Air Brakes

Question 1

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

a. park on a level ground, chock the wheels, release the parking brake when you have enough air pressure and shut the engine off and step on and off the brake pedal
b. Park on a light step, drain the air pressure, apply the parking brake and check for movement
c. park on a level ground, wait for the pressure to build up to normal, release the parking brake, move the truck forward and apply the pedal brake as hard as you can

Answer 1

park on a level ground, chock the wheels, release the parking brake when you have enough air pressure and shut the engine off and step on and off the brake pedal

Question 2

If you don’t have an automatic drain tanks, how often should you drain oil and water that collect at the bottom of the compressed air storage in the air tank?

a. once a week
b. after every 4 hours of service
c. at the end of each day of driving

Answer 2

at the end of each day of driving

Question 3

The air compressor must stop pumping air at:

a. 125 psi
b. 100 psi
c. 150 psi

Answer 3

125 psi

Question 4

To check the slack adjusters on S-cam brakes, you should park on:

a. level ground with parking brake, then apply the service brakes
b. level ground and drain the air pressure before adjust the movement of the vehicle
c. level ground, chock the wheels, and turn off the parking brakes

Answer 4

level ground, chock the wheels, and turn off the parking brakes

Question 5

Tractor and straight truck spring brakes will come fully on when tire pressure drops to:

a. 100 psi
b. 60 psi
c. 20 psi

Answer 5

20 psi

Question 6

The brake system that apply and release the brakes when the driver uses the pedal brake is the:

a. parking brake system
b. emergency brake system
c. service brake system

Answer 6

service brake system

Question 7

The hand brake (parking) or emergency brake in a heavy vehicle can be held in position by something like:

a. parking brake system
b. emergency brake system
c. springs

Answer 7

springs

Question 8

Emergency controlled braking is when:

a. you apply the brakes as hard as you can without locking the wheels
b. apply the brakes as hard as you can, release the brakes when you lock the wheels and apply the brakes again when the wheels start moving
c. apply the hand valve for a second, then apply the brake pedal harder

Answer 8

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

Question 9

A pressure gauge tell you how much air there is in:

a. tractor brake lines
b. trailer brake lines
c. air tanks

Answer 9

air tanks

Question 10

With air brakes there is an added delay than hydraulic brakes because:

a. the air takes more to flow through the lines than hydraulic liquid
b. the air brakes use different brake drums
c. the air brakes require return springs more heavy

Answer 10

the air takes more to flow through the lines than hydraulic liquid

Question 11

Your vehicle has a dual air brake system. If you receive a low air pressure signal of your secondary system, you should:

a. slow down, and drive to the nearest garage to fix it
b. slow down and test your system while you are on the road
c. bring the vehicle to a safe stop and continue only when the system is fixed

Answer 11

bring the vehicle to a safe stop and continue only when the system is fixed

Question 12

Under normal conditions, to turn on the parking brakes, the first thing the driver has to do:

a. you have to be sure the air brake system is fully charges
b. release air from the air brake system
c. turn the engine off

Answer 12

release air from the air brake system

Question 13

All the vehicles equipped with air brakes have:

a. a backup hydraulic system
b. a supply pressure gauge
c. an air use gauge

Answer 13

a supply pressure gauge

Question 14

You should know that your brakes fail when you:

a. release the brake pedal pressure and hen speed up
b. have to apply hard the brake pedal to control your speed on a downgrade
c. apply the brake pedal and it feels spongy when you apply pressure

Answer 14

have to apply hard the brake pedal to control your speed on a downgrade

Question 15

Modern air brake systems use three different systems, they are service, hand (parking), and:

a. foot brakes
b. s-cam brakes
c. emergency brakes

Answer 15

emergency brakes

Question 16

The best way to use the brakes on a long steep downgrade after choosing the proper gear is slowing down until your speed is approximately:

a. 5 miles per hour down your safe speed, then release your brakes
b. 15 miles per hour down your safe speed, then release your brakes
c. 10 miles per hour down your safe speed then release your brakes

Answer 16

5 miles per hour down your safe speed, then release your brakes

Question 17

The total distance to stop with air brakes is longer than hydraulic brakes because:

a. brake lag distance
b. reaction distance
c. effective braking distance

Answer 17

brake lag distance

Question 18

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

a. up the gear shift
b. down the gear shift
c. stop and park safely as soon as possible

