3B. Close Hood - Air Break Test Flashcards
In Cab - Air Brakes
How do you perform a air leakage test?
Wait until the air system is fully charged (120-140 PSI range)
Place the truck in neutral
Turn off the engine
Turn key on but do not start truck
Push in both parking brakes
Fully apply the foot brake
wait until after the initial pressure drops
Start timer
It should not lose more than 4 PSI in one minute in a combination vehicle.
In Cab - Air Brakes
How do you perform a low pressure warning test?
After the air leakage test…
Pump the brakes
The low pressure warning light & buzzer should come on at or before it reaches 60 PSI.
In Cab - Air Brakes
How do you perform a spring brake test?
After the low pressure warning test…
Continue to pump the brakes
The spring brakes will pop out approximately at 40PSl. The Trailer Valve (RED) first, followed by the Tractor Valve (YELLOW) or both at the same time. NEVER the Tractor Valve (YELLOW) first.
In Cab - Air Brakes
How do you perform a air gauge test?
After the spring brake test…
Put truck in neutral & start engine
With engine at operating rpms (1200-1500), the pressure should build from 85 to 100 PSI within 45 seconds
Continue to build air pressure
The Governor will cut in at 100 PSI and 120 to 140 PSI.
In Cab - Air Brakes
What must you do before you perform the parking brake test?
Tell examiner you’re getting out to remove the wheel chock
Ensure the wheels are straight
In Cab - Air Brakes
How do you perform the parking brake test?
To test tractor brakes…
Trailer valve (RED) realease and tractor valve (Yellow) engagel
Put truck in gear
Give a couple of gentle tugs
To test trailer brakes…
Trailer Valve (Red) released
Tractor valve (YELLOW) engaged
Give a couple of gentle tugs
In Cab - Air Brakes
How do you perform a service brake test?
Place truck in low gear Release both brakes Keep wheels straight Pull ahead approximately at < 5 MPH Apply the service brakes Check to see if there is any pulling to either side & that it stops when brake is applied
