RC Helicopter Shaft Collar HI2521081 (4 x 5 x 6.5S) by Hirobo  [HI2521081]

Shaft lock component for model helicopters

This Hirobo HI2521081 collar serves as a simple radial locking part to maintain axial position on helicopter shafts. The nominal dimensions printed with the part let hobbyists verify compatibility with their shaft before committing to installation. Its role is purely mechanical, preventing unwanted axial travel of gears, bearings or rotor fittings while you work on the airframe.

Fitting is simple: check the collar dimensions against your shaft, place it where needed, and secure using the advised hardware or standard methods. For repeatable outcomes, wipe mating surfaces and confirm endplay after tightening. Use the collar as an alignment aid when trimming blade pitch or positioning spindles.

Avoid improvising torque; always refer to your airframe or parts manufacturer's recommendations to prevent damage to the shaft or surrounding components. This item is intended as an RC-scale helicopter spare.