Air Brakes

Question 1

1) Durning normal driving, spring brakes are normally held back by:

Answer 1

air pressure

Question 2

2) The brake pedal in an air brake system:

Answer 2

controls the air pressure

Question 3

3) The brake system that applies and releases the brakes when the driver uses the brake pedal is what system?

Answer 3

Service system

Question 4

4) All air brake equipped vehicles must have what?

Answer 4

a supply pressure gauge

Question 5

5) If your truck or bus has dual parking control valve, you can use pressure from another tank to:

Answer 5

release the spring brakes to move the vehicle in an emergency

Question 6

6) The most common type of foundation brake found on heavy vehicles is the:

Answer 6

s-cam drum brake

Question 7

7) Parking or emergency brakes of trucks and busses can be legally held on by what?

Answer 7

spring pressure

Question 8

8) If your vehicle has an alcohol evaporator, it is there to:

Answer 8

reduce the risk of ice valves and other parts in cold weather

Question 9

9) Some air brake systems have an alcohol evaporator. What might happen if you don’t keep the unit filled with alcohol?

Answer 9

Ice may form in the tanks and cause the brakes to fail.

Question 10

10) The most important thing to do when the low air pressure warning comes on is:

Answer 10

stop and park safely as soon as possible

Question 11

11) The driver must be able to see a low air pressure warning that must come on before pressure in the tanks fall below what?

Answer 11

60psi

Question 12

12) Under normal conditions, in order to engage the parking brake the driver must first:

Answer 12

let the air out of the system

Question 13

13) To check the free play of manual slack adjustors on s-cam brakes, you should park on:

Answer 13

level ground, choke the wheels, and release the parking brake

Question 14

14) If your vehicle has an alcohol evaporator, every day durning cold weather you should:

Answer 14

check and fill the alcohol level

Question 15

15) For air brakes systems in good conditions, the air compressor should start pumping at what psi?

Answer 15

100

Question 16

16) A straight truck or bus system should not leak at a rate more than _ psi per minute with the engine off and the brakes released.

Answer 16

2

Question 17

17) A slack adjustor probably needs adjustment if it moves more than _ inch when you pull on it.

Answer 17

1

Question 18

18) If you are driving down a steep downgrade and you have reached your safe speed of 40mph, you should apply the service brakes until your speed reaches what?

Answer 18

35

Question 19

19) The use of brakes on a long and/or steep downgrade is only a supplement to:

Answer 19

The braking effect of the engine

Question 20

20) Under ideal conditions, a truck with air brakes going 55mph would require a stopping distance of what?

Answer 20

more than 300 feet

Question 21

21) Emergency stab braking is when you:

Answer 21

brake as hard as you can, release the brakes when the wheels lock, and apply the brakes again when the wheels roll.

Question 22

22) The braking power of the spring brakes:

Answer 22

depends on the brakes being in adjustment

Question 23

23) If you must make an emergency stop, you should brake so you:

Answer 23

can keep your vehicle in a straight line and turn if it becomes necessary

Question 24

24) The proper method of braking when going down hills is: to reduce your speed by _mph below your safe speed before releasing the brakes?

Answer 24

5

Question 25

25) Which of the following about ABS is true?

Answer 25

ABS changes the way you brake in an emergency

Question 26

26) If your ABS is not working, you should:

Answer 26

Drive normally, but get the system serviced soon

Question 27

27) The stop light switch:

Answer 27

turns on the brake lights to warn others behind you

Question 28

28) If air pressure does not build up to normal within the correct amount of time:

Answer 28

- your air pressure may drop to low while driving, requiring an emergency stop

Question 29

29) If the spring brakes are on, when should you push the brake pedal?

Answer 29

never

Question 30

30) If your truck’s compressor has its own supply, when should you first check the oil level?

Answer 30

before driving

Question 31

31) The safety valve is set automatically to reduce pressure in the tanks at what psi?

Answer 31

150

Question 32

32) The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than what?

Answer 32

3 psi in 1 minute

Question 33

33) Air brakes take more time to stop than hydraulic brakes because:

Answer 33

air takes more time to flow through the lines than hydraulic fluid

Question 34

34) In air brake vehicles, the parking brake should be used:

Answer 34

any time the vehicle is parked

Question 35

35) Which of these is not the proper time to apply the parking brakes?

Answer 35

if the brakes are very hot

Question 36

36) Emergency controlled braking is when you:

Answer 36

apply the brakes as hard as you can without locking the wheels

Question 37

37) The application pressure gauge shows how much pressure:

Answer 37

you are applying to the brakes

Question 38

38) The supply pressure gauge shows how much pressure:

Answer 38

is in the air tanks

Question 39

39) How often should you drain the water and oil from your air tanks?

Answer 39

At the end of each day of driving

Question 40

40) The spring brakes on trucks will bring it to a stop automatically when air pressure fails to what range?

Answer 40

20-45psi

Question 41

41) The air compressor should stop pumping at what psi?

Answer 41

125

Question 42

42) Modern air brakes combine 3 different systems. The service, parking and ________ brakes.

Answer 42

emergency

Question 43

43) The s-cam:

Answer 43

forces the brake shoes to the drums

Question 44

44) If your truck has a dual air system, and 1 system is low on air pressure:

Answer 44

either the front or rear brakes will not be operating fully

Question 45

45) Excessive use of the service brakes result in overheating, which can lead to:

Answer 45

expansion of the brake drum

Question 46

46) If your truck has properly functioning dual air systems, the pressure should build from 85 psi to 100 psi in how long?

Answer 46

45 seconds

Question 47

47) You should know that your brakes are fading when:

Answer 47

you have to push harder and harder on the brake pedal to control your speed

Question 48

48) How should you check that your service brakes are working properly?

Answer 48

Park on level ground, release the parking brakes, roll forward slowly and apply the brakes using the pedal.

Question 49

49) Total stopping distance for air brakes is longer than hydraulics because of what?

Answer 49

Brake lag

Question 50

50) Excessive heat caused by using your brakes too often can cause the:

Answer 50

brakes to fade or fail

Question 51

51) If a truck or bus has ABS, it will have a ______ malfunction lamp on the instrument panel.

Answer 51

yellow

Question 52

52) The modulating control valve allow you to operate the:

Answer 52

spring brakes

Question 53

53) Cracks in the drum can be no longer than _ the the width of the friction area.

Answer 53

1/2 (half)

Question 54

54) The air brake lag at 55mph adds how many feet of stopping distance?

Answer 54

32 feet