Hirobo HI2521081 4 x 5 x 6.5S Shaft Collar for RC-scale Helicopters  [HI2521081]

Precision shaft collar for scale helicopters

This Hirobo HI2521081 collar is an RC-scale accessory engineered as a compact radial clamp to secure axial position on helicopter shafts. The part label states nominal sizing so model builders can confirm fit against a shaft diameter before installation. The collar functions mechanically to prevent unwanted axial movement of gears, bearings, or rotor components during bench setup and ordinary maintenance.

Installation is straightforward: confirm the collar dimensions match your shaft, slide it to the required location, and fasten with the recommended method or standard hardware. For consistent results, clean mating surfaces and recheck endplay after tightening. The collar is handy when trimming or tuning to hold alignment while adjusting blade pitch or spindle position.

Do not guess torque settings; follow your airframe or component manufacturer's guidance to avoid damaging shafts or nearby parts. Treat and fit this item strictly as an RC-scale helicopter spare part.