Chevrolet 70 1969 Series, Руководство по ремонту

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ENGINE ELECTRICAL 6Y-7
STARTING SYSTEM
GENERAL DESCRIPTION
Overrunning clutch type starting motors hav­
ing an enclosed shift lever are used on all vehicles
covered by this manual.
The drive end housing is extended to enclose
entire shift lever mechanism and solenoid plunger.
The solenoid flange is mounted on drive end hous­
ing with sealing compound used between the flange
and filed frame. A compression type shift lever
return spring located inside the solenoid case is
used to operate the overrunning clutch. On gasoline
engine models, primary circuit to ignition coil is
fed from solenoid while starter is operating.
Positive lubrication is provided to bronze
bushings in commutator end frame, in the drive
end housing, and in the nose housing by oil satur­
ated wicks that project through each bushing and
contact the armature shaft.
STARTING SYSTEM OPERATION
The starting system consists of the battery,
starting motor, including the drive assembly which
engages the flywheel ring gear during cranking, the
starter solenoid, mounted on the starting motor
for shifting the drive assembly and closing the
motor circuit, and the ignition or control switch
which connect a lead from the battery to the sole­
noid switch, when in the start position. During
cranking, the ignition switch (gasoline engine
models) also, connects the battery to the coil.
When starter circuit is energized, the solenoid
operated shift lever slides the pinion into mesh
with the flywheel ring gear teeth. The rotary mo­
tion between pinion and ring gear, provided by
spiral splines on clutch shaft, normally relieves
tooth abutment on the first attempt to engage pin­
ion and ring gear. A protective sleeve located on
the spiral spline acts as a stop for the pinion when
extreme tooth abutment occurs. This limits the
clutch travel, preventing switch contacts in the
solenoid from closing. Therefore, the armature
cannot rotate before pinion is engaged properly,
preventing damage to pinion and ring gear. A sec­
ond attempt to engage rotates pinion enough to as­
sure proper engagement.
STARTING MOTOR CIRCUIT TESTS
(ON VEHICLE)
Although the starter cannot be checked against
specifications on the vehicle, checks can be made
for excessive resistance in the starter circuit.
N O T E : To make these checks on gasoline
engine models, disconnect the primary lead at the
distributor to prevent engine starting. On Diesel
models, pull stop knob on instrument panel out to
set the injector racks in no-fuel position to prevent
engine starting.
Referring to figure 1 and with starter crank­
ing engine during each check, measure resistance
in various parts of the circuit as follows:
V-l - Check V-l with voltmeter leads connected
to battery positive (+) post and the battery
terminal on the starter solenoid. On vehicles
equipped with a solenoid and a magnetic
switch, connect voltmeter leads as noted
above, then connect voltmeter leads to bat­
tery positive (+) post and the battery term­
inal on the magnetic switch.
V-2 - Check V-2 with voltmeter leads connected
to battery terminal and to motor terminal
on solenoid. On vehicles equipped with a
solenoid and a magnetic switch, connect
voltmeter leads as noted previously, then
connect voltmeter leads to battery terminal
and to motor terminal on magnetic switcn.
V-3 - Check V-3 with voltmeter leads connected
to battery negative (-) post and the starter
field frame.
V-4 - On vehicles equipped with a solenoid and a
magnetic switch, check V-4 with voltmeter
leads connected to motor terminal on mag­
netic switch and to positive terminal (+) on
starter solenoid.
Figure 1 — Voltmeter Connections For Checking Circuits
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L