4631475 Original Excavator Needle Bearing for ZX200-3G

The original needle roller bearing part number 4631475 is a specialized needle roller bearing provided by Hitachi Construction Machinery for the ZX200-3G 20 ton hydraulic excavator (with a total working weight of 19.8 tons). This bearing is mainly used for key transmission parts such as rotating mechanisms, walking reducers, or hinge points of working devices in equipment, to withstand high radial loads and adapt to narrow installation spaces. Its universal model is usually directly labeled as 4631475, belonging to the needle roller bearing series without inner rings or with retainers, complying with ISO 1206 or JIS B1512 standards, and can be interchanged with needle roller bearings of the same size and specifications from brands such as INA, NSK, SKF, etc. However, to ensure matching accuracy and reliability, it is strongly recommended to use genuine original parts from the factory.

This product is an original needle roller bearing made of high carbon chromium steel (GCr15) material, which has undergone carburizing quenching and precision grinding treatment. The raceway hardness is ≥ 60 HRC, and it has extremely high radial bearing capacity (expected dynamic load ≥ 30 kN) and impact resistance. Its structure is designed with a thin cross-section, with a needle roller diameter of ≤ 5 mm and a length of ≥ 3 times the diameter. It achieves the maximum number of rollers in a limited space, thereby increasing the load density. Bearings are usually equipped with stamped steel retainers or fully loaded needle roller designs, with a working temperature range of -30 ℃ to+120 ℃ and a maximum speed of about 3000-5000 rpm under grease lubrication. They may also come with RS or 2RS rubber seals, which effectively prevent dust and leakage. They are suitable for harsh working conditions such as high vibration and high dust in excavators.

Pre installation inspection: Confirm the fit tolerance between the shaft and the seat hole (shaft recommended h6, seat hole H7), surface roughness Ra ≤ 0.8 μ m, and the installation surface must be clean and free of burrs. Lubrication management: Use NLGI grade 2 extreme pressure lithium based grease (such as Shell Gadus S2 V220 or equivalent), with a filling amount of approximately 30% of the internal space of the bearing. Check and replenish after 50 hours of initial operation, and regularly add every 250 working hours thereafter. Operation monitoring: Monitor the operation of bearings for any abnormal metal friction or impact sounds; Check if the temperature rise is abnormal (normally below 80 ℃); If the vibration value exceeds 4.5 mm/s (refer to ISO 10816 standard), the machine needs to be stopped for troubleshooting. Fault diagnosis: If early pitting or peeling occurs, it is often due to overload or poor lubrication; If the cage breaks, it may be due to installation eccentricity or excessive speed. Key points for replacement: Use a dedicated puller during disassembly to avoid direct tapping; When installing new bearings, it is strictly prohibited to heat them above 120 ℃. The cold pressing method should be used for smooth installation; After installation, manually rotate to confirm that there is no jamming.