Hirobo HI2521125 Collar 3 x 4-6 x 15.5 for RC Helicopters  [HI2521125]

Helicopter collar application notes

Intended for RC helicopter assemblies that call for a 3 x 4-6 x 15.5 collar, this component acts as a spacer and alignment aid in compact drive and rotor systems. It helps maintain the axial location of shafts and the spacing between mating parts.

Installation is dependent on the model's fastening approach; the collar is usually fitted over the shaft and secured by the model's clamp or screw arrangement. Confirm shaft diameter and mating fit before final tightening to prevent any play that can affect balance or drivetrain smoothness.

For servicing and tuning, the collar provides a stable mechanical reference to fine tune axial clearance and to return gears, hubs, or linkages to known positions. This helps keep pitch and tracking consistent after maintenance cycles.