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 23.1, eliminate any leaks
before operating the vehicle.
Maximum Allowable Air Leakage
Description
Pressure Drop:
psi (kPa) Per Minute
Released Applied
Truck or Tractor Only 2 (14) 3 (21)
Truck or Tractor w/Single Trailer 3 (21) 4 (28)
Truck or Tractor w/Two Trailers 5 (34) 6 (41)
Table 23.1, Maximum Allowable Air Leakage
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.
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.
10.3
Ensure both turn signal indicator bulbs
illuminate in the dash message center
when the turn signal switch is activated.
11.
Check the operation of all exterior lights. See
Fig. 23.8.
1
1
2
2
3
4
5
5
6
05/04/2012 f545896
1. Fog Light
2. Headlight
3. Front Turn Signal
4. Sidewall Turn Signal
5. Clearance Light
6. Marker Lights
Fig. 23.8, Exterior Lights
Pre- and Post-Trip Inspections and Maintenance
23.6
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