Hirobo HI2521080 Collar for RC Helicopter Parts 2.6 x 4 x 12S  [HI2521080]

This Hirobo HI2521080 collar is an RC-scale shaft stop intended for general helicopter service work. The item code 2.6 x 4 x 12S denotes the nominal dimensions used by builders to match collars to shafts and small linkages.

The collar's role is retention and positioning, sitting on a shaft to limit axial travel and help maintain alignment under load and handling. It is appropriate where a compact axial locator is needed in rotor or transmission subassemblies.

Fitting is simple for routine maintenance: slide the collar to the chosen position on the shaft, align it with adjoining parts, and fasten according to the original assembly practice. Recheck the seating and run an initial slow spin to confirm smooth operation and absence of play.

As a tuning item, the collar offers subtle control over shaft endplay and alignment. When addressing rotor or gearbox spacing, change or relocate collars to achieve correct stack heights and to reduce lateral movement without altering the main components.