Hirobo HI2521112 3 x 5 x 11 Shaft Collar for RC Rotors  [HI2521112]

Overview and purpose

This small RC shaft collar is listed as HI2521112 from Hirobo and is defined by its 3 x 5 x 11 dimension. It serves as a locating and retaining collar for rotating shafts and compact assemblies commonly found in helicopter hardware, offering a simple mechanical stop or clamp point without altering major components.

The collar's main function is positional control: it secures shaft location, limits axial play, and helps keep linked parts such as tiny gear stacks or bearing seats aligned. As a basic mechanical accessory, installers normally check the inner bore and axial length against the target shaft and adjacent parts to ensure a correct fit before final assembly.

Installation notes: slide the collar onto the shaft to the required position, confirm alignment with mating parts, then tighten the existing set screw or clamping method used on your model. For repeatable placement, mark the shaft location and verify rotation clearance after tightening. Small shifts in collar placement can help fine-tune mesh or blade tracking without changing larger components.