Hitachi 992-503 Spare Part - Washer

Hitachi part 992503 — Washer (genuine Hitachi) — replacement washer used as a spacer/retaining washer in the gearbox of several Hitachi/Hikoki rotary-hammer models. It’s a simple hardened-steel washer that seats against the gear stack to control endplay and keep the second/third gears aligned and meshing correctly.

Fits example models: DH25PB and DH25PA (rotary-hammer series) and commonly appears in the parts breakdown for DH28PC / DH28PD tools and related DH30PC2 models — check your model’s exploded parts list to confirm placement.

Why this part matters: a worn, bent or missing washer 992503 can allow excessive gear play, noisy operation, or premature wear of adjacent gears and bearings. It’s a direct-fit, original Hitachi spare part that slips into the gear assembly and installs without modification. This is one of the standard Hitachi spare parts you’ll want when servicing rotary-hammer gearboxes to restore correct gear spacing.

Quick notes for installation: installation typically requires disassembling the gear cover and removing the crank/gear assembly to access the washer—replace like-for-like and inspect nearby bearings (6001/6000 series) and circlips while you’re in there. This part is a genuine Hitachi item listed in factory parts diagrams for the models above, and is a common single-item purchase among parts for power tools when repairing rotary hammers.