Hirobo HI0404509 SX bevel pinion gear set for Eagle/Freya/EX/SX  [HI0404509]

Product summary and application

This Hirobo HI0404509 SX bevel pinion gear set is intended as a replacement component for common parts used on Eagle, Freya, EX and SX helicopter platforms. It acts as the driven/driving interface on the motor-to-gearbox axis and is supplied as a matched pair to maintain correct gear engagement in tail or main transmissions that use bevel pinions.

Fitment is established by the model references and intended product path; the set is designed to suit the common mounting patterns and shaft diameters across Eagle/Freya/EX/SX parts. Do not assume compatibility with unrelated frames without checking shaft diameter and spline count in vendor listings or original part diagrams.

Fitting guidance and role in setup: ensure gear faces are parallel and set minimal, nonzero backlash, hand-rotate the drivetrain to check for smooth engagement before applying power, and confirm alignment with any connected spur or bevel gears. Apply a light gear lubricant to tooth surfaces and recheck mesh after a short operational period. Correct pinion fitment helps keep drivetrain timing consistent and reduces noise from worn pinions.

Fit this matched set as part of routine servicing or when diagnosing drivetrain faults on compatible Hirobo helicopters, and always verify measurements before installation.