4430716 Original Excavator Rotary Gearbox Parts Bearing for ZX330 ZX330-3 ZX350-3 ZX360-5A ZX870-5B

Part number 4430716 commonly refers to the rolling bearings (commonly described as cylindrical roller bearings) inside the rotary motor/rotary reducer (rotary gearbox) in Hitachi's original factory system. It is a precision load-bearing component used to support rotating pairs such as planetary carriers/output shafts in rotary drives. In the public part number clues, it often appears in the context of "rotary motor gearbox" maintenance for ZAXIS-3 generation models such as ZX200-3/ZX240-3. However, due to the fact that the same bearing number may not be universal in different versions of the gearbox (gear stage, housing hole position, pre tightening method), there is no safe "universal part number" that can be used interchangeably; The most stable method for procurement is to provide: the complete machine model+serial number+photos of the nameplate of the rotary motor/reducer+the actual old bearing/outer ring engraving, and lock the 4430716 specification and clearance level that are completely consistent.

As the original factory grade bearing inside the rotary reducer, it needs to work in a high radial load+impact+micro slip/edge load environment for a long time. The common form is cylindrical rollers (bearing heavy loads/high stiffness) or tapered rollers/deep groove balls at corresponding positions. The inner/outer rings and raceways are precision ground and heat-treated to control the cylindricity, roughness, and P5/P6 rotation accuracy. They are equipped with engineering plastic/stamped steel retainers and contact seals or sealing grooves, which are resistant to gear oil immersion and centrifugal oil throwing. Its core value is to "catch and stabilize" the force of planetary transmission, ensuring that there is no abnormal clearance during rotation start stop, and that the meshing is not biased, while also avoiding premature fatigue pitting and abnormal noise of the gearbox housing.

It should only be operated during the disassembly and overhaul of the rotary reducer - do not add oil or forcefully flush it from the outside in daily life. Typical signals include: positioning "drifting" during platform rotation, slight slippage after stopping rotation, or heating at the gearbox housing/side cover, and a sudden increase in metal shavings. After opening the box, pay attention to whether there is pitting/peeling on the raceway and rollers, cracking on the cage, and whether the inner ring rotates around the shaft neck (discoloration/polishing). Use an inner diameter gauge to check whether the fit with the shaft/hole exceeds the tolerance. The installation must be carried out according to the drawings with correct fit (mostly interference fit/transition), specified torque and locking method (nut/snap spring/end cap gasket), and the grease/oil level must be restored according to the requirements of the reducer; If the shell hole has worn out beyond the tolerance or the shaft neck is pulled, simply replacing the bearing cannot solve the problem, and the shell/shaft assembly needs to be repaired or replaced.