Hirobo HI2521071 Collar 3 X 7 X 4S for RC helicopter assemblies  [HI2521071]

Shaft collar for alignment and service

This part is an RC-scale replacement designed for use in Hirobo helicopter assemblies where a compact collar is required to control axial position or spacing. The 3 x 7 x 4S marking identifies its compact size, making it suitable as a spacer or locating collar in rotor head linkages and similar components.

To fit, slide the collar onto the relevant shaft or pin and secure it using the model's existing fastening arrangement. After installation, check axial alignment and any residual play, then tighten the host fastener to the manufacturer's recommended torque to avoid loosening while flying.

For setup and tuning the collar provides reliable spacing and repeatable positioning; it is practical when making blade pitch adjustments, correcting blade grip alignment, or replacing worn locating pieces during scheduled maintenance.