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

Shaft collar function and use

The HI2521072 is an RC shaft collar offered as part of Hirobo's general helicopter parts. The 3 x 4 x 4.1F dimension identifies the collar's intended shaft fit and axial width when assembling rotor components.

As a locating device the collar holds components in position along the shaft to control axial play and maintain set clearances. It is commonly used where precise spacing is required, for example between bearings, gears or control linkages in the drive train.

Installation advice: inspect and clean the shaft before fitting, slide the collar into place, then secure using the model's original retention method. For tuning, reposition the collar in small steps to refine linkage geometry or correct slight axial offsets, checking rotation and movement on the bench after each change.