- 1 psi in 2 minutes
- 4 psi in 1 minute
- 2 psi in 1 minute
- 3 psi in 1 minute
From The CDL Manual
Test air leakage rate:
With a fully-charged air system (typically 125 psi), turn off the engine, release the service brake, and time the air pressure drop. The loss rate should be less than 2 psi in 1 minute for single vehicles and less than 3 psi in 1 minute for combination vehicles. Then apply 90 psi or more with the brake pedal. After the initial pressure drop, if the air pressure falls more than 3 psi in 1 minute for single vehicles and more than 4 psi for combination vehicles, the air loss rate is too much. Check for air leaks, and repair before driving the vehicle. Otherwise, you could lose your brakes while driving.
- 1 psi in 2 minutes
- 2 psi in 1 minute
- 4 psi in 1 minute
- 3 psi in 1 minute
From The CDL Manual
Test air leakage rate:
With a fully-charged air system (typically 125 psi), turn off the engine, release the service brake, and time the air pressure drop. The loss rate should be less than 2 psi in 1 minute for single vehicles and less than 3 psi in 1 minute for combination vehicles. Then apply 90 psi or more with the brake pedal. After the initial pressure drop, if the air pressure falls more than 3 psi in 1 minute for single vehicles and more than 4 psi for combination vehicles, the air loss rate is too much. Check for air leaks, and repair before driving the vehicle. Otherwise, you could lose your brakes while driving.
- 100 psi
- 40 psi
- 120 psi
- 125 psi
From The CDL Manual
Check air compressor governor cut-in and cut-out pressures:
Pumping by the air compressor should start at about 100 psi and stop at about 125 psi. (Check manufacturer’s specifications.)
- 100 psi
- 85 psi
- 40 psi
- 125 psi
From The CDL Manual
Check air compressor governor cut-in and cut-out pressures:
Pumping by the air compressor should start at about 100 psi and stop at about 125 psi. (Check manufacturer’s specifications.)
- Cut-in
- Cut-out
- Cut-off
- Pump-out
From The CDL Manual
Check air compressor governor cut-in and cut-out pressures:
Pumping by the air compressor should start at about 100 psi and stop at about 125 psi. (Check manufacturer’s specifications.) Run the engine at a fast idle. The air governor should cut out the air compressor at about the manufacturer’s specified pressure. The air pressure shown 67 by your gauge(s) will stop rising. With the engine idling, step on and off the brake to reduce the air tank pressure. The compressor should cut in at about the manufacturer’s specified cut-in pressure.
The pressure should begin to rise. If the air governor does not work as described above, it may need to be repaired. A governor that does not work right may not keep enough air pressure for safe driving.
- Pull against it in low gear and high RPM's
- Have another truck push from behind
- Gently pull against it in a low gear
- Gently pull against it in a high gear
From The CDL Manual
Test parking brake:
Stop the vehicle, put the parking brake on, and gently pull against it in a low gear to test that the parking brake will hold.
- Slowly forward, at about 5mph
- In reverse very quickly
- Forward at 30 mph
- Slowly backwards, then quickly forwards
From The CDL Manual
Test service brakes:
Wait for normal air pressure, release the parking brake, move the vehicle forward slowly (about 5 mph) and apply the brakes firmly using the brake pedal. Note any vehicle “pulling” to one side, unusual feel or delayed stopping action.
- Should pull to the right a bit
- Should shake a little when you apply the brakes
- Should be brought to a smooth, safe stop
- Should be brought to an abrupt stop
From The CDL Manual
Normal Stops —
To apply the air brakes during normal stops, push the brake pedal down. Control the pressure so the vehicle comes to a smooth, safe stop. If you have a manual transmission, do not push the clutch in until the engine RPM is down close to idle. When stopped, select a starting gear.
- Make very small steering wheel movements
- Apply the brakes as hard as you can without locking the wheels
- Release and reapply the brakes if the wheels lock or if large steering adjustments need to be made
- All of these things are part of controlled braking
From The CDL Manual
Controlled braking:
With this method, you apply the brakes as hard as you can without locking the wheels. Keep steering wheel movements very small while doing this. If you need to make larger steering adjustments or if the wheels lock, release the brakes. Reapply the brakes as soon as you can.
- When traveling downhill
- In a panic situation
- On snow and ice
- On vehicles without anti-lock systems
From The CDL Manual
Stab braking:
Use only on vehicles without anti-lock systems.
- Apply the brake all the way.
- Release the brakes when the wheels lock up.
- As soon as the wheels start rolling, put on the brakes fully again. (It can take up to 1 second for the wheels to start rolling after you release the brakes. If you reapply the brakes before the wheels start rolling, the vehicle will not straighten out.)