Quote 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.
What is the maximum leakage rate for a combination vehicle?
When performing a static leakage test on a double combination vehicle with air brakes, the leakage rate should be no more than 3 psi in one minute. If the air leaks from the air brake system at a quicker rate, the vehicle should not be driven because something likely needs to be repaired.
What is maximum leakage rate?
6. What are the maximum leakage rates? Less than four psi in one minute for single vehicles and less than eight psi in one minute for combination vehicles. Less than two psi in one minute for single vehicles and less than three psi in one minute for combination vehicles.
What is the maximum leakage rate for a single vehicle with air brakes?
A single vehicle with air brakes should have a leakage rate no higher than 3 psi in a minute during an applied leakage test.
What is the maximum operating air pressure?
Actual cut-out pressure must never be higher than 1000 kPa (145 psi ). Actual cut-in pressure must never be less than 552 kPa (80 psi ). The air brake system is defective when cut-out pressure is above 1000 kPa (145 psi ) or cut-in pressure is below 552 kPa (80 psi ).
When the spring brakes are on you should never?
Never apply the brake pedal if your spring breaks are activated. Brakes can be damaged if they are subject to both springs and air pressure.
What is the proper way to test the air leakage rate?
Test air leakage rate:
With a fully-charged air system (typically 125 psi), turn off the engine, release the parking 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.
What is the maximum leakage rate for a triple combination vehicle?
A triple combination should have a leakage rate no higher than 6 psi in a minute during an applied leakage test.
What is stab braking?
Stab braking:
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.
Why must air tanks be drained?
Compressed air usually has some water and some compressor oil in it, which is bad for the air brake system. For example, the water can freeze in cold weather and cause brake failure. The water and oil tend to collect in the bottom of the air tank. … You must drain the tanks yourself at the end of each day of driving.
How often should you drain air tanks?
If using air tanks with manually operated drains, how often should you drain the tanks? To prevent the build up of oil and water in a vehicle’s air tanks, manually operated air tank drains should be used at the end of each day of driving.
What is the proper braking technique?
Once the vehicle is in the proper low gear, the following is the proper braking technique: Apply the brakes just hard enough to feel a definite slowdown. When your speed has been reduced to approximately 5 mph below your “safe” speed, release the brakes. (This brake application should last about 3 seconds.)
How should you check if your service brakes are working properly?
How should you check that your service brakes are working properly? Wait for normal air pressure, release the parking brake, move the truck forward slowly, and apply the brake pedal firmly. You just studied 70 terms!
What does Fmvss 121 mean?
It establishes performance and equipment requirements for braking systems on vehicles equipped with air brake systems, including separately controlled parking brakes of prescribed holding capability, automatic brake adjusters and adjustment indicators, and emergency brakes which activate automatically in the event of …
How fast should a truck build air pressure?
Air pressure build-up from 85 psi to 100 psi should take 45 seconds or less. While driving, observe the air pressure gauge during build-up to ensure proper air system operation. braking, pull over at a safe place and perform the 2 minute / 5 psi leakage test.
At what PSI do air brakes lock up?
If the pressure in the air system pulls below 60 psi, the parking brake knob will pop out and set the parking brakes. This is a safety feature so the truck will stop, because if the pressure falls too low, the service brakes will not work. The other system component stops the vehicle when you push on the brake pedal.