Air Brakes

Front 1

Under normal conditions in order to engage the parking brakes driver:

Back 1

Let the air out of air brake system

Front 2

Air braking takes more time than hydraulic braking because air:

Back 2

Takes more time to flow through the lines than hydraulic fluid

Front 3

The applicator pressure gauge shows how much air pressure you:

Back 3

Are applying to the brakes

Front 4

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

Back 4

20

Front 5

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

Back 5

Ice may form in the air storage tank and cause a brake failure

Front 6

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?

Back 6

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

Front 7

Why drain water from compressed air tanks?

Back 7

Water can freeze in cold weather and cause brake failure

Front 8

The safety valve is set automatically when pressure is:

Back 8

150

Front 9

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

Back 9

Either the front or back brake will not be fully operational

Front 10

Parking or emergency brakes of trucks and buses can be legally held on by_____pressure

Back 10

Spring

Front 11

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

Back 11

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

Front 12

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 100psi within how many seconds?

Back 12

45

Front 13

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

Back 13

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

Front 14

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 released

Back 14

2

Front 15

During normal driving, spring brakes are usually held back by

Back 15

Air pressure

Front 16

The air compressor stops pumping air at what psi?

Back 16

125

Front 17

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

Back 17

60

Front 18

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

Back 18

Expansion of the brake drums

Front 19

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

Back 19

S cam drum

Front 20

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

Back 20

Can steer and so your vehicle stays in a straight line

Front 21

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

Back 21

Check and fill the alcohol level

Front 22

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

Back 22

3 psi in one minute

Front 23

The braking power of the spring brakes:

Back 23

Depends on the service brakes being in adjustment

Front 24

The air brake lag distance at 55mph on dry pavement adds about____ft

Back 24

32

Front 25

Total stopping distance for air brakes is longer than that for hydraulic brakes due to_____distance

Back 25

Brake lag

Front 26

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

Back 26

Brake to fade or fail

Front 27

Repeatedly partially releasing and pressing the brake pedal may result in:

Back 27

A loss of brake air pressure

Front 28

The brake system that applies and releases the brakes when the driver uses the brake pedal is the___Brake system

Back 28

Service

Front 29

A slack adjusters free play needs to be adjusted if it is more than about___how many inches when you pull hard on it?

Back 29

1 inch

Front 30

An air brake system is fully charged at what psi?

Back 30

125

Front 31

The brake pedal in an air brake system:

Back 31

Control the air pressure applied to put on the brakes

Front 32

The s cam:

Back 32

Forces the brake shoes against the inside of the brake drum

Front 33

All air brake equipped vehicles have

Back 33

A supply pressure gauge

Front 34

With air brake vehicles, the parking brakes should be used:

Back 34

Whenever you leave the vehicle unattended

Front 35

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

Back 35

To brake vehicle very hard, in other word when coming down the steep grade

Front 36

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

Back 36

Never

Front 37

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

Back 37

Level ground, chock the wheels and release the parking brakes

Front 38

The use of brakes on a long and steep downgrade under normal conditions is only a supplement to:

Back 38

The braking effect of the engine

Front 39

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

Back 39

Stop and safely park as soon as possible

Front 40

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

Back 40

Spring pressure

Front 41

When brakes are applied the brake shoe will press against the:

Back 41

Brake drum or disc

Front 42

The safety valve discharges automatically at the pressure of:

Back 42

150

Front 43

Emergency stab braking is:

Back 43

Press on the brake pedal as hard as you can, release the brakes when the wheels locked, put on the brakes again when the wheels start rolling

Front 44

If air pressure is not built up within the correct amount of time, then:

Back 44

Your air pressure may drop to a low point while driving, requiring an emergency stop

Front 45

The safety valve reduces pressure at___psi

Back 45

150

Front 46

The supply pressure gauge shows how much pressure:

Back 46

Is in the air tanks

Front 47

Your brakes are fading when:

Back 47

You have to push harder on a brake pedal to control your speed on a downgrade

Front 48

The air compressor governor controls:

Back 48

When air is pumped into the air tanks

Front 49

Modern air brake system combine three different systems. They are the service, the parking, and the_____

Back 49

Emergency brakes

Front 50

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___mph below the posted speed for your safety and release your brake.

Back 50

5

Front 51

In ideal conditions a truck or bus with an air brake going at 55 mph would require stopping distance of how many feet?

Back 51

More than 300ft

Front 52

The stop light switch:

Back 52

Turns on your brake lights to warn drivers behind you

Front 53

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

Back 53

1/2

Front 54

To test air service brakes you should:

Back 54

Brake firmly while slowly moving forward