CDL Air Brake Brake Fade and Downgrade Driving

Question 1

What is brake fade?

Accepted Answer

The loss of braking power caused by overheated brakes

Answer

A gradual increase in braking efficiency over time

Answer

The automatic adjustment of brake pressure on hills

Answer

The reduction in stopping distance on wet roads

Question 2

What is the correct technique for driving down a long, steep grade with air brakes?

Accepted Answer

Select a low gear before starting down and use controlled, intermittent brake applications

Answer

Ride the brakes continuously while staying in a higher gear

Answer

Use only the engine brake and avoid the air brakes entirely

Answer

Shift to neutral to save fuel and use brakes as needed

Question 3

What is 'snub braking' when used on a downgrade?

Accepted Answer

Applying brakes firmly to reduce speed by about 5 mph, then releasing until speed rises again

Answer

Pumping the brakes rapidly to build air pressure

Answer

Using only trailer brakes on steep grades

Answer

Applying maximum brake pressure continuously throughout the descent

Question 4

What is a safe speed limit when driving down a long, steep grade?

Accepted Answer

A speed at which you could still control the vehicle if brakes failed completely

Answer

The posted speed limit for the grade

Answer

5 mph above the speed you could manage without brakes

Answer

55 mph regardless of grade steepness

Question 5

How does brake fade affect stopping distance?

Accepted Answer

Stopping distance increases significantly as brakes overheat

Answer

Stopping distance decreases as brakes get hotter

Answer

Stopping distance remains the same regardless of temperature

Answer

Stopping distance only changes on wet roads

Question 6

What is 'glazing' in the context of brake drums?

Accepted Answer

A smooth, hard surface that forms on overheated brake drums, reducing friction

Answer

Applying a protective coating to brake drums

Answer

Ice formation on brake drums in cold weather

Answer

The normal wear pattern on new brake drums