Chevrolet 70 1969 Series, Shop Manual

Page: 632 / 913

POWER BRAKE 5-23
1 2 3
Emergency Line
Outlet Port
(To Trailer)
Service Line
Outlet Port
(To Trailer)
Control Port
(From Emergency
Air Valve)
Emergency Line
Inlet Port
(From Air Tank)
Service Line Inlet
Port (From Double
Check Valve)
Control End Cover
End Cover Gasket
Valve Body
Control Plunger Seal
Control Plunger
Valve Plunger
7 Plunger Spring
8 End Cover Gasket
9 Service Line End
Cover
10 Plunger O-ring Seals
11 Exhaust Check Valve
TPM-7559
F igure 2 6 — Trailer B r e a k a w a y V a lv e -T ilt C a b
ASSEMBLY
1. Insert exhaust valve assem bly in tractor protection
valve body.
2. Insert exhaust valve spring in valve body.
3. Install two O-rings on plastic valve spool.
4. Install plastic valve spool in valve body.
5. Install inlet valve spring and inlet valve disc in end
cap. Install O-ring on end cap.
6. Place end cap assembly in position on valve body and
secure with four screws and lock washers.
7. Install piston return spring in valve body.
8. Install block vee and O-ring on piston. Install piston
assembly in valve body.
9. Install O-ring and plastic piston stop in valve body.
10. Install snap ring in valve body.
BREAKAW AY VALVE (Fig. 26)
(TILT CAB MODELS)
DISASSEMBLY
1. Rem ove four screw and washer assemblies from con­
trol end cover. Separate end cover and body and dis­
card gasket. Pull control plunger out of bore. Remove
and discard seal cup and O-ring seals.
2. Rem ove four screw and w asher assemblies from serv­
ice line end cover. Separate end cover and body and
discard gasket. Pull plunger spring and valve plunger
out of bore. Rem ove and discard plunger O-rings.
3. Remove exhaust check valve end cap, spring, and
ball.
C lean in g, Inspection, an d Repair
W ash all m etal parts in mineral spirits. Dry thoroughly.
Exam ine body and end covers for cracks or other signs of
dam age. Inspect plunger surfaces and bores in valve body.
Remove slight scratches or scores with crocus cloth. In­
spect plunger spring and replace if dam aged or broken.
NOTE: Keep all parts dirt a n d dust free.
ASSEMBLY
1. C oat plungers and body bore with a m ultipurpose
grease (N .L .G .I. num ber 1 with a rust inhibitor ingre­
dient). Carefully install new seal cup and O-ring seals
in grooves of control plunger. Lip of seal cup should
point in a direction aw ay from O-ring. Insert plunger,
small end first, in “ C O N T R O L ” end of valve.
2. Place new gasket over pilot on control end cover.
W ith gasket properly aligned, insert cover pilot in
“ C O N T R O L ” end of valve. Install four screw and
washer assemblies in end cover and body. Tighten
firmly.
3. Carefully install new O-ring seals in the grooves of
valve plunger. There are three sizes of O-rings on this
plunger. Each O-ring should be in groove of right
size. Insert plunger, small end first, in “ S E R V IC E "
end of valve. Insert plunger spring.
4. Place new gasket over pilot on service line end cover.
W ith gasket properly aligned, insert cover pilot in
“ S E R V IC E ” end of valve. Install four screw and
washer assemblies in end cover and body. Tighten
firmly.
5. Insert exhaust check valve ball and spring in exhaust
port. Install end cap and stake securely in two places.
9
10
11
18
Cap Screw
Diaphragm Washer
Exhaust Diaphragm
Retainer Ring
Valve Body
Piston
Control Port
Piston Grommet
(Small)
Lock Washer
Mounting Nut
Cap Nut
T
16
15
14 13
12 Supply Port
Seal Ring
Inlet and Exhaust
Valve Spring
Inlet and Exhaust
Valve
Delivery Port
Control Port
Piston Springs
Piston Grommet
(Large)
Cover Plate nm
13
14
15
16
17
18
19
20
Figure 2 7 — In v ersion V a lv e A sse m b ly
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SHO P M A N UA L