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Inflation Rate Test:
This will test how long it takes the air system
to achieve a specific pressure in a timed event
when starting at a lower pressure. This test
will verify the minimum acceptable volume of
compressed air created by the air system.
Start engine. Increase engine speed to
1000 rpm.
Beginning time for the test will
commence when air system pressure
obtains 85 psi.
End time when system pressure obtains
100 psi.
Elapsed time must not exceed 45 seconds.
Air Governor Cutout Test:
The air governor controls action of the air
system pump. This will test the air governor
cutout pressure setting, which indicates system
pressure has achieved maximum set psi.
Start engine.
Run engine until a chuff (air release) is
heard from the air dryer.
Maximum cutout pressure must not exceed
155 psi. Air system pressure will stabilize
between 135 to 145 psi.
Unapplied Pressure Loss Test:
This test will verify maximum acceptable
air system pressure loss rate without use of
any pneumatically operated devices. This test
requires a flat, level surface as the park brake
will be released with the engine off. Chock
wheels to prevent vehicle movement.
Start engine.
Run engine until a chuff (air release) is
heard from the air dryer.
Shut engine off.
Release the park brake.
Note system pressure after air system
stabilizes from release of park brake. Air system
pressure must not lose more than 2 psi per
minute.
Applied Pressure Loss Test:
This test will verify the rate of maximum
acceptable air system pressure loss with only
the service brakes applied. DO NOT use
other pneumatically operated devices during
this test. This test requires a flat, level surface
as the park brake will be released with the
engine off. Chock wheels to prevent vehicle
movement.
Start engine.
Run engine until a chuff (air release) is
heard from the air dryer.
Shut engine off.
Release the park brake.
Apply and hold service brake pedal.
Note system pressure after air system
pressure stabilizes. Air system pressure must
not lose more than 3 psi per minute.
Low Air Warning Test:
This test will verify low air warning buzzer/
lamp activation. A Low Air warning buzzer or
lamp will sound/illuminate should air system
pressure fall to 60 or 65 psi.
Start engine.
Run engine until low air warning
indicators are inactive.
Shut engine off then turn key to
ignition on.
Fan (apply/release in quick succession)
service brake pedal.
Low air warning indicator will sound no
lower than 60 psi.
Park Brake Apply Test:
The park brake will automatically apply if
low air warning indicator(s) are ignored and
system pressure falls well below safe operating
levels. A flat, level surface is required as the
park brake will be released with the engine off.
Chock wheels to prevent vehicle movement.
Start engine.
Run engine until low air warning
indicators are inactive.
Shut engine off.
Release park brake.
Fan (apply/release in quick succession)
service brake pedal.
The park brake will automatically apply
between 20 to 40 psi.
Park Brake Hold Test:
This test will verify engagement of the park
brake. A flat, level surface is required. While
the test is performed with the park brake
applied, use precautions in case of vehicle
movement. This test only verifies the park
brake is engaged. It is not intended to verify
the maximum amount of braking force created
by the park brake.
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