310T Air Brakes and Braking Systems 2

Question 1

What is the purpose of the double-check valve in an air brake system?

Accepted Answer

To allow the higher of two air pressure sources to pass through while blocking the lower

Answer

To regulate air pressure to the rear brakes only

Answer

To prevent air from flowing back into the supply reservoir

Answer

To limit pressure to the spring brake chambers

Question 2

On a tractor-trailer combination, the trailer supply valve (also called the tractor protection valve control) is normally what color?

Accepted Answer

Red

Answer

Blue

Answer

Yellow

Answer

Green

Question 3

What happens to the spring brakes when the parking brake control valve is pushed IN on a truck?

Accepted Answer

Spring brakes release

Answer

Spring brakes apply

Answer

Service brakes apply

Answer

Nothing changes

Question 4

Which component prevents moisture and contaminants from entering the air brake system from the compressor?

Accepted Answer

Air dryer

Answer

Unloader valve

Answer

Wet tank drain

Answer

Pressure protection valve

Question 5

What is the normal cut-in pressure for most air brake system compressors?

Accepted Answer

80–85 psi

Answer

60–70 psi

Answer

100–120 psi

Answer

125–130 psi

Question 6

A technician finds that a brake chamber's stroke is beyond the readjustment limit. What is the MOST likely cause?

Accepted Answer

Worn brake shoes/linings

Answer

Low air pressure in the system

Answer

Defective relay valve

Answer

Cracked brake drum

Question 7

What does a quick-release valve do in an air brake system?

Accepted Answer

Exhausts air locally to speed up brake release

Answer

Quickly charges the reservoirs

Answer

Prevents air loss if a brake line ruptures

Answer

Reduces pressure spikes during hard braking