When the cranking circuit is closed, a drive pinion on the armature shaft engages with the teeth on the engine flywheel ring gear to crank the engine. When the engine starts, it is necessary to disengage the drive pinion to prevent the armature from overspeeding and damaging the cranking motor. To accomplish this, the cranking motor is equipped with an over-running clutch within the drive pinion. The cranking motor drive pinion and the engine flywheel ring gear must be matched to provide positive engagement and to avoid clashing of the gear teeth.
Note: Some engines may be equipped with air starters. Contact starter manufacturer for operating characteristics and rebuilding procedures.
The 42 MT cranking motor typically used on the engine has a nose housing that can be rotated to obtain a number of different solenoid positions with respect to the mounting flange. The commutator end cap can be removed to inspect the brushes, in most cases, without removing the cranking motor from the vehicle.
Note: The 50 MT cranking motor is used on heat exchanger-cooled pleasure craft marine engines.
The cranking motor armature is supported by three sintered bronze bearings located, one each, in the nose and intermediate housings, with one in the commutator end cap.
|1. O-ring ||10. Shift Mechanism (Totally Enclosed) |
|2. End Cap (Removal for Inspection) ||11. Two-piece Housing |
|3. Bronze Bearing ||12. O-ring |
|4. Connector Strap ||13. Shaft |
|5. Gasket ||14. Heavy-duty Drive Overrunning Clutch |
|6. Low Friction Bushing ||15. Shaft |
|7. Seamless, One-piece Solenoid Case ||16. O-ring |
|8. O-ring ||17. Shaft Seal |
|9. Sealing Boot ||18. One-piece Brush |