Hirobo HI2521072 3 x 4 x 4.1F Shaft Collar for Helicopter Parts  [HI2521072]

Product details and application

This HI2521072 collar is catalogued under Hirobo helicopter general parts and carries the sizing 3 x 4 x 4.1F to guide fitment with shafts and adjacent components in model rotor assemblies.

The primary role of the collar is to locate and retain components on a shaft, reducing unwanted axial movement. It is used as a small spacer and locating element where precise spacing is needed, for instance between gears, bearings or linkage points.

Fitment tips: remove burrs and contaminants from the shaft, position the collar where required, and secure it following the original fastening approach. When adjusting for setup, make small positional changes to fine-tune linkage geometry or correct axial misalignment, and perform low-speed bench checks before any flight attempts.