Hirobo HI2521080 Collar 2.6 x 4 x 12S shaft collar for RC helicopter parts  [HI2521080]

This Hirobo HI2521080 collar is an RC-scale shaft collar intended for use in helicopter general parts and maintenance. The item designation 2.6 x 4 x 12S describes the nominal sizing used by model builders to match collars to shafts and small linkages.

Functionally, this collar is a retention and positioning component that sits on a shaft to limit axial movement and help keep small assemblies aligned during flight and ground handling. Use it where a compact axial stop or locator is required in rotor or transmission subassemblies.

Installation is straightforward for model maintenance: slide the collar onto the shaft at the required position, align with mating parts, and secure per the original assembly method. Inspect fit and alignment after installation and re-check during initial test runs to confirm there is no binding or unintended play.

Tuning role: as a small but precise locating part, the collar can affect minor shaft endplay and alignment. When adjusting rotor or gearbox spacing, replace or reposition collars to restore correct stack height and minimise lateral movement without modifying primary components.