ELDT ELDT - Entry Level Driver Training Air Brakes Questions and Answers 1

Question 1

What is the minimum air pressure required before driving a vehicle equipped with air brakes?

Accepted Answer

100 psi

Answer

FMCSA requires air pressure to reach at least 100 psi before a CMV with air brakes can be driven.

Question 2

What does the low air pressure warning activate in most air brake systems?

Accepted Answer

A warning light and/or buzzer

Answer

A warning light and/or buzzer activates when air pressure drops to around 60 psi, alerting the driver to stop safely.

Question 3

What is the purpose of the air compressor governor in an air brake system?

Accepted Answer

To control when the compressor cuts in and cuts out

Answer

The governor controls the air compressor, causing it to cut out around 125 psi and cut back in around 100 psi.

Question 4

During the static air leakage test, what is the maximum allowable air pressure drop per minute for a combination vehicle?

Accepted Answer

3 psi

Answer

For a combination vehicle, air pressure should not drop more than 3 psi per minute with the engine off and brakes released.

Question 5

What type of brakes are spring brakes designed to act as?

Accepted Answer

Emergency and parking brakes

Answer

Spring brakes are designed to serve as emergency and parking brakes, engaging automatically when air pressure is lost.

Entry Level Driver Training (ELDT) Practice Test