Air Brakes Flashcards
(30 cards)
What can cause brakes to fail or fade?
Excessive use of the service brakes, not relying on engine braking enough, and brakes being out of adjustment.
Which device helps reduce the risk of ice in the air brake systems during cold weather?
Alcohol evaporator
Slack adjusters are:
Between the power screw and push rod on disc brakes, part of your air brake system used to adjust the brakes, and between the push rod and S-cam on drum brakes.
What is the correct way to slow a large vehicle down on long downgrades?
Using a low gear and driving more slowly.
What should you never do when the spring brakes are on?
Push the brake pedal down.
Pressing on the brakes as hard as you can, releasing when they lock up, then pressing the brakes fully again when the wheels are rolling is called what?
Stab braking.
If the brakes are wet, what can be done to dry them out?
Use the brakes lightly while driving in low gear.
What is a reason that air tanks must be drained?
Your brakes may fail due to the water freezing.
Where is compressed air stored?
Main reservoirs
Most heavy-duty vehicles have dual air brake systems. What is a dual air brake system?
Two separate air brake systems that use a single set of brakes controls.
In a dual air brake system, which parts of braking does each system typically operate?
One system operates the brakes on the rear axle/axles, the other operates the regular brakes on the front axle (and possibly a rear axle). Both supply air to the trailer.
Spring brakes are?
Made up of powerful springs that are held in back while you are driving by air pressure, brakes that come on automatically on a truck or tractor when the PSI drops too low, not going to have full effect until your PSI drops to a certain range, often 20 to 30 PSI.
When should you not use the parking brakes when parking?
If the brakes are very hot or very wet in freezing temperatures.
When ABS fails can you still drive your truck?
Yes, you will still have normal brake function and simply need to get the ABS repaired soon.
How do brakes work on a long, steep downgrade?
As a supplement to the braking effect of your engine.
How would you check your truck’s slack adjusters?
Use gloves and pull hard on each slack adjusters you can reach.
To test the air leakage rate, one must turn off engine(with a fully charged air system), turn the key to the on position, release the service brake, and do what?
Time the air pressure drop.
If you press and release the brake pedal rapidly, what will happen?
You can let the air out faster than the compressor can replace it.
What is a modulating control valve?
A lever used to apply the spring brakes gradually.
Chemical changes in the braking lining, which reduce friction and cause expansion on the brake drums is known as what?
Brake fade
Why is it especially important to have your brakes adjusted before going down steep grades?
Some brakes will do more work than others.
What is true about a dual air brake system?
One is called the primary system and one is called the secondary system, one system usually operates the front axle and one operates the rear axle, they use a single set of brake controls.
With air brakes, there is an added delay when stopping. What causes this?
The time required for the air to flow through the lines to the brakes.
If parking brakes are not being used when vehicle is parked, what must be done instead?
Use wheel chocks
