Hirobo HI2500047 Shielded Ball Bearings 12 x 21 x 5 mm - 2 pcs  [HI2500047]

Compact 12 x 21 x 5 bearings for shafts and gears

Included are two Hirobo shielded ball bearings sized 12 x 21 x 5 mm, packaged as a 2-piece set for hobby use. These are suitable for replacing worn bearings in compact drivetrains and rotor assemblies.

The shielded steel construction lowers friction while keeping contaminants out of the race area. Typical applications include small main and tail shafts, gearbox bearings, and other locations where the bore and outer race dimensions match the model's housings. Confirm the fit before final assembly.

Mounting notes: press bearings in by applying force on the outer race or use an appropriate driver matched to the 21 mm OD. Avoid loading the inner race during installation to prevent brinelling. For extraction, a puller or careful heat application to the housing is preferable to prying on the bearing faces.

Routine care: clear dirt and metal shavings before fitting, use a light bearing lubricant if appropriate for shielded units, and check shields for deformation. Properly running bearings reduce drivetrain slop and improve control response.

Storage and service intervals: retain bearings in a dry, protected container and replace them if you detect noise, roughness, or excessive play. Regular inspection after heavy flying or running is recommended.