80 Air Brake Questions

Question 1

Oil and water usually collect in compressed air
tanks. If you d on o t have a n automatic tank drain, when should you drain the air tanks?

Answer 1

After every working day

Question 2

To check the slack adjusters on S c a m brakes, you should

Answer 2

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

Question 3

The safety valve is set to automatically reduce pressure at ___ psi

Answer 3

150

Question 4

If your truck has a properly functioning dual air brake system and minimum-size air tanks, the air pressure should build from 85 to 100 psi within __ seconds.

Answer 4

45

Question 5

During normal driving, spring brakes are usually held back by

Answer 5

Air pressure

Question 6

The driver must be able to see a warning before the pressure in the service air tanks falls below __ psi.

Answer 6

60

Question 7

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

Answer 7

Expansion of the brake drums

Question 8

When you are going down a long or steep grade after selecting the proper gear, the proper method of braking is to brake until your speed is about ___ miles
per hour below your «safe» speed and then release your brakes.

Answer 8

5

Question 9

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

Answer 9

32

Question 10

How can you check the slack adjusters?

Answer 10

Park on level ground, turn off the parking brakes, and pull had on each slack adjuster. It shouldn’t move more than one inch

Question 11

The total stopping distance for air brakes is longer than that for hydraulic brakes because of

Answer 11

Brake lag

Question 12

Repeatedly pressing and releasing (fanning) the brake pedal m a y result in

Answer 12

A loss of brake air pressure

Question 13

The parking or emergency brake on a heavy vehicle can only be held in position by something that cannot leak away, like

Answer 13

Spring pressure

Question 14

Air braking takes more time than hydraulic braking because air

Answer 14

Takes more time to flow through the lines than hydraulic fluid

Question 15

When you apply the brakes, the brake shoes/linings are pressed against the

Answer 15

Brake drum

Question 16

It is not safe to drive a vehicle that has brake drums with cracks that are longer than __ of the width of the friction area.

Answer 16

1/2

Question 17

The emergency brake system

Answer 17

Uses parts of the service brake and parking brake systems to stop the vehicle in the event of a brake system failure.

Question 18

What is a dual air brake system?

Answer 18

A two-brake system; one brake operates the front brakes and one operates the back brakes

Question 19

Before starting down a hill, you should be in the proper gear

Answer 19

So you only have to apply the brake just hard enough to feel a definite slowdown

Question 20

The driver must be able to see a low pressure
warning, which comes on before pressure in the service air tank falls below___ psi.

Answer 20

60

Question 21

Modern air brake systems are three different systems combined: the service brakes, parking brakes, and ___ brakes

Answer 21

Emergency

Question 22

The air supply pressure gauge shows how much pressure

Answer 22

Is in the air tanks

Question 23

The parking or emergency brakes of trucks or buses can legally be held by __ pressure.

Answer 23

Spring

Question 24

The stop light switch

Answer 24

Turns on the brake lights to warn drivers behind you.

Question 25

With air brake-equipped vehicles, the parking brakes should be used

Answer 25

Whenever you leave the unattended

Question 26

For air brake systems in good condition, the air compressor should start pumping at about __ psi.

Answer 26

100

Question 27

An air brake system is fully charged at __ psi.

Answer 27

125

Question 28

The air compressor governor controls

Answer 28

When air is pumped into the air storage tanks

Question 29

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

Answer 29

Check and fill the alcohol level

Question 30

Emergency controlled braking is when you

Answer 30

Apply the brakes as had as you can without locking the wheels

Question 31

Water should be drained from the compressed air tanks

Answer 31

Because water can freeze in cold weather and cause brake failure

Question 32

What is the danger of non-functioning low pressure warning signal?

Answer 32

This could cause sudden emergency braking in a single-circuit air system

Question 33

You know that your brakes are fading when

Answer 33

You have to press the brake pedal harder to control speed on a downgrade

Question 34

Tractor and straight truck spring brakes will come fully on when the air pressure drops to a range of __ psi.

Answer 34

20 to 45

Question 35

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

Answer 35

Either the front or rear brake will not be fully operational

Question 36

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

Answer 36

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

Question 37

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

Answer 37

S-cam drum

Question 38

If you must make an emergency stop, brake so that you

Answer 38

Can steer and you vehicle will stay in a straight line

Question 39

The brake system that applies and releases the brakes when the driver presses the brake pedal is the __ brake system.

Answer 39

Service

Question 40

The brake pedal in an air brake system

Answer 40

Controls the air pressure applied to the brakes

Question 41

To engage the parking brakes under normal conditions, the driver must first

Answer 41

Let the air out of the spring brakes

Question 42

Air tanks must be drained

Answer 42

To drain moisture and oil out of the tanks

Question 43

What are spring brakes?

