YB60004542 Original Excavator Hydraulic Final Drive for Hitachi ZX490H-5A

The part number YB60004542 is an original walking reducer assembly provided by Hitachi for the ZX490H-5A series (with a total working weight of approximately 90 tons) ultra large hydraulic excavator. The large black main reduction gear in the center is integrated with a cylindrical housing with a hydraulic motor interface above. This component is the only power source for driving the single-sided track, and the universal model is usually dedicated to ZX490H-5A and other super large models on the same platform. As the core drive unit of the original factory, its installation flange, output spline, and lower frame must meet the extremely high precision requirements of heavy-duty equipment. It is strictly prohibited to interchange with any other tonnage or model of assembly, otherwise it will directly cause paralysis or structural damage to the walking system.

This product is an integrated drive assembly of a helical axial piston hydraulic motor and a multi-stage planetary gear reducer. The large central gear is the sun gear or ring gear of the final reduction stage, which has undergone carburizing, quenching, and grinding processes to achieve extremely high tooth surface hardness. The cylindrical shell above integrates a hydraulic motor and a 2-3 stage planetary reduction mechanism, with flanges and oil ports distributed on its surface for connecting high-pressure oil pipes, pilot pipelines, drain pipes, and oil injection/exhaust plugs. The hanging ring bolt in the center of the top confirms its enormous weight and must be professionally lifted. Its technical parameters are extremely powerful: the working pressure can reach up to 35MPa, the displacement exceeds 200 cc/rev, the torque is amplified through a planetary reduction mechanism, and the final output torque can exceed 40000 N · m to drive equipment weighing nearly 100 tons. The assembly is equipped with wet multi disc parking brakes, high and low speed switching valves, and safety valves.

Installation specifications: 1 Lifting and alignment: The lifting device with the specifications shown in the picture must be used to lift smoothly. During installation, use guide pins to ensure that the output shaft spline of the assembly is absolutely aligned with the internal spline of the drive wheel, and striking is strictly prohibited. 2. Torque tightening: Use a hydraulic torque wrench to tighten all installation bolts in strict accordance with the cross sequence and ultra-high torque values (usually exceeding 400 N · m) specified in the maintenance manual. 3. Oil filling: After installation, immediately fill the Hitachi designated heavy-duty gear oil (such as SAE 85W-140 API GL-5 or higher specification) through an independent oil filling port, and the oil level must reach the inspection hole standard.