Air Brakea

Question 1

When a vehicle stops,there is friction between the brake lining and drum, or the brake pad and rotor. What does this friction create?

Answer 1

Heat

Question 2

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)?

Answer 2

1.5 seconds

Question 3

Why does it take longer for a heavy vehicle to stop then a passenger vehicle?

Answer 3

Vehicle weight

Question 4

What impact does vehicle speed have on a vehicles stopping capability?

Answer 4

The faster vehicle is traveling, the more power it needs to stop.

Question 5

What can happen in situations of excessive hard braking?

Answer 5

Heat build up can result in brake fade, brake damage or brake failure.

Question 6

What does the term perception time mean?

Answer 6

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.

Question 7

Vehicles stopping time consists of 4 different times including:

Answer 7

1.perception time
2.reaction time
3.brake lag time
4.braking time

Question 8

Brake lag time of approximately—– of a second from when the brake is applied to when the brakes begin to function.

Answer 8

4/10 of a second

Question 9

What is the term called for the actual time that the vehicle takes to stop once the brakes are applied?

Answer 9

Braking time

Question 10

—— is the sum of the perception time, reaction time, brake lag time and braking time

Answer 10

Total stopping time

Question 11

2 times vehicle weight requires ‐———- the stopping power

Answer 11

2 times

Question 12

2 times vehicle speed requires——— times the stopping power

Answer 12

4 times

Question 13

2 times vehicle speed and 2 times vehicle weight requires ———— times the stopping power

Answer 13

8 times

Question 14

Heavy trucks should allow how many seconds between them and the car in front of them?

Answer 14

4 seconds

Question 15

If there are 16 brakes how much braking power should each brake give?

Answer 15

1/16th of the braking force for each brake.

Question 16

What is the maximum heat brake components should give off for optimal performance.?

Answer 16

250 degree maximum

Question 17

Why do heavy vehicles use air brakes instead of hydraulic brakes?

Answer 17

More braking power and increases safety

Question 18

Identify one advantage and one disadvantage of compressed air?

Answer 18

Adavntage: generates more braking force.
Disadvantage: can be dangerous

Question 19

What are compressed air dangers and how do u protect yourself?

Answer 19

Compressed air directed at body can cause injury. Use caution when draining air tanks. Make sure air is drained before repair.

Question 20

Why is it important to learn about air brakes?

Answer 20

For the safety of the driver and other drivers on the road.

Question 21

Who is responsible for ensuring that the air brakes have been correctly adjusted?

Answer 21

The driver

Question 22

What is the common standard for measuring air pressure?

Answer 22

Pounds per square inch

Question 23

How is a compressors performance measured.?

Answer 23

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.

Question 24

Describe the difference between cut-out and cut in pressure.

Answer 24

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.

Question 25

What is the purpose of the safety valve?

Answer 25

Protects the tank from excessive air pressure, which leads to system failures if the governor fails to cut out the compressor.

Question 26

Describe two common moisture and contamination control devices?

Answer 26

Air dryer: removes moisture and contamination from air and expels it into the atmosphere.
Inclined alcohol injector: adds a small amount of alcohol vapor into system to prevent freezing.

Question 27

How often should air tanks be drained?

Answer 27

Should be drained at end of each work shift.