Answer 43

If the air brakes leak down, springs apply the brakes to stop the vehicle

Question 44

The use of air brakes on a downgrade is only a supplement to the

Answer 44

Braking effect of the engine

Question 45

When you apply the brakes by pushing down on the brake pedal,

Answer 45

Air pressure is applied to the brake pads

Question 46

What is a slack adjuster?

Answer 46

It is an adjusting nut on the backside of the brake drum, used for adjusting the brakes

Question 47

Air-brake equipped vehicles have

Answer 47

An air supply pressure gauge

Question 48

To test the static air leakage rate, you should

Answer 48

Turn off the engine, release all brakes, and let the system settle

Question 49

When is it OK to leave your truck unattended without applying parking brakes or chocking the wheels?

Answer 49

Never

Question 50

What factors can cause brakes to fade or fail?

Answer 50

Overheating, low air pressure, and not relying on the engine braking effect

Question 51

If oil and water collects in the air tanks, what could happen to the brakes?

Answer 51

The brakes could fail

Question 52

To correct a drive-wheel braking skid, you should

Answer 52

Stop braking, turn quickly, and counter steer

Question 53

You are on a steep downgrade and have reached your safe speed of 4 0 mph. You would apply the service brakes until your speed drops to __ mph

Answer 53

35

Question 54

Some air brake systems have an alcohol evaporator. What may happen if you don't keep the unit filled with alcohol?

Answer 54

Ice may form in the air storage tanks and cause the brakes to fail

Question 55

Before you drive a truck or bus with a dual air brake system, the pressure in each air brake system should be at least __ psi.

Answer 55

100

Question 56

If pressure is not built up fast enough,

Answer 56

The air pressure may drop too low during driving

Question 57

When you pull hard on a slack adjuster, if its free play is more than __, the slack adjuster will need to be adjusted.

Answer 57

1 inch

Question 58

How should you check that the spring brakes come on when the air pressure in the system drops below a certain level?

Answer 58

Park on level ground, chock the wheels, release the parking brake when you have enough air pressure, shut the engine off, and repeatedly press and release the brake pedal

Question 59

In air brake vehicles, the parking brakes should be used

Answer 59

Anytime the vehicle is parked

Question 60

To make an emergency stop with air brakes, using the stab braking method, you should

Answer 60

Press on the brake pedal as hard as you can, release the brakes when the wheels lock, and apply the brakes again when the wheels start to roll

Question 61

If the air compressor should develop a leak, what keeps the air in the tanks?

Answer 61

The one-way check valve

Question 62

The application pressure gauge shows how much pressure you have

Answer 62

When you are applying the brakes

Question 63

The braking power of the spring brakes

Answer 63

Depends on the service brakes being in adjustment

Question 64

It is accepted that too much heat caused by using your brakes too often can also cause

Answer 64

Brake fade or failure

Question 65

The S-cam

Answer 65

Forces the brake shoes against the inside of the brake drum

Question 66

Converter dollies built on or after March 1, 1998 are required to have anti-lock brakes. These dollies will have

Answer 66

A yellow malfunction lamp on the left side of the dolly

Question 67

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

Answer 67

Never

Question 68

What is the first thing you should do when a low air pressure warning comes on?

Answer 68

Stop and safely park as soon as possible

Question 69

In ideal conditions, a truck or bus equipped with an air brake and traveling at 55 mph would require what stopping distance?

Answer 69

More than 450 feet

Question 70

What do air brakes use to make the brakes work?

Answer 70

Compressed air

Question 71

The parking brake applies and releases

Answer 71

The parking brakes when you use the parking brake control

Question 72

The S-cam forces the brake shoes away from one another and presses them against the inside of the brake drum. It is called the S-cam because

Answer 72

It is shaped liked the letter <>

Question 73

How can you test the low pressure warning signal?

Answer 73

Shut off the engine with enough air pressure, turn on the electrical power, and step on and off the brake pedal until the low air pressure warning signal comes on

Question 74

What is the purpose of an alcohol evaporator?

Answer 74

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

Question 75

The brake chamber fills with air, pushing the ro out, which moves the ___, which twists the ___.

Answer 75

Slack adjuster; brake camshaft

Question 76

To test the air service brakes,

Answer 76

Brake firmly while slowly moving forward

Question 77

Which is the most important thing to remember about emergency braking?

Answer 77

If the wheels are skidding, you cannot control the vehicle

Question 78

Controlled braking

Answer 78

Is used to keep a vehicle in a straight line when braking

Question 79

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

Answer 79

3 psi in one minute

Question 80

The air compressor stops pumping air at ___ psi

Answer 80

125