New Holland WorkMaster 50 Service Manual page 670

Engine starting system - Dynamic description
Description of operation
The starting system consists of a starter motor equipped with an electromagnetic starter solenoid, a key switch, a
start relay, several safety switches, and heavy-duty wiring.
Starter components
(1) Reduction Uni Cover
(2) Armature Drive Gear
(3) Motor/Field Coil Housing (Yoke)
(4) Permanent Magnet
(5) Field Coil
(6) Armature
(7) Brush Spring
(8) Brush
Starter motor assembly
The starter motor features a high-speed motor that utilizes a gear reduction unit, an overrunning pinion clutch, (12),
and permanent magnets, (4), in a field coil, (5), for magnetic field induction. The reduction unit consists of a small
drive gear, (2), on the motor armature, (6), which drives an idler gear, (14), in the reduction unit. The idler gear is
splined to the gear on the pinion clutch housing, (12). When the starter solenoid, (10), is energized, the solenoid
plunger, (9), pushes the pinion gear, (13), out, engaging with the engine flywheel. The starter motor then is turning
the flywheel, which rotates the engine. The use of the gear reduction unit allows use of the compact, high-speed
motor and provides more torque and power to turn the engine flywheel. The sliding pinion mechanism is enclosed,
resulting in a more durable mechanism.
Electrical systems - Engine starting system
SEC55CH4PG28
(9) Plunger
(10) Solenoid
(11) Return Spring
(12) Pinion Clutch
(13) Pinion
(14) Idler Gear
(15) Idler Gear Roller Bearing
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