Advertisement
(323)
ELECTRICAL SYSTEMS
CRANKING SYSTEM
10-47
SOLENOID SWITCH
RELAY
BATTERY
TERMINAL
STUD
COMMUTATOR
END FRAME
COMMUTATOR
THRU BOLT . /
COVER BAND
1
ARMATURE
RELAY TERMINALS
PLUNGER
_
SHIFT LEVER
RETURN SPRING
FIELD COIL
DRIVE HOUSING
DRIVE
ASSEMBLY
Figure 10-S3-Cranking Motor, Sectional View-Series 70
tached to the field frame by large screws. The
field coils are connected to an insulated ter-
minal stud on the field frame, through which
current is supplied to the motor.
b. Cranking Motor Drive Assembly and
Shift Lever
The drive assembly is mounted on the motor
armature shaft and keyed to it by splines so
that it can be moved endwise on the shaft by
the solenoid operated shift lever.
It
transmits
cranking torque to the flywheel ring gear, but
allows the drive pinion to rotate freely with
reference to the armature shaft when the en-
gine begins to operate, thus preventing the
armature from being driven at excessive speed
by the
engine.
The drive
assembly
consists of a pinion-and-
collar,
overrunning
clutch,
spring, and shift
collar. The
overrunning clutch consists of a
shell and
sleeve
assembly, which is internally
splined to the armature shaft. The pinion collar
fits within the clutch shell. Four tapered
notches cut in the clutch shell house four hard-
ened steel rolls in position so that they can bear
against the pinion collar. A spring and plunger
presses each roll toward the small end of the
notches and into contact with the pinion collar.
See figure 10-54.
When the clutch shell is rotated by the arma-
ture shaft, the rolls jam between the shell and
pinion collar and force the pinion to rotate with
the shell. When the pinion is rotated by the fly-
wheel ring gear, after the engine starts, the
rolls are rotated out of the small end of the
notches so that the pinion collar and clutch
shell are no longer locked together, consequently
the high speed of the pinion is not transmitted
to the armature shaft.
SPRING
PLUNGER
ROlLER
[
PINIO N AND COLLA
~
.
- - ,
"'-""\L,_A _S
_SEMBLY
((I/:
.-
~
I~~~~
\('
O !
~
SECTION THROUGH
OVERRUNNING CLUTCH
Figure 10-S4-Cranking Motor Drive A..embly, Sectional View.
Advertisement
