Air Break Test Flashcards
Drop wheel chocks
Both sides of rear tire
Turn on battery and ignition switches
Verity gauge sweep and air system warning signals
Verify the parking break is applied
Air Protection Valve (APV) should be pulled in the out position.
No air is charging the break chamber.
Release the parking break by pushing in APV on dash.
Engine should glide into wheel chocks. Allow air tanks to settle.
Observe the air gauges for 60 seconds for air loss.
Straight Truck: <3 psi in 60 seconds
Tractor Trailer: <4 psi in 60 seconds
Apply steady pressure to break pedal allow tanks to settle and continue for 60 seconds.
Observe gauges for air loss for 60 seconds.
Straight Truck: <3 psi in 60 seconds
Tractor Trailer: <4 psi in 60 seconds
Fan the breaks
Observe audible and visual low air alarms activation.
Low air audible alarm should sound between 90-60 psi.
Continue Fanning breaks until APV pops automatically.
APV should activate between 40 - 20 psi. Failure of APV to pop before reaching 20 psi will result in air break test failure.
Failure to stop fanning breaks once APV pops will be automatic failure of student as damage to system may occur.
Start Engine motor and place in high idle to 1200 rpms.
Pressure gauges must go from 50 - 90 psi in <3 minutes at 1200 rpms. Air compressor must cut out before 135 psi to meet DOT standards
NFPA 1911 requires air pressure to go from 0 to serviceable pressure (>90 psi) in less than 60 seconds.
Unit ready for service
Verify all gauges have reached working pressure. Shut down motor. Stow wheel chocks.
C: cut-in pressure
Compressor should engage at 100 psi.
Compressors that do not engage prior to 95 psi merit a service defect report.
Compressors that do not engage prior to 80 psi meets OOS criteria.
O: cut-out pressure
Compressors should disengage at 120-135 psi.
Compressors that do not disengage prior to 135 psi meet OOS criteria
L: low pressure warning
Audible and visual warning devices must activate between 90-60 psi
Warnings that activate below 60 psi merit a service defect report.
A: air leakage
Straight Truck: <3 psi in 60 seconds
Tractor Trailer: <4 psi in 60 seconds