressure leakage prevention performance. The housing is made of ductile iron QT800-2, after double aging treatment, the deformation is ≤0.05mm, with outstanding impact resistance and vibration resistance. It is recommended to maintain every 2500 hours under normal working conditions, replace the gear oil and seals; shorten to 1800 hours under ultra-heavy mining conditions. There are no failures such as leakage, brake failure and gear wear within the maintenance cycle, which effectively extends the service life of the swing mechanism and reduces the failure rate.

Adopting an overall integrated design, special hoisting equipment (load-bearing ≥250kg) is required for disassembly and installation. Before disassembly, the pressure of the hydraulic system should be released (≤0.1MPa). During installation, the flange bolts should be tightened symmetrically and evenly according to 180-200N·m. After installation, GL-5 85W-140 heavy-duty gear oil should be added to the oil level line, and start the test run to check the swing action, braking performance and leakage. This swing motor can reduce the maintenance cost of the swing mechanism of large mining excavators by more than 50%, reduce the downtime caused by brake failure and leakage, improve the operating efficiency by about 20% under working conditions such as mine stripping and ore loading, and ensure the safe, reliable and precise swing action.