Hirobo HI2521027 Ball Bearing Collar 3x6x2.5  [HI2521027]

Ball bearing collar for helicopters

This compact Hirobo collar is intended as an RC-scale accessory to locate and retain 3x6x2.5 mm ball bearings within helicopter linkages and small rotating subassemblies. The part is a simple mechanical spacer that helps control axial play where bearings meet shafts or housings, making it useful when rebuilding or maintaining rotor heads and control link pivots.

Installation is straightforward: confirm the bearing matches the 3x6x2.5 mm sizing printed in the product name, position the collar so it seats against the bearing race or housing face, then verify free rotation and correct axial clearance before flight. For fit checks, measure the bearing inner and outer diameters and the mating shaft or bore rather than relying on model numbers alone.

In tuning or repair work the collar's role is mechanical rather than functional electrical, it helps maintain consistent bearing position which can reduce unwanted endplay and improve linkage repeatability after routine maintenance.