Perkins 1103 Series Workshop Manual page 21

20
Systems Operation Section
Illustration 14
24 Volt Starting Motor
(1) Terminal for connection of the ignition
switch
The starting motor turns the engine flywheel. The
rpm must be high enough in order to initiate a
sustained operation of the fuel ignition in the
cylinders.
The starting motor has a solenoid. When the ignition
switch is activated, voltage from the electrical
system will cause the solenoid to move the pinion
toward the flywheel ring gear of the engine. The
electrical contacts in the solenoid close the circuit
between the battery and the starting motor barely
before the pinion engages the ring gear. This
causes the starting motor to rotate. This type of
activation is called a positive shift.
When the engine begins to run, the overrunning
clutch of the pinion drive prevents damage to the
armature. Damage to the armature is caused by
excessive speeds. The clutch prevents damage
by stopping the mechanical connection. However,
the pinion will stay meshed with the ring gear until
the ignition switch is released. A spring in the
overrunning clutch returns the clutch to the rest
position.
(2) Terminal for connection of the battery
cable
Alternator
Illustration 15
(1) Shaft for mounting the pulley
The alternator produces the following electrical
output:
• Three-phase
• Full-wave
• Rectified
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