Air Brake Manual
Air Brake Manual
Air Brake Manual
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· At 90 psi or above, release the spring parking<br />
brakes to prevent compounding the brake<br />
pressure and charge the trailer system by opening<br />
the trailer supply valve. Apply and release the<br />
trailer brakes to ensure they are releasing.<br />
(Failure to release could indicate supply<br />
(emergency) and control (service) lines are<br />
crossed).<br />
· Continue building reservoir air pressure. Check<br />
that the governor places the compressor in the<br />
unloading stage between 115 psi minimum and<br />
135 psi 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 (the<br />
reading on the air gauge should increase).<br />
· Continue fanning the brake pedal. Warning<br />
device(s) must operate at or before 55 psi and the<br />
trailer supply valve will close at or before 20 psi.<br />
Continue fanning the brake pedal, the spring<br />
parking brake should also apply at or before the<br />
reservoir pressure drops to 20 psi.<br />
· Rebuild reservoir air pressure at fast idle to<br />
between 115 psi minimum and 135 psi maximum.<br />
At 90 psi charge the trailer system by opening the<br />
trailer supply valve.<br />
· Set the tractor spring parking brake (if possible).<br />
Tractor and Trailer Emergency System Check<br />
· Disconnect supply (emergency) line glad hand.<br />
· Trailer brakes should apply immediately.<br />
· There should be no air loss from trailer glad hand.<br />
· <strong>Air</strong> from the tractor should:<br />
(a) stop immediately or,<br />
(b) bleed down no lower than 20 psi and stop.<br />
Note: Under no circumstances should the tractor<br />
pressure drain below 20 psi.<br />
· Reconnect supply (emergency) line and charge<br />
trailer. Rebuild pressure if necessary.<br />
Tractor Protection Valve Check<br />
· Disconnect control (service) line glad hand.<br />
· No air should escape from the tractor or trailer glad<br />
hands.<br />
· Release the spring parking brake.<br />
· Make full brake application. Tractor brakes will<br />
function normally. Trailer service brakes will not<br />
function at all. With brake application maintained, air<br />
will continue to escape from the control (service)<br />
line until air pressure in the reservoirs is depleted to<br />
no lower than 20 psi. The trailer supply and the<br />
tractor protection valve will close and the tractor<br />
and trailer brakes will apply. <strong>Air</strong> loss from control<br />
(service) line will stop.<br />
· Reconnect control (service) line.<br />
Check for Leakage<br />
· Rebuild reservoir air pressure at fast idle to between<br />
115 psi minimum and 135 psi maximum, release the<br />
spring parking brake and charge the trailer at<br />
90 psi.<br />
· Shut off the engine.<br />
· Make a full brake application with the foot valve and<br />
hold. Observe the reservoir air pressure gauge.<br />
· The reading should not drop more than 4 psi per<br />
minute. Lightly tap the gauge to ensure it is not<br />
sticking. For an accurate reading brake application<br />
should be held for at least two minutes.<br />
· Listen for audible air leaks.<br />
· Release full brake application.<br />
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