Chevrolet 70 1969 Series, Shop Manual

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BRAKES 5B-69
AIR P R ESSU R E A B O V E N O R M A L
P R O B A B L E CAUSE R E M E D Y
1. Defective air gauge
1. Replace
2. Governor out of adjustment or defective 2. Adjust, repair or replace
3. Restricted line between governor and com­
pressor
3. Clear line or replace
4. Compressor unloader inoperative 4. Repair or replace
Q U IC K LOSS O F P R E SSU R E W H E N EN G IN E
IS S T O P P E D
(B R A K E S N O T A P P L I E D )
P R O B A B L E CAUSE R E M E D Y
1. Leaking lines or connections
1. Repair or replace
2. Worn or leaking compressor exhaust valve or
one-way check valve.
2. Repair or replace
3. Leaking governor
3. Repair or replace
4. Leaking application valve
4.
Repair or replace
5. Open or leaking reservoir drain cock 5. Close, repair or replace
(BRAKES F U L L Y APPLIED)
1. Leaking brake chamber
1. Repair or replace
2. Leaking application valve
2. Repair or replace
3. Leaking service line 3. Repair or replace
4. Leaking chamber hoses
4. Repair or replace
5. Dirt in two-way check valve. (If equipped with
hand control valve and brakes are applied by
the foot valve, dirt in the two-way check valve
could cause a pressure leak at the hand valve
exhaust port.)
5. Clean or replace
6. Defective quick release valve
6. Clean or replace diaphragm.
S A F E T Y V A L V E “ B L O W S O F F ”
P R O B A B L E C A U SE
R E M E D Y
1. Safety valve out of adjustment 1. Adjust
2. Pressure in system above normal 2.
See chart on "A i r pressure above normal”
3. Governor out of adjustment
3. Adjust
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SHOP M ANUA L