SECTION 12: BRAKE AND AIR SYSTEM
24
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Final Version – Rev.2 April 2016)
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 gauge
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, coat all air
line connections and pneumatic 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 gauge 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 and foot
brake applied, coat all air line connections
and brake pneumatic 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.
IMPORTANT NOTE
To maintain your vehicle’s air disc brakes at
their original performance standard, we
strongly recommend use of only genuine,
approved service replacement parts on Bendix
and Knorr-Bremse air disc brake systems.
If non-approved friction materials or
replacement components are used, neither
Prevost Car nor Bendix Spicer Foundation
Brake LLC will accept any air disc brake-
related warranty returns or claims.
For more information on this policy, refer to
Bendix-Prevost product notification.
28. BRAKE AIR
CHAMBER
This vehicle is equipped with
Knorr-Bremse
SN7000
disc brakes on all axles, it also uses
“Knorr-Bremse” brake chambers. 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. Refer to
Figure 38 and Figure 39. The front and tag axle
brake air chambers are used only for service
brake duty.
FIGURE 38: FRONT AXLE BRAKE AIR CHAMBER
12158
28.1 MAINTENANCE
Every 6,250 Miles (10 000 km) or twice a year,
whichever comes first depending on type of
operation:
FIGURE 39: DRIVE AXLE BRAKE AIR CHAMBER
12126
