Chevrolet 10 Series 1968, Руководство по обслуживанию

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BRAKES 5-84
7. Connect an air supply (shop air) line to the locking
port. By hand press down on the actuator non­
pressure plate and at the same time apply air to
the locking port. As the shaft is unlocked, ease the
non-pressure plate back and remove push plate and
shaft assembly with push rod and return spring.
8. Hold lock cap down against roller spring tension
and completely remove all four (4) cap screws be­
fore releasing and removing cap.
9. Remove roller spring and spring seat washer.
10. Remove all eight (8) rollers.
11. Next cautiously apply air at the locking port to as­
sist in removal of collar and piston, and to remove
piston grommet.
12. Inspect bearing in shaft bore of non-pressure and
remove it only if it is showing signs of wear and is
to be replaced.
13. The push rod should not be removed from the shaft
unless it is damaged. If the rod is removed it must
be replaced. To remove the rod, place a heavy
washer over the rod against the shaft, then position
a spacer and second washer over the rod and be­
neath the yoke locknut. Turn the locknut down with
a long handled wrench, pulling the push rod from
the shaft.
14. The knurled T-bolts in the non-pressure plate can be
removed and replaced if damaged.
Cleaning and Inspection
1. Wash all metal parts in a good cleaning solvent and
dry. Any reusable rubber parts should be wiped
clean.
2. Discard felt breather.
3. Inspect all parts for excessive wear or deterioration.
4. Particular attention should be given to the piston
and collar bores in the plate. Also, the air passage
from the lock port to piston bore should be clean
and not restricted. It may be necessary to remove
the inspection plug to thoroughly clean this passage.
5. Rollers should be checked carefully and all replaced
if one or more need replacing.
6. Check springs for cracks, distortion or corrosion.
7. Replace all parts not considered serviceable during
these inspections, especially rubber parts.
Assem bly
NOTE: On assembly, line up parts as they were
marked prior to disassembly. If the bearing in
the non-pressure plate was removed it should
be re-installed or replaced.
1. Lubricate piston and collar bores, shaft, piston
grommet, piston and roller cavity with a barium
base lubricant.
2. Position piston grommet in piston bore, then piston
with smooth end down against grommet.
3. Place collar in its bore in plate.
4. Position all eight (8) rollers in groove formed by top
of piston and collar ramp.
5. Place roller spring seat washer on top rollers.
6. Position cone shaped roller spring on washer with
small end to washer.
7. Position cap on roller spring. Press cap down and
hold while installing cap screws evenly and securely.
8. Turn over non-pressure plate with lock mechanism
installed and position return spring in plate with
large end down.
9. Position push plate and shaft over return spring and
press down so shaft moves through lock. The lock
should hold shaft position against return spring. If
not, check assembly to this point.
10. Install service diaphragm, service pressure plate
and clamping ring.
11. Install auxiliary diaphragm, auxiliary pressure plate
and clamping ring.
12. Tighten clamping ring bolts in both clamping rings
evenly and securely.
13. Install boot and new breather felt, then splash guard
down over boot.
Installation
NOTE: The Safety Actuators must be installed
with the drain slot pointing down and towards
the center line of the vehicle.
1. Mount Actuator to mounting bracket and tighten
securely.
2. Fasten actuator push rod yoke to slack adjuster with
yoke pin. Lock yoke pin with cotter pin.
NOTE: The angle formed by the push rod and
slack adjuster arm should be greater than 90°.
3. Connect air lines to actuator. Take care that the
correct line is installed in the correct port.
4. Adjust brakes.
5. Perform "Operating and Leakage Checks" as out­
lined in this section.
STOPMASTER BRAKES
The Stopmaster type brake differs from the conven­
tional "S" cam type brake in several respects. The air
chamber push rod is connected to the brake shoes through
a series of wedges, rollers, and plungers rather than
through a slack adjuster and camshaft. Stopmaster
brakes are used at the rear wheels only. Stopmaster
brakes employ two different type air chambers; (1) a
standard air chamber which is operated by air pressure
and (2) a "Fail-Safe" air chamber which can be operated
either by air pressure or by spring pressure. There
are three basic variations of Stopmaster brakes shown in
Figure 120.
AUTOMATIC ADJUSTER
All Stopmaster brakes have automatic adjuster mech­
anisms. The basic part of the adjuster (refer to fig.
121) is a plunger assembly which is made up of the
adjusting plunger, the actuator, and the adjusting bolt.
The actuator is threaded internally to receive adjusting
bolt. On the external surface, there are buttress type
teeth. The plunger guide is free to slide in a drilled
hole in the spider housing and has teeth to match those on
the exterior surface of the actuator. A spring, gasket,
and bolt are used to hold the guide in contact with the
actuator.
CHEVROLET TRUCK SERVICE MANUAL