Air Brake Manual
Air Brake Manual
Air Brake Manual
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Compressor and Warning Devices Check<br />
· Start the engine and run at fast idle to build air<br />
pressure.<br />
· Warning device(s) must operate to 55 psi or higher.<br />
· Ensure reservoir pressure builds from 50 to 90 psi<br />
within three minutes.<br />
· If equipped with spring parking brakes release them<br />
to prevent compounding the brake pressure.<br />
· Continue building reservoir air pressure. Check that<br />
the governor places the compressor in the unloading<br />
stage between 115 psi minimum and 135 psi<br />
maximum.<br />
· Fan the brake pedal until the pressure drops to<br />
80 psi; stop fanning to see if the governor has<br />
placed the compressor in the loading stage (needle<br />
on the air gauge should start to climb).<br />
· Continue fanning the brake pedal. Warning<br />
device(s) must operate at or before 55 psi.<br />
Check for Leakage<br />
· Rebuild reservoir air pressure to between 115 psi<br />
minimum and 135 psi maximum (if equipped release<br />
the spring parking brakes).<br />
· Shut off the engine.<br />
· Make a full brake application with the foot valve<br />
and hold. Observe the reservoir air pressure gauge.<br />
· The reading should not drop more than 3 psi per<br />
minute. Lightly tap the gauge to ensure it is not<br />
sticking. For an accurate reading application should<br />
be held for at least two minutes.<br />
· Listen for audible air leaks.<br />
· Release full brake application.<br />
<strong>Brake</strong> Test<br />
· Reapply the parking brake, remove wheel blocks.<br />
· Gently tug against the parking brakes in low gear,<br />
it should hold the vehicle.<br />
· Release the parking brakes.<br />
· Move vehicle ahead slowly and make a service<br />
brake application to check brake response.<br />
Section Summary Questions<br />
1. What is the maximum time permitted for the<br />
compressor to build from 50 to 90 psi<br />
2. What is the maximum air pressure loss<br />
permitted on a full brake application with the<br />
motor shut off<br />
3. How can the holding power of the trailer brakes<br />
be tested<br />
4. What is the final brake test that should be made<br />
before the vehicle is put into service<br />
5. Is a brake adjustment part of the air brake test<br />
given by the Division of Driver and Vehicle<br />
Licencing<br />
76
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