Air Brakes Trivia Quiz

Most people know about hydraulic brakes on light trucks and passenger cars, but what about the air brakes on heavy trucks and some busses? How much do you know?

A multiple-choice quiz by DelGriffith. Estimated time: 5 mins.

Author
DelGriffith

Time
5 mins

Type
Multiple Choice

Quiz #
148,165

Updated
Dec 03 21

# Qns
15

Difficulty
Tough

Avg Score
8 / 15

Plays
1158

Last 3 plays: Guest 72 (14/15), Guest 24 (12/15), Guest 70 (6/15).

This quiz has 2 formats: you can play it as a or as shown below.
Scroll down to the bottom for the answer key.

1. What is used to generate the air used to operate an air brake system? Hint

Under-hood compressor

Pre-compressed cylindered air

External compressor

Recumbent air pressure

NEXT>

2. What pressure range do most air brake systems operate at? Hint

105-125 PSI

50-90 PSI

90-100 PSI

180-200 PSI

NEXT>

3. At what level should the low-pressure warning device engage? Hint

50 PSI

60 PSI

10 PSI

30 PSI

NEXT>

4. How much push rod travel should be present in a hand-pull test for the brakes to be effective? Hint

1/4 inch

3/4 inch

1/2 inch

1 inch

NEXT>

5. What term is given to the emergency application of the "spring" or parking brakes? Hint

Travelling

Exploding

Dynamiting

Engaging

NEXT>

6. If you were towing a trailer equipped with air brakes, and your service line were to rupture, what would happen? Hint

Your trailer brakes would make an emergency application

Nothing, unless you made a service brake application

Your tractor would lose all air pressure from the reservoirs

Your brakes would become ineffective

NEXT>

7. If you were pulling a trailer, and the supply line were to rupture, what would happen? Hint

Nothing

Tractor spring brakes would make an emergency application

Tractor would lose all air pressure from the secondary reservoir

Spring brakes would make an emergency application

NEXT>

8. Automatic slack adjusters must be adjusted every day.

True

False

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9. What keeps a ready supply of air at bay near the back service brakes, so as to apply the brakes faster, and reduce brake lag? Hint

Relay valve

Automatic slack adjuster

Rear reservoir

Supply valve

NEXT>

10. Should the trailer hand valve be used to park the vehicle?

Yes

NEXT>

11. In a dual circuit air brake system, what will happen if the primary reservoir loses its air supply? Hint

The vehicle will not have any braking power

The tractor protection valve will not allow the reservoir to lose any pressure

The tractor brakes will dynamite

The vehicle will still have braking power

NEXT>

12. What prevents air from flowing from the reservoir back into the compressor? Hint

Two way check valve

Relay emergency valve

Tractor protection valve

One way check valve

NEXT>

13. What is meant by the term "compounding"? Hint

Having the tractor and trailer spring brakes engaged at the same time

Having more than one reservoir

Making a service brake application with the spring brakes engaged

Applying the service brakes and using the hand valve at the same time

NEXT>

14. In a type 30 brake chamber, how much force is exerted on the push rod if a 40 PSI brake application is made? Hint

70 PSI

1200 PSI

400 PSI

There is no such thing as a type 30 brake chamber

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15. What does the compressor do when the air system reaches operating pressure? Hint

Temporarily stops running

Goes into an unloaded stage

It has an internal cooling system

Nothing. The compressor is supposed to run hot

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Quiz Answer Key and Fun Facts

1. What is used to generate the air used to operate an air brake system?

Answer: Under-hood compressor

An under-hood compressor is used to generate the compressed air that is needed to operate an air brake system.

2. What pressure range do most air brake systems operate at?

Answer: 105-125 PSI

Although some systems operate at 85-105 PSI, the most common range is 105-125 PSI?

3. At what level should the low-pressure warning device engage?

Answer: 60 PSI

The low pressure warning device, usually consisted of a drop-down indicator, red light, buzzer, or any combination of the three, should engage at 60 PSI. If it doesn't, have your sensors checked.

4. How much push rod travel should be present in a hand-pull test for the brakes to be effective?

Answer: 1/2 inch

Using the hand pull method, there should be approximately 1/2 inch of push rod travel for effective braking, and cool running temperature.

5. What term is given to the emergency application of the "spring" or parking brakes?

Answer: Dynamiting

The spring brakes should make an emergency application when the main reservoir pressure drops to 45-20 PSI.

6. If you were towing a trailer equipped with air brakes, and your service line were to rupture, what would happen?

Answer: Nothing, unless you made a service brake application

Nothing would happen, unless you made a service brake application, which would cause air to exhaust from the reservoirs, but the tractor protection valve would stop total loss, leaving the tractor with effective braking power.

7. If you were pulling a trailer, and the supply line were to rupture, what would happen?

Answer: Spring brakes would make an emergency application

If the supply line were to rupture, the spring brakes would lose their retention charge, and make an emergency application, locking the trailer tires. The tractor protection valve would protect the tractor from total air pressure loss.

8. Automatic slack adjusters must be adjusted every day.

Answer: False

Automatic slack adjusters must be checked every day to ensure they are maintaing correct adjustment, but not necessarily adjusted every day.

9. What keeps a ready supply of air at bay near the back service brakes, so as to apply the brakes faster, and reduce brake lag?

Answer: Relay valve

A relay valve holds an air charge at bay near the rear brakes, tractor or trailer, so the the brakes can be applied faster.

10. Should the trailer hand valve be used to park the vehicle?

Answer: No

A trailer hand valve is used to independently control the trailer brakes, but should never be used to park the vehicle, as hand valves are spring loaded, and will not remain in the apply position.

11. In a dual circuit air brake system, what will happen if the primary reservoir loses its air supply?

Answer: The vehicle will still have braking power

In a dual circuit system, one reservoir controls the rear brakes, and another controls the front brakes. If one reservoir were to lose its charge, the vehicle would still have braking power, just not as much.

12. What prevents air from flowing from the reservoir back into the compressor?

Answer: One way check valve

A one way check valve prevents air from returning to the compressor from the reservoirs. This valve is usually spring loaded.

13. What is meant by the term "compounding"?

Answer: Making a service brake application with the spring brakes engaged

Compounding the brakes is making a service brake application with the spring brakes still engaged. This puts high amounts of stress on the slack adjusters and diaphragms, and can cause premature wearing of components.

14. In a type 30 brake chamber, how much force is exerted on the push rod if a 40 PSI brake application is made?

Answer: 1200 PSI

The area of the brake chamber (type 30 = 30 square inches) is multiplied by the amount of application pressure being delivered, so in this case, the amount of pressure on the push rod is 1200 PSI.

15. What does the compressor do when the air system reaches operating pressure?

Answer: Goes into an unloaded stage

The governor puts the compressor into an unloading stage when the reservoirs reach maximum operating pressure, approximately 125 PSI. When the pressure falls to about 20 PSI below the maximum operating pressure, the compressor re-engages.

Source: Author DelGriffith

This quiz was reviewed by FunTrivia editor thejazzkickazz before going online.
Any errors found in FunTrivia content are routinely corrected through our feedback system.

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