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CDL Answers > Air Brakes > Flashcards

Air Brakes Flashcards

1
Q

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

A

air pressure

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2
Q

2) The brake pedal in an air brake system:

A

controls the air pressure

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3
Q

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

A

Service system

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4
Q

4) All air brake equipped vehicles must have what?

A

a supply pressure gauge

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5
Q

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

A

release the spring brakes to move the vehicle in an emergency

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6
Q

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

A

s-cam drum brake

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7
Q

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

A

spring pressure

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8
Q

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

A

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

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9
Q

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

A

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

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10
Q

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

A

stop and park safely as soon as possible

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11
Q

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?

A

60psi

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12
Q

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

A

let the air out of the system

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13
Q

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

A

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

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14
Q

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

A

check and fill the alcohol level

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15
Q

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

A

100

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16
Q

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.

A

2

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17
Q

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

A

1

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18
Q

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?

A

35

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19
Q

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

A

The braking effect of the engine

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20
Q

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

A

more than 300 feet

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21
Q

21) Emergency stab braking is when you:

A

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

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22
Q

22) The braking power of the spring brakes:

A

depends on the brakes being in adjustment

23
Q

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

A

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

24
Q

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?

A

5

25
Q

25) Which of the following about ABS is true?

A

ABS changes the way you brake in an emergency

26
Q

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

A

Drive normally, but get the system serviced soon

27
Q

27) The stop light switch:

A

turns on the brake lights to warn others behind you

28
Q

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

A
  • your air pressure may drop to low while driving, requiring an emergency stop
29
Q

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

A

never

30
Q

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

A

before driving

31
Q

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

A

150

32
Q

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?

A

3 psi in 1 minute

33
Q

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

A

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

34
Q

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

A

any time the vehicle is parked

35
Q

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

A

if the brakes are very hot

36
Q

36) Emergency controlled braking is when you:

A

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

37
Q

37) The application pressure gauge shows how much pressure:

A

you are applying to the brakes

38
Q

38) The supply pressure gauge shows how much pressure:

A

is in the air tanks

39
Q

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

A

At the end of each day of driving

40
Q

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

A

20-45psi

41
Q

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

A

125

42
Q

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

A

emergency

43
Q

43) The s-cam:

A

forces the brake shoes to the drums

44
Q

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

A

either the front or rear brakes will not be operating fully

45
Q

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

A

expansion of the brake drum

46
Q

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

A

45 seconds

47
Q

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

A

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

48
Q

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

A

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

49
Q

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

A

Brake lag

50
Q

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

A

brakes to fade or fail

51
Q

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

A

yellow

52
Q

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

A

spring brakes

53
Q

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

A

1/2 (half)

54
Q

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

A

32 feet

CDL Answers (3 decks)

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