Chevrolet 10 Series 1968, Service Manual

Page: 301 / 713

BRAKES 5-58
STANDARD AIR BRAKES
GENERAL DESCRIPTION
The air brake system (fig. 91) completely replaces all
hydraulic brake components with air brake parts for pro­
ducing and utilizing greater braking forces. The air
compressor in the all air brake system builds up and
maintains the air pressure required to operate all of the
air powered devices.
A pressure protection valve is installed between the
primary air brake system and the auxiliary air operated
accessories. A minimum air pressure of approximately
80 psi is required to lift the valve diaphragm off its seat
and permit air to pass to the accessories. Should the air
pressure drop below 80 psi, the diaphragm closes off all
air to the accessories and all remaining air pressure is
reserved for the brake system.
MAINTENANCE AND ADJUSTMENTS
COMPRESSOR
The Tu-Flo 400 and 500 compressors are single stage
reciprocating piston type compressors. Both the 400 and
500 compressors have two cylinders.
35,000 Miles:
Remove compressor discharge valve cap nuts and check
for presence of excessive carbon deposits. Also, check
the discharge line for carbon. If excessive carbon is
found in either check, the cylinder head or discharge line
should be cleaned or replaced.
100,000 Miles:
Depending upon operating conditions and experience,
disassemble compressor, clean and inspect all parts
thoroughly. Repair or replace all worn or damaged
parts.
IMPORTANT:
Should it be necessary to drain
the engine cooling system to prevent damage
from freezing, water cooled compressors must
be drained as both cylinder block and cylinder
head are water cooled. Use drain cock or re ­
move head and/or block pipe plugs.
1. S la ck Adjuster
7. Em ergency/Parking
2. Standard Brake Chamber
"P ush -Pu ll" V a lv e
3. Lim iting and Q u ic k Release
8. Trailer Brake Hand
V a lv e
Control V a lv e
4. A ir Compressor
9. Tw o-W ay V a lv e
5. A ir Intake
10. Low A ir Buzzer Switch
6. Governor
11. A ir G auge
12. A p p lica tio n V a lv e 18. Relay V a lv e
13. Double C h eck V a lv e 19. Stopmaster Brake
14. Tractor Protection V a lv e Chambers
15. Trailer Brake Service Line 20. C h e ck V a lv e
16. Trailer Brake Emergency 21. Moisture Ejector V a lv e
Line
22. Drain V a lve
17. A ir Tanks 23. Safety V a lv e
F ig . 91-Schem atic Diagram of T yp ica l A ir Brake System
CHEVROLET TRUCK SERVICE MANUAL