4688059 Hitachi excavator ZX870-5G travel motor assembly

Part number 4688059 is a dedicated travel motor assembly (including two-speed axial piston motor + three-stage planetary gearbox + drive sprocket) for Hitachi ZX870-5A excavators, compatible with ZX870-5A and heavy-duty models on the same platform such as ZX670-5A/ZX870H-5A. It is suitable for Isuzu 6WG1 engines and original hydraulic systems. The motor has a rated pressure of 35MPa, a maximum torque of 12500N·m, a reduction ratio of 23.8:1, a drive sprocket with a pitch of 216mm and 21 teeth, an input speed of 0-2800rpm, and an output speed of 0-117rpm. The total weight of the assembly is about 480kg. It adopts a floating oil seal (temperature-resistant from -40℃ to 100℃), with a protection class of IP67, and is suitable for the original track assembly, ensuring stable transmission of travel power and efficient operation under heavy-duty working conditions.

Its core function is to convert the high-pressure oil output by the hydraulic pump into travel driving force. The three-stage planetary gearbox realizes large torque output. The hydraulic motor has a built-in balance valve (to prevent slope slipping) and an overload relief valve (to protect the system pressure ≤38MPa). The floating oil seal isolates hydraulic oil from gear oil, preventing dust, water and leakage. The gears are made of 20CrMnTi material (carburizing and quenching hardness HRC58-62), and the bearings are original SKF (rated service life ≥12000 hours). It is suitable for heavy-duty working conditions such as mines and rocks (operating temperature -40℃ to 85℃), with an average service life of ≥9000 hours. It has a fast forward-reverse switching function (response time ≤0.4s), ensuring stable and accurate travel actions and preventing component damage.

Before replacement, disconnect the negative pole of the battery and release the pressure of the hydraulic system. When disassembling, remove the fixing bolts with a torque of 130-150N·m, mark the oil pipe interfaces (to avoid wrong connection), and clean the mounting surface (free of oil stains and impurities). When installing, replace with a new floating oil seal (apply grease), tighten the bolts symmetrically (130-150N·m), add gear oil (API GL-5 85W-140) to the oil level line after connecting the oil pipes, and perform a test run (15 minutes each for forward and reverse rotation, no abnormal noise/leakage). This travel motor can increase travel traction by 25%, reduce travel failure shutdown rate by 45%, decrease hydraulic oil loss by 18%, extend the service life of tracks and drive wheels, improve the overall operation efficiency of the machine, and reduce maintenance costs.