CLP Air Brake Systems 3

Question 1

What is the correct technique for braking on a long, steep downgrade with air brakes?

Accepted Answer

Apply brakes firmly to reduce speed by about 5 mph, release, then reapply as needed

Answer

Apply brakes hard at the top and ride them all the way down

Answer

Use a light, steady brake application throughout the descent

Answer

Put the transmission in neutral to reduce engine resistance and brake continuously

Question 2

What does a properly functioning air dryer do in an air brake system?

Accepted Answer

Removes moisture and contaminants from compressed air before it reaches the tanks

Answer

Cools the compressed air before it enters the brake chambers

Answer

Increases air pressure to compensate for system leaks

Answer

Automatically drains the air tanks every 8 hours

Question 3

How much air pressure loss per minute is acceptable for a combination vehicle during the static leakage test with brakes released?

Accepted Answer

5 psi or less

Answer

3 psi or less

Answer

1 psi or less

Answer

8 psi or less

Question 4

What is the role of the S-cam in a drum air brake system?

Accepted Answer

It rotates to force the brake shoes outward against the brake drum when brakes are applied

Answer

It regulates the amount of air sent to each brake chamber

Answer

It connects the air chamber push rod to the slack adjuster

Answer

It prevents the brakes from locking up during hard stops

Question 5

Why should you never push down the brake pedal to release spring brakes (parking brakes) when there is no air pressure?

Accepted Answer

There is no air pressure to compress the springs, so the service brake pedal cannot release them

Answer

It will damage the foot valve and require expensive repairs

Answer

Doing so will cause the trailer brakes to apply simultaneously

Answer

It bypasses the ABS system and creates a skid risk

Question 6

What is a slack adjuster, and when does it need adjustment?

Accepted Answer

A mechanical arm that adjusts the distance between brake shoes and drum; needs adjustment when push rod travel exceeds limits

Answer

A valve that adjusts air pressure to match vehicle load; adjusted at every oil change

Answer

An electronic sensor that monitors brake pad wear; replaced when warning light activates

Answer

A spring-loaded device that adjusts pedal height for different drivers

Question 7

What happens to the emergency brakes on a trailer if the trailer breaks away from the tractor?

Accepted Answer

The trailer's spring brakes automatically apply due to the loss of air supply

Answer

Nothing — trailer brakes are controlled only from the cab

Answer

The trailer coasts freely until it comes to rest

Answer

The trailer ABS system activates and brings it to a controlled stop