Commercial Driving Air Brakes 2

Question 1

What is the purpose of drain valves on air brake tanks?

Accepted Answer

To remove accumulated water and oil from the air tanks that could cause brake failure

Answer

To add air to the system

Answer

To check tire pressure

Answer

To release parking brakes

Question 2

How should you test the low air pressure warning?

Accepted Answer

With the engine off, pump the brake pedal to reduce pressure and verify the warning activates before 60 PSI

Answer

Drive the vehicle until brakes fail

Answer

Ask a mechanic to test it

Answer

Low air warnings cannot be tested

Question 3

What is a slack adjuster?

Accepted Answer

A lever mechanism that adjusts the distance between the brake shoes and drum to compensate for wear

Answer

A tool for adjusting mirrors

Answer

A seatbelt tensioner

Answer

A steering alignment tool

Question 4

What is the air brake applied pressure test procedure?

Accepted Answer

Build pressure to operating level, turn off engine, apply the brake, and observe pressure drop — it should not exceed 3 PSI in one minute for single vehicles

Answer

Drive and brake repeatedly

Answer

Listen for air leaks only

Answer

Check the brake fluid level

Question 5

What is the function of the relay valve in an air brake system?

Accepted Answer

To speed up brake application and release on trailers by using local air supply near the brakes

Answer

To relay messages to the driver

Answer

To control the turn signals

Answer

To power the air horn

Question 6

During a pre-trip inspection, how much free play should a manual slack adjuster have?

Accepted Answer

No more than 1 inch

Answer

No more than 2 inches

Answer

Any amount is acceptable

Answer

Exactly 3 inches