Answer 18

stop and park safely as soon as possible

Question 19

A slack adjuster probably needs to be adjusted if it moves more than, approximately:

a. 1/4 of inch when you pull it hard
b. 1 inch when you pull it hard
c. 1/2 inch when you pull it hard

Answer 19

1 inch when you pull it hard

Question 20

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

a. Never
b. If you are doing a pre inspection before you leave
c. if you will be far from the truck only for a few minutes

Answer 20

never

Question 21

Why do you have to drain water from the compressed air tanks?

a. the lower level of boiling water reduce the brake power
b. the water can freeze in cold weather and cause brake failure
c. to prevent the oil of the oil compressor from getting dirty

Answer 21

the water can freeze in cold weather and cause brake failure

Question 22

If the air compressor of your truck may have its own oil supply, when should you check the oil level?

a. before driving
b. immediately after stopping
c. in the first inspection on route

Answer 22

before driving

Question 23

Foundation brake is the most common type that you can find in heavy trucks is:

a. wedge drum
b. s-cam drum
c. disc brake

Answer 23

s-cam drum

Question 24

• **The air loss rate on a truck or a straight bus with the engine off and step on the brake pedal should not be more than:
  a. 3 psi in one minute
  b. 2 psi in 45 seconds
  c. 1 psi in one minute

Answer 24

3 psi in one minute

Question 25

* **An air brake system for truck or a bus should not have leaks more than (engine off and release the brakes): a. 3 psi by minute b. 2 psi by minute c. 1 psi by minute

Answer 25

2 psi by minute

Question 26

Some air brake systems have an evaporator. What could happen if you didn't have the alcohol container filled up? a. it is possible that the s-cam won't rotate back when you release the brake pedal b. the air deposits tanks can freeze and cause brake failure c. brake drums can freeze and it may bend them

Answer 26

the air deposits tanks can freeze and cause brake failure

Question 27

To test the air service brakes, you should: a. push the brake pedal hard when you move forward slowly b. push the brake pedal hard when you move back slowly c. stop the vehicle, put in a low gear, apply the service brake, and gently push agains the brakes

Answer 27

push the brake pedal hard when you move forward slowly

Question 28

If your truck or bus has dual parking control valves, you can use air pressure from a separate air tank to: a. apply more pressure to the brakes if the main tank is low b. balance the service brake system when you are parking c. release the emergency spring brakes/hand brakes to move a short distance

Answer 28

release the emergency spring brakes/hand brakes to move a short distance

Question 29

If your truck has a dual air system and one of the systems has low pressure: a. brake drums are not pressurized totally b. the front or the rear brakes will not be operating fully c. the slack adjusters manual on s-cam brakes are not on

Answer 29

the front or the rear brakes will not be operating fully

Question 30

The safety valve turns on automatically to reduce pressure at: a. 150 psi b. 50 psi c. 100 psi

Answer 30

150 psi

Question 31

If you are driving on a steep downgrade and you reach the 40 mph safety speed, you would apply the service brakes until your speed slows down to: a. 35 mph b. 30 mph c. 25 mph

Answer 31

35 mph

Question 32

For air brake system in good condition, the air compressor should start pumping at: a. 100 psi b. 125 psi c. 150 psi

Answer 32

100 psi

Question 33

If the spring brakes are on, when should you push the break pedal? a. only on a slippery road b. never c. only when you drive on a steep downgrade

Answer 33

never

Question 34

It is not safe to drive a vehicle that has brake drums or discs with cracks longer than: a. 1/4 the width of the friction area b. 3/4 the width of the friction area c. 1/2 the width of the friction area

Answer 34

1/2 the width of the friction area

Question 35

Parking brakes or emergency brakes on trucks and buses can be stopped legally with: a. air pressure b. fluid pressure c. spring pressure

Answer 35

spring pressure

Question 36

If your vehicle has an alcohol evaporator, every day on cold weather, you should: a. check the oil for the alcohol contents b. check the alcohol container and fill it up c. change the alcohol from a new bottle

