Hirobo HI2521081 Collar 4 x 5 x 6.5S Shaft Collar for RC-scale Helicopters  [HI2521081]

Shaft collar for RC helicopters

This Hirobo HI2521081 collar is an RC-scale accessory designed as a simple radial solution to secure axial position on helicopter shafts. The part identifier includes the nominal sizing information, allowing hobbyists and technicians to confirm fit against a model's shaft dimensions before use. The component's role is purely mechanical within the model, intended to prevent unwanted axial movement of gears, bearings, or rotor assemblies during bench setup and routine maintenance.

Installation is straightforward: verify the part dimensions against your shaft, slide the collar into the required position, and fasten using the model's recommended method or standard hardware. For repeatable results, clean mating surfaces and check for endplay after tightening. The collar can be useful during trimming and tuning to hold alignment while adjusting blade pitch or spindle positioning.

Avoid improvising torque values, instead rely on your airframe or component manufacturer's guidance to prevent damage to shafts or adjacent parts. This item should be treated and installed as an RC-scale helicopter spare part only.