Air Brake System

Question 1

What pumps air into the air storage

tanks?

Answer 1

Air Compressor

Question 2

What controls when the air compressor will

pump air into the air storage tanks?

Answer 2

Air Compressor Governor

Question 3

What is the normal psi range for an air compressor?

Answer 3

100-125 psi

Question 4

What holds the air in an air brake system?

Answer 4

Air Storage Tanks

Question 5

What helps prevent the build up of water and oil in the air compressor?

Answer 5

Air Tank Drains

Question 6

When should the air tank drains be drained?

Answer 6

At the end of every shift.

Question 7

What device helps to
reduce the risk of ice in air brake valves and other
parts during cold weather?

Answer 7

Alcohol Evaporator

Question 8

What device protects the tank and the rest of the system from too much pressure?

Answer 8

Safety Valve

Question 9

What gives a visual of how much air pressure is in the air storage tanks?

Answer 9

Supply Pressure Gage

Question 10

What shows how much air pressure you are

applying to the brakes?

Answer 10

Application Pressure Gauge

Question 11

What switches on during emergency and parking braking, when air pressure is absent?

Answer 11

Spring Brakes

Question 12

Why must air tanks be drained?

Answer 12

To prevent blockages in the tank from frozen liquid during cold weather and to prevent air brake malfunction from excess water and oil.

Question 13

All vehicles with air brakes must have a low air pressure warning signal. True or False?

Answer 13

True

Question 14

Front wheel brakes are good under all conditions. True or False?

Answer 14

True

Question 15

How do you know if your vehicle is equipped with antilock brakes?

Answer 15

The vehicle certification label will indicate if the vehicle is equipped with antilock brakes. It is likely equipped with ABS if it is a truck tractor built after March 1, 1997 or other air brake vehicle built after March 1, 1998.

Question 16

At what pressure does the low air pressure signal turn on?

Answer 16

Under 60 psi

Question 17

At what pressure do the spring brakes switch on?

Answer 17

Typically 20-30 psi

Question 18

What are front brake limiting valves used for?

Answer 18

To reduce the chance of the front wheels

skidding on slippery surfaces.

Question 19

What system has two separate air brake systems, which use a single set of brake controls?

Answer 19

Dual air brake system, one each for the front and rear axle. Also supplies air to trailer.

Question 20

Before driving a vehicle with a dual air system what should you do?

Answer 20

Allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems.

Question 21

What is the device that turns the camshaft and the s-cam when air pressure is applied to the attached rod?

Answer 21

Slack adjuster

Question 22

How do you check the slack adjustors?

Answer 22

a) Park on level ground, being sure to chock each tire.
b) Release the parking brake.

c) Pull hard on each slack adjustor to check for give. (If
it shifts more than an inch, it needs to be adjusted.)

Question 23

How can you test the low-pressure warning signal?

Answer 23

a) Once the air pressure has reached 125 psi, turn the
engine off.

b) Turn on power and apply the brake to release air
pressure.

c) If the warning signal does not come on before the
pressure drops below 60 psi, it needs to be fixed.

Question 24

How can you check that the spring brakes come on automatically?

Answer 24

a) With engine off and power on, repeatedly apply the
service brake to lower air pressure.

b) The tractor protection valve and the parking valve
should pop out when the pressure drops to about 20-
45 psi.

Question 25

What are the maximum leakage rates?

Answer 25

The maximum air leakage rate for a tractor is 2 psi/min and 3 psi/min for a tractor trailer. 

Question 26

Why should you be in the proper gear before starting down a hill?

Answer 26

It is important to use to take advantage of the slowed down engine over solely using brakes to slow down when descending a hillside. This is because overuse of the service brakes can cause overheating resulting in brake fade, which will reduce the efficacy of the brakes stopping power. 

Question 27

What factors can cause brakes to fade or fail?

Answer 27

When the service brakes are overused the brakes can overheat resulting in brake fade. Additionally, when some of the brakes are not properly adjusted the properly adjusted brakes will be forced to overcompensate causing them to overheat and result in brake fade. 

Question 28

The use of brakes on a long, steep downgrade is only a supplement to the braking effect of the engine. True or False?

Answer 28

True.

Question 29

If you are away from your vehicle only a short time, you do not need to use the parking brake. True or False?

Answer 29

False.

Question 30

How should you brake when you drive a tractor-trailer combination with ABS?

Answer 30

Use the service brakes only when needed to maintain control and to stop the vehicle. When slowing be sure to monitor the trailer and slowly reduce pressure applied to the brake pedal. 

Question 31

You still have normal brake functions if your ABS is not working. True or False?

Answer 31

True.