freightliner cascadia Driver Manual page 191

Pre- and Post-Trip Inspections and Maintenance
2.2 Turn the ignition to the ON position. The
ICU will complete a full gauge sweep and
bulb check, and an audible warning will
sound. Ensure the low air pressure lamp
(BRAKE AIR) remains illuminated and an
audible warning continues to sound after
the gauge sweep is complete.
3.
Check air governor cut-in and cut-out pressures.
3.1 Start the engine and ensure the BRAKE
AIR lamp goes out and the buzzer si-
lences when pressure reaches approxi-
mately 70 psi (483 kPa) in both air reser-
voirs.
The air governor should cut out at ap-
proximately 120 psi (827 kPa). For ve-
hicles with an optional dryer reservoir
module (DRM), the cut-out pressure is
approximately 130 psi (896 kPa).
3.2
With the engine idling, apply the brake
pedal several times. The air governor
should cut in when pressure in the primary
air reservoir (top air gauge) reaches ap-
proximately 100 psi (689 kPa).
4. Check air pressure build-up time.
4.1 With the air system fully charged, make
one full brake application and note the air
pressure reading on the primary air
gauge.
4.2 Further reduce air pressure using moder-
ate brake applications, then run the en-
gine at governed rpm.
4.3
Note the time that the pressure reaches
the previously noted reading on the pri-
mary air gauge, then note the time that
the air pressure reaches cut-out pressure.
4.4 If it takes longer than 30 seconds to reach
cut-out pressure after the primary air
gauge passes the previously noted pres-
sure (noted after one full brake applica-
tion), eliminate any leaks or replace the air
compressor before operating the vehicle.
5. Check air leakage in the system.
5.1 With the parking brake applied, the trans-
mission out of gear, and the air system
fully charged, release the service brakes
and shut down the engine.
5.2 Wait one minute and note the air pressure
drop in psi (kPa) per minute from the pri-
mary air reservoir.
If the pressure drop exceeds the limits
shown in Table
before operating the vehicle.
6. Check the air pressure reserve.
With the engine still off, make one full brake ap-
plication and observe the pressure drop on the
primary air gauge. If pressure drops more than
25 psi (172 kPa), eliminate any leaks before op-
erating the vehicle.
Maximum Allowable Air Leakage
Description
Truck or Tractor Only
Truck or Tractor w/Single Trailer
Truck or Tractor w/Two Trailers
Table 21.1, Maximum Allowable Air Leakage
WARNING
When cleaning windshields and windows, always
stand on the ground or on a secure ladder or
platform. Use a long-handled window cleaner. Do
not use the cab steps, tires, fenders, fuel tanks,
engine, or under-hood components to access the
windshield or windows. Doing so could cause a
fall and result in an injury.
7. Inspect the mirrors, window glass, and wind-
shield for cracks or other damage.
8.
Ensure that the horn, windshield wipers, and
windshield washers are operating properly.
These devices must be in good working order for
safe vehicle operation.
9. Ensure the heater and defroster are operating
properly.
10. Check the operation of all interior lights.
10.1 Turn on the headlights and leave them on.
Ensure all equipped gauge bulbs illumi-
nate in the dash message center.
10.2 Ensure all equipped driver control
switches illuminate.
21.1, eliminate any leaks
Pressure Drop:
psi (kPa) Per Minute
Released Applied
2 (14) 3 (21)
3 (21) 4 (28)
5 (35) 6 (42)
21.6