Question 1

Your air tanks have manual drain valves, not automatic drains. How often should you drain the water and oil from the tanks?

Accepted Answer

At the end of each day of driving

Question 2

What does the air compressor governor control?

Accepted Answer

When air is pumped into the air tanks

Question 3

If you pull hard on a slack adjuster and it moves more than ___ where the push rod attaches to it, it needs to be adjusted.

Accepted Answer

1 inch

Question 4

During the air brake check, the air pressure builds up too slowly. What can happen?

Accepted Answer

Air pressure may drop to a low point while driving, requiring an emergency stop.

Question 5

Air pressure can leak away over time, so parking and emergency brakes need mechanical force to hold them on. What supplies that mechanical force?

Accepted Answer

Spring pressure

Question 6

Using your brakes too much makes them very hot. What can this excessive heat cause?

Accepted Answer

Brakes to fade or fail

Question 7

At about what pressure, in psi, does the governor stop the air compressor from pumping air?

Accepted Answer

125 psi

Question 8

In an air brake system, which system applies and releases the brakes when you press the brake pedal during normal driving?

Accepted Answer

Service

Question 9

A safety relief valve is usually set to open and let air out when tank pressure reaches ___ psi.

Accepted Answer

150

Question 10

What happens if your vehicle's brake drums overheat?

Accepted Answer

They expand.

Question 11

Why is it important to remove water from the compressed air tanks?

Accepted Answer

Water can freeze in cold weather and cause brake failure.

Question 12

You are going down a long, steep hill at your safe speed of 40 mph. You apply the brakes until your speed drops to _____ mph, then release them.

Accepted Answer

35

Question 13

Using the service brakes too much makes them overheat. This heat can cause ___

Accepted Answer

Expansion of the brake drums

Question 14

Your truck has a dual air brake system and minimum-size air tanks. The engine is at operating rpm. At most, how long should the air pressure take to build from 85 to 100 psi?

Accepted Answer

45 seconds

Question 15

On a vehicle with air brakes, what is a "wig wag"?

Accepted Answer

A mechanical arm that signals low air pressure

Question 16

Which statement about the braking power of spring brakes is correct?

Accepted Answer

It depends on the service brakes being in adjustment.

Question 17

On a newer vehicle with air brakes, how do you apply the parking brakes?

Accepted Answer

Pull the parking brake control knob out.

Question 18

On a straight truck, the spring brakes will be fully on by the time air pressure drops to ___ psi.

Accepted Answer

20

Question 19

What does the stop light switch do on a vehicle with air brakes?

Accepted Answer

It makes the brake lights come on when you use the air brakes.

Question 20

On a vehicle with air brakes, which type of foundation brake is the most common?

Accepted Answer

S-cam drum brake

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