For XRB SR: Main Transmission Gear HI0301045 by Hirobo  [HI0301045]

Primary drive gear for XRB SR

The HI0301045 main gear is the specified replacement rotor component for XRB SR helicopters. It transmits motor torque to the rotor head on RC-scale helicopters and is intended for use as a service or spare part during repairs and scheduled maintenance.

To install, experienced modellers should remove the canopy and rotor head as required, confirm shaft seating and bearing health, then mount the gear making sure axial alignment is correct. Check mesh and clearance by turning the main shaft slowly by hand before power-up, and fine tune using shims or spacers if engagement is uneven.

In tuning the drivetrain, this gear affects mesh uniformity and overall drivetrain smoothness more than trim handling. Correct mesh helps lower noise and wear while keeping rotor and tail responses consistent. Include regular inspections for tooth damage or runout as part of your pre-flight routine.