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CDL > Air Brakes > Flashcards

Air Brakes Flashcards

1
Q

The application pressure gauge shows how much air pressure you:

A

Are applying to the brake

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2
Q

The spring brakes used on the chambers in a straight truck will bring you to a stop when air pressure drops below ___ psi.

A

20

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3
Q

Some air brake systems have an alcohol evaporator. What may happen if you don’t keep the proper level of an alcohol evaporator?

A

Ice may form in the storage tank and cause brake failure.

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4
Q

Your truck or bus has a dual air brake system. If a low air pressure warning comes on for only one system, what should you do?

A

Bring your vehicle to a complete stop right away and safely park. Continue only after the system is fixed.

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5
Q

Why drain water from compressed air tanks?

A

Water can freeze in cold weather and cause brake failure.

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6
Q

The safety valve is set automatically when pressure is:

A

150

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7
Q

Your truck has a dual air system and one of the systems loses its pressure. What will happen?

A

Either the front or back brake will not be fully operational.

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8
Q

Parking or emergency brakes of trucks and buses can be legally held on by _______ pressure.

A

Spring

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9
Q

If your truck or bus has dual parking control valves, you can use pressure from a seperate tank to:

A

Release the spring emergency/parking brakes to move a short distance.

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10
Q

If your truck has a properly functioning dual air brake system and minimum size air tanks, the air pressure should build up from 85 to 100 psi within how many seconds?

A

45

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11
Q

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

A

Park on level ground, wait until normal air pressure is reached, release the parking brake and move forward slowly at about 5 mph, then apply the brakes firmly.

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12
Q

A straight truck or bus air brake system should not leak at the rate of more than ___ psi per minute with the engine off and the brakes realeased.

A

2

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13
Q

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

A

Air pressure

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14
Q

The air compressor stops pumping air at what psi?

A

125

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15
Q

The driver must be able to see a low air pressure warning which comes on before pressure in the service air tanks falls below ___ psi.

A

60

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16
Q

Excessiv use of the service brakes results in the overheating which can lead to:

A

Expansion of the brake drums

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17
Q

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

A

S-cam drum

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18
Q

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

A

Can steer and so your vehicle stays in a straight line.

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19
Q

Your truck or bus has a dual air brake system. If a low pressure warning comes on for only one system, what should you do?

A

Stop right away and safely park. Continue only after the system is fixed.

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20
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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21
Q

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

A

3 psi in one minute

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22
Q

The driver ust be able to see a low pressure warning which comes on before pressure in the service air tanks falls below ___ psi.

A

60

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23
Q

The braking power of the spring brakes:

A

Depends on the service brakes being in adjustment

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24
Q

The air brake lag distance at 55 mph on dry pavement adds about ___ feet.

A

32

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25
Total stopping distance for air brakes is longer than that for hydraulic brakes due to ____ distance.
Brake lag
26
It is accepted that too much heat caused by using your brakes too often can also cause:
Brakes to fade or fail
27
Repeated partially releasing and pressing the brake pedal may result in:
A loss of air pressure
28
The brake system that applies and releases the brakes when the driver uses the brake pedal is the ____ brake system.
Service
29
A slack adjuster's free play needs to be adjusted if it is more than about ___ when you pull hard on it.
1 inch
30
An air brake system is fully charged at what psi?
125
31
The brake pedal in an air brake system:
Controls the air pressure applied to put on the brakes.
32
The S-cam:
Forces the brake shoe against the inside of the brake drums.
33
Under normal conditions, in order to engage the parking brakes, the driver should:
Let the air out of the air brake system.
34
All air brake equipped vehicles have:
A supply pressure gauge
35
With air brake vehicles, the parking brakes should be used:
Whenever you leave the vehicle unattended
36
Which of these is NOT a proper time to apply the parking brakes?
To brake vehicle very hard, in other words when coming down the steep grade.
37
With air brake vehicles, the parking brakes should be used:
Any time when vehicle is parked.
38
Why should you drain water from compressed air tanks?
Water can freeze in cold weather and cause brake failure
39
If the spring brakes are on, when should you push the brake pedal?
Never
40
To check the free play of manual slack adjusters of S-cam brakes, you should park on:
Level ground, chock the wheels, and release the parking brakes.
41
Excessive heat caused by using your brakes too often can also cause:
Brakes to fade or fail
42
The use of brakes on a long and steep downgrade under normal conditions is only a supplement to:
The braking effect of the engine.
43
The most important thing to do when a low pressure warning comes on is:
Stop and safely park as soon as possible
44
The parking or emergency brake on a heavy vehicle can only be held in position by something that cannot leak away, like:
Spring pressure
45
Air braking takes more time than hydraulic braking because:
It takes more time to flow through the lines than hydraulic fluid
46
When brakes are applied, the brake shoes will press against the:
Brake drum or disc
47
The safety valve discharges automatically at the pressure of ___ psi
150
48
Emergency stab braking is:
Press on the brake pedal as hard as you can, release the brakes when the wheels lock, and put on the brakes again when the wheels start rolling
49
If air pressure is not built up within the correct amount of time, then:
Your air pressure may drop to a low point while driving, requiring an emergency stop.
50
The safety valves reduces pressure at what PSI?
150
51
When brakes are applied, the brake shoes will align to press against the:
Brake drum or disc
52
The supply pressure gauge shows how much pressure:
Is in the air tanks
53
The braking power of spring brakes:
Depends on the service brakes being in adjustment.
54
Your brakes are fading when
You have to push harder on a brake pedal to control your speed on a downgrade
55
If your vehicle has an alcohol evaporator, it is there to:
Reduce the risk of icing in air brake valves in cold weather
56
The air compressor governor controls:
When air is pumped into the air tanks
57
Modern air brake systems combine three different systems. The are the service, the parking, and the _______ brakes.
Emergency
58
If you do not have automatic tank drains, how often should you drain the oil and water from the bottom of compressed air storage tanks?
At the end of each day of driving
59
The proper use of the brakes when going down a long steep grade after selecting a proper gear, is to brake until your speed is about ___ below the posted speed for your safety, and release your brake.
5 mph
60
In ideal conditions, a truck or bus with an air brake, going at 55 mph would require a stopping distance of how many feet?
More than 300 feet
61
When is it OK to leave your truck unattended without applying the parking brakes and chocking the wheels?
Never
62
The stop light switch
Turns on your brake lights to warn drivers behind you
63
It is not safe to drive a vehicle that has brake drums with cracks that are longer than ___ the width of the friction area
1/2
64
To test air service brakes you should:
Brake firmly while slowly moving forward
65
If you are driving down to the steep downgrade and you have reached the speed limit of 40 mph, you would apply the service brake until your speed dropped below ____ mph
35

CDL (2 decks)

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