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

RC helicopter shaft spacer

Designed for small-scale helicopter assemblies that require a 3 x 4-6 x 15.5 collar, this part provides spacing and alignment in compact mechanical layouts. It helps maintain consistent axial placement of rotor and drive components.

How you fit the collar depends on the model's fastening approach; typically it slides onto the shaft and is secured by the model's clamp or screw arrangement. Always confirm shaft diameter and mating tolerances before final assembly to reduce the chance of unwanted play affecting rotor balance.

During setup and servicing, use the collar to set repeatable axial clearance and to locate gears, hubs, or linkages consistently. This aids in keeping pitch and tracking stable between disassembly and reassembly sessions.