Genuine Makita Ring Spring — Part No. 233917-4. A hardened retaining (snap) ring specified as "Ring Spring 28" with a nominal diameter of 28 mm, used inside Makita SDS‑Plus rotary hammers to secure internal components on the drive / piston assembly.

What it does: this small circlip holds internal parts (piston / striker / related washers and bearings) in position so the hammer mechanism runs true; a worn or broken ring spring can allow axial play, noise or damage to other internal parts. The Makita parts breakdowns show 233917-4 located with the piston/striker assembly and listed as a service item.

Fits these Makita rotary-hammer models (examples): BHR202 , BHR240 , BHR241 , BHR261, HR2020, HR2230, HR2432, HR2440, HR2450 , HR2470 / HR2470T, HR2475, HR2811F / HR2811FT rotary hammers where Makita lists "Ring Spring 28" as part no. 233917-4. (Check your model's parts breakdown to confirm the same part position.)

Notes: sold as the single ring-spring replacement shown in Makita service parts and included in the hammer service kit lists — exact fit for the models above when the parts diagram shows 233917-4 (Ring Spring 28). Use this genuine Makita part to restore correct axial retention and prevent further internal wear.

Jump straight to the Makita spare parts diagrams:

• Makita BHR202 Parts
• Makita BHR240 Parts
• Makita BHR241 Parts
• Makita BHR261 Parts
• Makita HR2020 Parts
• Makita HR2230 Parts
• Makita HR2432 Parts
• Makita HR2450 Parts
• Makita HR2450F Parts
• Makita HR2455 Parts
• Makita HR2470 Parts
• Makita HR2470FT Parts
• Makita HR2475 Parts
• Makita HR2811F Parts
• Makita HR2811FT Parts

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