Hirobo HI2521016 Ball Bearing Collar (A) 4 x 7 x 1.5 mm  [HI2521016]

Ball Bearing Collar for RC Models

This Hirobo ball bearing collar is an RC-scale component intended to control axial location and spacing for small bearings in model assemblies. The designation 4 x 7 x 1.5 indicates the dimensional profile used to match bearing and shaft interfaces, and the part is described as a collar type "A" designed for precise placement rather than load-bearing duties.

In practical use, the collar acts as a spacer and locator that sits against a bearing face or housing to limit endplay. Installation is straightforward on compatible shafts: slide the collar into position against the bearing or into a recess, then secure the surrounding hardware as your model's layout requires. Always confirm inner diameter and outer diameter match the mating bearing and shaft before fitting.

For tuning and maintenance, small adjustments to collar position can affect gear mesh and axial clearance in gearboxes and rotor assemblies. Use the collar to eliminate unwanted shaft movement and to reproduce consistent spacing when rebuilding small RC helicopters or micro drivetrains.