Hirobo HI2521052 Collar 4 x 8 x 4 collar for Hirobo helicopter general parts  [HI2521052]

Collar for Hirobo helicopters

This is an RC-scale replacement collar listed under Hirobo helicopter general parts, supplied as HI2521052. The collar serves as a small retention and spacing component used in assemblies where a 4 x 8 x 4 collar is specified, and is intended for routine part replacement and maintenance on compatible Hirobo models.

The collar's role in a rotorcraft drivetrain or tail assembly is to maintain axial position of shafts and to reduce lateral play when paired with the correct shaft and set-screw arrangement. When replacing worn collars, check surrounding parts for wear so the new collar can restore intended alignment without introducing binding.

Installation is straightforward for technicians familiar with RC helicopter maintenance: remove the retaining hardware, inspect the shaft and neighbouring components for scoring or looseness, fit the collar to the specified shaft section, and secure per the original fastener method. Verify free rotation and correct axial location during a low-speed bench test before flight.

For tuning and setup, use collars like this to fine-adjust axial spacing when aligning gear meshes or blade grips. Small changes in collar placement can affect track and vibration, so make incremental adjustments and record positions for repeatable setup.