Air Brakea Flashcards
(27 cards)
When a vehicle stops,there is friction between the brake lining and drum, or the brake pad and rotor. What does this friction create?
Heat
How long does it take for a driver to see a hazard, think about stopping, and place his/her foot on the brake(I.e perception time plus reaction time)?
1.5 seconds
Why does it take longer for a heavy vehicle to stop then a passenger vehicle?
Vehicle weight
What impact does vehicle speed have on a vehicles stopping capability?
The faster vehicle is traveling, the more power it needs to stop.
What can happen in situations of excessive hard braking?
Heat build up can result in brake fade, brake damage or brake failure.
What does the term perception time mean?
It is the time it takes between recognizing a hazard ahead and beginning to react. An average drivers perception time is about 3/4 of a second.
Vehicles stopping time consists of 4 different times including:
1.perception time
2.reaction time
3.brake lag time
4.braking time
Brake lag time of approximately—– of a second from when the brake is applied to when the brakes begin to function.
4/10 of a second
What is the term called for the actual time that the vehicle takes to stop once the brakes are applied?
Braking time
—— is the sum of the perception time, reaction time, brake lag time and braking time
Total stopping time
2 times vehicle weight requires ‐———- the stopping power
2 times
2 times vehicle speed requires——— times the stopping power
4 times
2 times vehicle speed and 2 times vehicle weight requires ———— times the stopping power
8 times
Heavy trucks should allow how many seconds between them and the car in front of them?
4 seconds
If there are 16 brakes how much braking power should each brake give?
1/16th of the braking force for each brake.
What is the maximum heat brake components should give off for optimal performance.?
250 degree maximum
Why do heavy vehicles use air brakes instead of hydraulic brakes?
More braking power and increases safety
Identify one advantage and one disadvantage of compressed air?
Adavntage: generates more braking force.
Disadvantage: can be dangerous
What are compressed air dangers and how do u protect yourself?
Compressed air directed at body can cause injury. Use caution when draining air tanks. Make sure air is drained before repair.
Why is it important to learn about air brakes?
For the safety of the driver and other drivers on the road.
Who is responsible for ensuring that the air brakes have been correctly adjusted?
The driver
What is the common standard for measuring air pressure?
Pounds per square inch
How is a compressors performance measured.?
Build up time capacity to build air pressure from 50 psi to 90 psi in 3 minutes or less with engine running at 1200 rpm.
Describe the difference between cut-out and cut in pressure.
Cut out: when system reaches max air pressure 120-135 psi governor causes compressor to stop supplying air to tanks.
Cut in: when system airnpressure drops by approximately 20- 25 psi the governor causes compressor to start supplying air to tanks.