Answer 36

check the alcohol container and fill it up

Question 37

If your vehicle has a alcohol evaporator: a. this helps to reduce the risk of ice in air brake valves during cold weather b. it eliminates the alcohol moisture in the tank that condense and then to collect in the bottom of the air tank c. eliminate the necessity of drain gin the tank everyday

Answer 37

this helps to reduce the risk of ice in air brake valves during cold weather

Question 38

When you apply the brakes, the brake shoes or lining are pressed against the: a. brake drum or disc b. slack adjuster c. s-cam

Answer 38

brake drum or disc

Question 39

The brake pedal in the air brake system: a. control the air compressor speed b. control the air pressure when you apply the brakes c. it is connected to the slack adjusters

Answer 39

control the air pressure when you apply the brakes

Question 40

If the air pressure doesn't build up to normal fast enough, then: a. the air pressure could drop too low during driving, requiring an emergency stop b. you should be ready to use the parking brake to stop the vehicle c. the alcohol container may be low

Answer 40

the air pressure could drop too low during driving, requiring an emergency stop

Question 41

Vehicles with air brakes, should use their parking brakes: a. when you leave the vehicle alone b. only during inspections before or after the road c. as little as possible

Answer 41

when you leave the vehicle alone

Question 42

There is a suspension picture in the exam. They're leaves in a leaf spring. The question is: If there is one cracked leaf, what is the maximum allowed? a. 1 inch b. 1/4 inch c. 1/2 inch

Answer 42

1/2 inch

Question 43

Which of these is NOT the correct way to put on the brakes: a. if the brakes are too hot, after going down a steep road b. only been stopped for at least one hour c. you are going to check the parking brake to be sure that you can stop the vehicle

Answer 43

if the brakes are too hot, after going down a steep road

Question 44

Excessive use of service brakes results in overheating and could lead to: a. cause expansion of the contact between the brake drums and the brake linings b. expansion of the brake drums c. it can get out of adjustment of the s-cam

Answer 44

expansion of the brake drums

Question 45

The application pressure gauge shows you how much air pressure you: a. have in the air tank b. have in the modulating control valve c. are applying to the brakes

Answer 45

are applying to the brakes

Question 46

If your truck has a dual air brake system, small air tanks and it works correctly, their pressure should build up from 85 psi to 100 psi in: a. 60 sec b. 45 sec c. 30 sec

Answer 46

45 sec

Question 47

During normal driving, the spring brakes are held by: a. spring pressure b. air pressure c. bolts

Answer 47

air pressure

Question 48

The air compressor governor controls: a. when air pumps to the air tanks b. the speed of air compressor c. the air pressure applied to the brakes

Answer 48

when air pumps to the air tanks

Question 49

When is the safety valve usually set to open? a. 150 psi b. 125 psi c. 100 psi

Answer 49

150 psi

Question 50

An air brake system is fully loaded when the tank is: a. 125 psi b. 75 psi c. 100 psi

Answer 50

125 psi

Question 51

When you go on a steep downgrade, and you have to apply your foot hard on the brake pedal to maintain the same speed, this means that your brake is fading, you should: a. slow down and change to a low gear b. maintain the same speed c. slow down and change to a high speed

Answer 51

slow down and change to a low gear

Question 52

A parking brake control in the cab allows the driver to: a. let air out of the spring brakes, and this lets the spring put the brakes on b. control the air of the tanks c. let air out of the brakes, but it doesn't let the springs put the brakes on

Answer 52

let air out of the spring brakes, and this lets the spring put the brakes on

Question 53

What is the valve control modulating? a. start of the retarders b. used to apply the spring brakes gradually c. controls the compressor speed

Answer 53

used to apply the spring brakes gradually

Question 54

Before driving a vehicle with dual air system, allow time for the air compressor to build up the pressure a minimum of: a. 80 psi b. 100 psi c. 125 psi

Answer 54

100 psi

Question 55

The brake drums or discs should not have cracks more than: a. 3/4 of friction area b. 1/2 of friction area c. 1/4 of friction area

Answer 55

1/2 of friction area

Question 56

What are you testing when you wait for normal air pressure, release the parking brake, move the vehicle forward slowly about 5 mph and apply the brakes firmly using the brake pedal? a. parking brakes b. service brakes c. emergency brakes

