4472905 Original Excavator Needle Bearing for ZX870-5A

The original needle roller bearing part number 4472905 is a key rolling support component in hydraulic pumps for large excavators such as Hitachi ZX870-5A. It is mainly suitable for ZX-5A series large models such as ZX870-5A and ZX890-5A, and may also be compatible with Hitachi excavators of similar tonnage such as ZX870H-3 and ZX870R-3. This bearing is usually installed on the main shaft or gear shaft of hydraulic pumps to support high-speed rotating shaft components, withstand high radial loads, and ensure transmission accuracy. When ordering, the complete model and hydraulic pump serial number of the equipment must be provided to ensure that its inner diameter, outer diameter, and width dimensions match the original pump assembly perfectly.

This product belongs to solid ring needle roller bearings, usually made of high-strength alloy steel (such as GCr15), and undergoes carburizing quenching and precision grinding treatment to ensure wear resistance and dimensional stability under high pressure and high-speed working conditions. Its structure includes an outer ring, needle rollers, and a cage, and may be designed without an inner ring (such as the NK series), directly using hardened shafts as raceways to maximize radial space savings. As an original component, its dimensional accuracy, needle roundness, and heat treatment hardness are strictly matched with Hitachi's original hydraulic pump, ensuring strong load-bearing capacity and smooth operation, avoiding pump abnormal noise, shaft wear, or early failure caused by insufficient precision of auxiliary components.

It is recommended to check the cleanliness of the hydraulic oil (NAS level 9 or below) every 500 working hours, and monitor the pump body for any abnormal continuous hissing or knocking sounds. This may be a sign of pitting corrosion on the bearing raceway or damage to the retainer. Lubrication and replacement: The bearing is usually lubricated with grease or oil. If it is lubricated with grease, it is necessary to regularly add the specified brand of high-temperature and high-speed lubricating grease according to the maintenance manual; If it is oil lubrication, it is necessary to ensure the cleanliness of the hydraulic oil. Disassembly and installation: When replacing, a dedicated puller or press should be used, and direct tapping is strictly prohibited; Before installation, it is necessary to clean the shaft neck and bearing seat hole, and ensure that the fit tolerance (usually interference fit) between the bearing and the shaft/hole meets the requirements.