Chevrolet 70 1969 Series, Shop Manual

Page: 240 / 913

BRAKES 5B-47
umn. The valve has a black knob which moves in
and out ("push-pull") for operation. The lettering
on the knob is illustrated in figure 18. A red color­
ed ring on the knob, when exposed, indicates that
parking brake is on. The valve has four ports; two
delivery, one supply and one for connection to the
service brake foot control valve. The push-pull
valve directs the flow of air to the D D 3 brake ac­
tuator through the inversion valve. The direction
of flow is controlled within the valve by a combin­
ation inlet and exhaust valve in conjunction with
the position of the knob ("push"for service, - "pull"
for parking).
CONTROL VALVE OPERATION
For operation of the push-pull control valve,
refer to figure 17 and the description given previ­
ously under "Service Brake Operation,” "Parking
Operation" and "Emergency Operation."
CONTROL VALVE REPLACEMENT
R E M O V A L
1. Secure vehicle by some means other than
air brakes.
Figure 18— DD3 Control Valve Knob
2. Exhaust air from parking brake system. It
is unnecessary to exhaust service air.
3. Disconnect air lines from push-pull con­
trol valve. Mark lines to assure installation in
correct valv ports when replacing valve.
4. Drive spirol pin out of button and remove
button.
5. Remove mounting nut from valve body and
remove valve from dash panel.
IN S T A L L A T IO N
1. Position valve on dash panel and secure
with mounting nut.
1 Lock Ring
2 Spacer
3 Slack Adjuster
4 Camshaft Seal
5 Camshaft Bushing
J O
/ I T
/12
,13
-14
/15
-16
6 Camshaft and Brake
Chamber Bracket
7 Backing Plate
8 Cam (integral with shaft)
9 C am Roller
10 Brake Shoe
11 Brake Shoe Return Spring
12 Guide Pin Washer
13 Guide Pin " C " Washer
14 Guide Pin
15 Lock Ring
16 Anchor Pin
t
-1584
Figure 19— Front Brake Assembly IWagner)
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L