Answer 56

service brakes

Question 57

The air brake lag distance at 55 mph on dry pavement adds about 32 feet, so under good traction and brake conditions the total stopping distance is over: a. 300 feet b. 100 feet c. 500 feet

Answer 57

300 feet

Question 58

Results from excessive heat, causing chemical changes in the brake lining with reduced friction and also causes expansion of the brakes drums, This is called: a. control brake b. fail or brake fade c. parking brake

Answer 58

fail or brake fade

Question 59

Let hot brakes cool before using the brakes of: a. emergency b. parking c. hand

Answer 59

parking

Question 60

Pressing and releasing the brake pedal unnecessarily can: a. change the air pressure of the brake b. accumulation of air pressure of the brake c. let air go out and reduce the air pressure

Answer 60

let air go out and reduce the air pressure

Question 61

How should you check that the service brakes are working properly? a. Park on a level ground, wait for the pressure to build up to normal and release the parking brake, move the truck forward slowly 5 mph and apply the brake pedal as hard as you can b. park on a light steep, drain the air pressure, apply the parking brakes and check for movement c. park on a level ground, chock the wheels, put on the parking brake, when you have enough air pressure to do it and shut the engine off

Answer 61

Park on a level ground, wait for the pressure to build up to normal and release the parking brake, move the truck forward slowly 5 mph and apply the brake pedal as hard as you can

Question 62

If the service brakes are used too much, they can cause: a. the spring brake lines to fail b. the modulated control valve to fail c. the air brakes to fail

Answer 62

the air brakes to fail

Question 63

What should you do to stop a trailer jackknife? a. countersteer the steering wheel b. use the trailer hand brake c. release the service brakes

Answer 63

release the service brakes

Question 64

The modulated control valve allows you to control: a. the front brakes b. the air pressure amount of the brake system c. the spring brakes

Answer 64

the spring brakes

Question 65

The air brake lag distance at 55 mph on dry pavement adds about: a. 32 feet to the stop distance b. 52 feet to the stop distance c. 72 feet to the stop distance

Answer 65

32 feet to the stop distance

Question 66

What sentence is true about using retarders? a. it creates extra heat between the brake shoes or pads and drums or disks b. brakes used on a steep downgrade increases the engine brake effect c. you should not use the retarder as the principal way of speed control

Answer 66

you should not use the retarder as the principal way of speed control

Question 67

During an hydraulic brake inspection, you should pump the brake pedal three times and then verify that it holds for five seconds, if the brakes are working correctly the pedal should: a. not move b. slightly pressing c. down to the floor

Answer 67

not move

Question 68

You are driving a 40 feet long vehicle at 35 mph. The road is dry and the visibility is good. What is the minimum space you should keep in front of your vehicle to be safe? a. 5 seconds b. 4 seconds c. 3 seconds

Answer 68

4 seconds

Question 69

The power of the brakes of the spring brakes: a. depends of the service brakes to be on adjustment b. is not affected by the service brakes condition c. increases when the service brakes are hot

Answer 69

depends of the service brakes to be on adjustment

Question 70

Using the air brakes on a steep down grade, under normal conditions is only a supplement of: a. using the limiting valve of the front brake b. using the spring brakes c. engine brake effect

Answer 70

engine brake effect

Question 71

If you have to make an emergency stop, brake so: a. you can steer the wheel and keep your vehicle on a straight lane b. using the hand brake first c. you can steer the wheel suddenly and suddenly braking

Answer 71

you can steer the wheel and keep your vehicle on a straight lane

Question 72

``` Appears a figure. (BOLA) that shows part of the brake. What holds that part of the brake? a. screws b. pins c. brackets ```

Answer 72

screws

Question 73

S-Cam a. when you press the brake pedal. the air pressure pushes toward the outside of the dip stick. moving the regulator and twisting the dip stick of the excentric brake b. the push rod of the brake chamber presses spike directly c. use a power bolt

Answer 73

when you press the brake pedal. the air pressure pushes toward the outside of the dip stick. moving the regulator and twisting the dip stick of the excentric brake

Question 74

In the air tank, the low air pressure alarm signal turns on before the pressure decreases to: a. 50 psi b. 60 psi c. 80 psi

Answer 74

60 psi