Hirobo HI2521131 Collar 2 x 4 x 12 - RC Helicopter General Part  [HI2521131]

Axial positioning collar for model rotors

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.

To fit the collar, locate the required axial position on the shaft, align surrounding components, and fasten using the model's existing hardware method. Make sure both shaft and collar contact surfaces are clean before tightening to ensure a snug seat and minimal movement.

During setup and tuning this collar functions as a positional stop that helps maintain alignment of blade grips, gears, and spacers. If you detect shaft end play or unusual vibration, include the collar clamping and seating in your inspection routine.