Brake Air Chamber; Maintenance - PREVOST H3-41 Maintenance Manual

SECTION 12: BRAKE AND AIR SYSTEM
CONDITION: Full pressure, engine stopped,
parking brake applied
1. Allow at least 1 minute for pressure to
stabilize.
2. Stop engine, then check air pressure gage
for 2 minutes. Note any pressure drop.
3. Pressure should not drop by more than 3 psi
(20 kPa) per minute.
For common corrections, refer to the following
check list:
Excessive air loss:
• With the primary air system at normal
operating pressure 122-140 psi (841- 965
kPa), coat all air line connections and pneu-
matic components with a water and soap
solution. Bubbles will indicate an air leak,
and none should be permissible. Repair or
replace defective parts.
• Listen for leaks and correct as required.
• Redo test to check all items repaired or
replaced.
Brake System Air Leakage
CONDITION: Full pressure, engine stopped,
parking brake released.
1. Apply service (foot) brakes, allow at least 1
minute for pressure to stabilize.
2. Hold down foot valve for 1 minute while
observing air pressure gage on the dash-
board.
3. Pressure drop should not be more than 3 psi
(20 kPa) per minute.
For common corrections, refer to the following
check list.
Excessive leakage on brake service side:
• With the primary air system at normal
operating pressure 122-140 psi (841- 965
kPa) and foot brake applied, coat all air line
connections and brake pneumatic compo-
nents with a water and soap solution. Bub-
bles will indicate an air leak, and none should
be permissible. Repair or replace defective
parts.
• Listen for leaks and correct as required.
• Redo test to check all items repaired or
replaced.
42 PA1621 Maintenance Manual All Series | Revised June 2020

21. BRAKE AIR CHAMBER

This vehicle uses
chambers on all axles. The drive axle chambers
consist of two separate air chambers, each
having its own diaphragm and push rod. They
are used as a service brake chamber, an
emergency brake in case of air pressure loss
and a spring-applied parking brake.
.
FIGURE 32
FIGURE 47: DRIVE AXLE BRAKE AIR CHAMBER
The front and tag axle brake air chambers are
used only for service brake duty (FIGURE 33).
FIGURE 48: FRONT AND TAG AXLE BRAKE AIR
CHAMBER
21.1

MAINTENANCE

Every 6,250 Miles (10 000 km) or twice a year,
whichever comes first depending on type of
operation:
Check all hoses and lines. They should be
secure and in good condition.
"Knorr-Bremse" brake
Refer to