4178173 Excavator Hydraulic Pump Bearing Seat Locking Nut for Hitachi ZX200-5G

Part number 4178173 is an original bearing lock nut specially designed by Hitachi for the hydraulic main pump of the ZX200-5G hydraulic excavator. This nut is a key fastener for the hydraulic pump drive shaft bearing assembly, used to precisely lock the drive side bearing onto the pump shaft and adjust the bearing preload. Mainly designed for ZX200-5G models. This nut is also applicable to other models of the same series that use the same main pump assembly, such as ZX200-5A, ZX210-5G, etc. As the core fastener of the original factory, its thread specifications, strength level (usually level 8 or higher), and special locking structure are fully matched with the pump shaft threads and subsequent locking gaskets/devices

This product is a slotted locking nut made of high-strength alloy steel precision machining, with a silver gray ring shape and high-precision threads on the inner hole. The outer ring is designed with multiple edges (usually hexagonal or specialized tooth shapes) to facilitate the use of a wrench to apply force. One of its core features is the evenly distributed radial grooves machined on the top or side, which is a key mechanical anti loosening design that matches the convex teeth of the dedicated locking gasket to prevent the nut from loosening under high-speed rotation and vibration.

Inspection and replacement: This nut is only involved in the disassembly and assembly of the hydraulic pump during major repairs, replacement of bearings or transmission shafts. No special maintenance is required on a daily basis, but if there is abnormal axial movement or abnormal noise in the pump body, it should be checked for looseness during troubleshooting. This nut is a high-precision key fastener, and in principle, it must be replaced with a new part after disassembly. It is strictly prohibited to reuse it, as its locking performance and thread state may have changed due to plastic deformation during initial installation.