ELECTRICAL EQUIPMENT—Q.11
Fig. Q.9.
Cross Section view of CA 45 Type Starter Motor.
The pinion (6) and sleeve (44), mounted on the
armature shaft (5).
The sliding plunger (11) mounted on the pinion
sleeve.
First (13) and second (41) main switch contacts.
The moving contacts are mounted on the
plunger.
The contact trip-trigger (40).
The ball-locking collar (17) and trip-collar (19)
both mounted on the pinion sleeve.
OPERATION
Engagement of the pinion with the engine flywheel is
made in two separate, but continuous stages.
First Stage
When the starter switch-button is pressed, the
solenoid (10), is energized. The magnetic field draws
the sliding plunger (11) forward v, in (8 mm) to meet the
shoulder (12), on the pinion sleeve (44).
The pinion, now pushed by the plunger, also moves
forward, until the pinion nose commences to mesh with
the engine flywheel.
Simultaneously, the moving contacts, mounted on the
plunger, are also carried forward, causing the first set
(13) to close. The second set (41) held by the trip-
trigger (40) remain open until the first stage is
completed. At this point, the plunger slides fully home
against the stop (45) on the drive end shield.
The first pair of contacts having closed, battery current
flows through the resistance (9) and armature field
windings (24). Since the resistance allows a limited
current only, to pass through the field windings. the
armature rotates very slowly. The electrical circuit is
shown schematically in Fig. Q.11. This completes the
first stage of the operation.
Second Stage
The pinion, already partially engaged and prevented
from rotating by the engine flywheel will be gently
pushed into full engagement by the helix on the slowly
revolving armature shaft. However, just before complete
engagement is reached, the trip-trigger (40) is lifted by
the forward movement of the trip-collar (19) mounted on
the pinion sleeve. This frees the second set of contacts
(41),
