Hirobo HI2521105 Collar 3 x 4-6 x 17 Precision Shaft Collar for RC Helicopters  [HI2521105]

Compact shaft collar for rotor assemblies

This Hirobo HI2521105 collar is a hobby-grade helicopter service part sized 3 x 4-6 x 17. It functions as a compact shaft collar to hold axial position on rotating shafts and preserve alignment during maintenance or adjustment.

Built to work with Hirobo maintenance and rebuild procedures, the collar curbs minor axial play and provides a replaceable locating piece for worn components. It is sold as a service component for hobby rotor assemblies rather than a complete mechanical unit.

Installation notes: slide the collar onto the shaft to the required location and clamp without over-tightening to avoid shaft damage; inspect running clearance after fitting and check rotor alignment at low speed before full operation. For setup and trim, use the collar to lock a chosen position and perform repeat test flights to confirm stability.