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CDL > AIR BRAKES > Flashcards

AIR BRAKES Flashcards

1
Q

During normal driving, spring brakes are usually held back by:

A

Air Pressure

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2
Q

The brake pedal in an air brake system:

A

controls the air pressure applied to put on the brakes

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3
Q

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

All air braked equipped vehicles must have what?

A

a supply pressure gage

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5
Q

If your truck or bus has a 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

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

A

s-cam drum brake

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7
Q

Parking or emergency brakes of trucks and buses can be legally held on by what?

A

spring pressure

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8
Q

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

A

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

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9
Q

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 tank and cause brakes to fail

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10
Q

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

A

stop and park safely ASAP

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11
Q

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

60 psi

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12
Q

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

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

A

level ground, chock the wheels, and release the parking brakes

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14
Q

If your vehicle has an alcohol evaporator, every day during cold weather you should:

A

check and fill the alcohol level

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15
Q

For air brake systems in good condition, the air compressor should start pumping at what psi?

A

100 psi

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16
Q

A straight truck or bus system should not leak at a rate of more than _ psi per minute with the ENGINE OFF and the BRAKES RELEASED?

A

2 psi

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17
Q

A slack adjustor probably needs adjustment if it moves more that _ when you pull on it.

A

1 inch

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18
Q

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

A

35 MPH

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19
Q

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

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

A

more than 300 feet

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21
Q

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

The braking power of the spring brakes

A

depends on the service brakes being in adjustments

23
Q

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

The proper method of braking when going downhill is to reduce your speed by _ MPH below your safe speed before releasing brakes

A

5 MPH

25
Q

Which of the following about ABS is true?

A

ABS changes the way you brake in an emergency

26
Q

If your ABS is not working, you should

A

drive normally, but get the system serviced soon

27
Q

The stop light switch

A

turns on the brake lights to warn others behind you

28
Q

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

A

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

29
Q

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

A

never

30
Q

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

A

before driving

31
Q

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

A

150 PSI

32
Q

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

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

In air braked vehicles, the parking brake should be used

A

anytime the vehicle is parked

35
Q

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

A

when the brakes are very hot

36
Q

Emergency controlled braking is when you

A

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

37
Q

The application pressure gauge shows you how much pressure

A

you’re applying to the brakes

38
Q

The supply pressure gauge shows how much pressure

A

is in the air tanks

39
Q

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

A

at the end of each day of driving

40
Q

The spring brakes on trucks will bring it to a stop automatically when air pressure falls to what range

A

20-45 psi

41
Q

The air compressor should stop pumping at what psi?

A

125 psi

42
Q

Modern air brakes combine 3 different systems. The service, parking, and _
brakes.

A

emergency

43
Q

The s-cam

A

forces the brake shoes to the drums

44
Q

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

Excessive use of the service brakes results in overheating, which can lead to

A

expansion of the brake drum

46
Q

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

A

45 seconds

47
Q

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

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

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

A

brake leg

50
Q

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

A

brakes to fade/fail

51
Q

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

A

YELLOW

52
Q

The modulating control valve allow you to operate the

A

spring brakes

53
Q

Cracks in the drum can not be longer than _ the width of the friction area

A

1/2 inch

54
Q

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

A

32 ft

CDL (3 decks)

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