Chevrolet 70 1969 Series, Shop Manual

Page: 218 / 913

BRAKES 5B-25
SECTION 5B
AIR BRAKES
BRAKE SYSTEM EQUIPMENT
The air brake system comprises a group of
devices, some of which maintain a supply of com ­
pressed air, some of which direct and control the
flow of the compressed air, and others which trans­
form the energy of compressed air into the mech­
anical force and motion necessary to apply the
brakes. Refer to figure 1 for typical schematic
diagram.
Information in this section covers all stand­
ard air brake equipment, as well as other units
which are used as optional equipment on some
models.
There are two basically different types of air
actuated brakes used on vehicles covered by this
manual. One is the cam-type brake which is ener­
gized by an air chamber and slack adjuster ar­
rangement. The other is called Stopmaster, which
is a complete assembly consisting of two air cham­
bers connected to two brake shoes through tubes
containing push-rod and plunger assemblies. All
information relative to Stopmaster brakes is found
under the heading of "Stopmaster Brakes" in this
section. Unless otherwise specified, all pedals,
valves* controls, etc., covered in this manual
apply to both cam-type and Stopmaster type brake
systems.
BRAKE SYSTEM MAINTENANCE
Normal operation of braking system necessi­
tates periodic tests, inspection, and adjustments to
assure safe, efficient operation. Test, inspection
and adjustment procedures for each air brake con­
trol unit are described under individual headings
in this section. Since the vehicles covered by this
Maintenance Manual will be used in a wide variety
of operation types, it is impossible to fix mainten­
ance intervals (either time or mileage) which will
satisfactorily suit all conditions. Therefore, any
such intervals stated in these maintenance pro­
cedures must be related to the type of usage to
which a particular vehicle is put. Obviously, atruck
CONSTANT PRESSURE LINES
DELIVERY LINES
1 Slack Adjuster
2 Standard Brake Chamber
3 Limiting and Quick Release
Valve
4 Air Compressor
5 Air Intake
6 Governor
T
22 20
Emergency/Parking
"Push-Pull” Valve
Trailer Brake Hand
Control Valve
Two-Way Valve
Low Air Buzzer Switch
11 Air Gauge
12 Application Valve
13 Double Check Valve
14 Tractor Protection Valve
15 Trailer Brake Service Line
16 Trailer Brake Emergency
Line
17 Air Tanks
18 Relay Valve
19 Stopmaster Brake
Chambers
20 Check Valve
21 Moisture Ejector Valve
22 Drain Valve
23 Safety Valve T .2344
Figure 1— Schematic Diagram of Typical Air Brake System
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK SH O P M A N U A L