Marathon — Main Rotor Installation
Repair & overhaul
From a Marathon service manual — check it applies to your exact model before use.
Before you start
- Special care must be taken when installing the rotor assembly; winding damage could result if rotor hits the main stator.
Procedure
- Grease bearing cavity and bearing with Mobil® Polyrex® EM grease (or equivalent).
- Using rotor lifting fixture and hoist, install rotor assembly into main stator through drive end.
- Carefully feed the rotor leads through the front end bracket shaft hole as rotor is installed.
- Single bearing: slide SAE adapter over fan and secure to main stator with capscrews.
- Two-bearing: insert two guide pins in rear bearing lock holes; fill drive end bracket grease cavity 1/3 to 1/2 full.
- Mount the drive end bracket with capscrews; torque bearing cap capscrews to 25 ft-lb (34 N-m).
- Single bearing: install drive discs; torque to 192 ft-lb (260 N-m).
- Install outer bearing cap on exciter end; torque to 25 ft-lb (34 N-m).
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Bearing cap capscrews 25 ft-lb (34 N-m)
- Drive disc capscrews 192 ft-lb (260 N-m)
- Grease cavity 1/3 to 1/2 full
Source: Marathon service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.