Hirobo HI2521131 2 x 4 x 12 Shaft Collar for RC Helicopter  [HI2521131]

Compact shaft collar for rotor assemblies

This Hirobo collar is a compact RC-scale component intended for use in helicopter general parts where small axial retention is required. The part is identified as HI2521131 and referenced by the 2 x 4 x 12 marking; it serves to locate and hold components on short shafts in model rotor systems.

Installation is straightforward: position the collar at the required axial location on the shaft, align with mating parts, and secure according to the model's hardware method. Confirm the shaft and collar mating surfaces are clean and free of debris before assembly to ensure stable seating and minimal play.

In tuning and maintenance, this collar acts as a simple positional stop that helps keep blade grips, gears, or spacers aligned. When diagnosing shaft end play or vibration, check the collar seating and clamp method as part of routine rotor system inspection.