Makita 421908-9 Spare Part - SEAL RING HR4011C /4001C
Original Makita 421908-9 — Seal Ring
Description:
A genuine Makita seal ring (part no. 421908-9) used in the crank/housing area of Makita SDS‑max rotary hammers. This sealing ring sits near the crank cap and air‑pipe assembly inside the crank housing and restores the air/dust seal that keeps debris out of the hammer/drive mechanism and maintains proper pneumatic action of the tool. The part is listed as item 74 in Makita’s HR4001C/HR4011C parts breakdown and is shown in the exploded diagram where it interfaces with the crank cap/air pipe.
Fits (example models):
Commonly used on Makita HR4001C and HR4011C rotary hammers — check your tool’s parts diagram or model/type to confirm compatibility before installing.
Why replace it:
Worn, torn or compressed seal rings allow dust and grit into the crank/air passages, which accelerates wear on bearings and internal parts and can degrade hammer performance. Replacing part 421908-9 restores the intended sealing and helps extend the life and reliability of the crank/hammer assembly.
Note:
Refer to your Makita parts diagram or service manual (item 74 on the HR4001C/HR4011C diagram) for installation orientation and to confirm fit for your specific tool serial/type.
Jump straight to the Makita spare parts diagrams:
Compatible models this part will fit:
