← CDL Air Brakes – Complete Study Flashcards

Free CDL Air Brakes – Complete Study Flashcards Practice Test (2026)

50 questions · 60 min · 80% to pass

50 Questions · 60 Minutes · 80% to Pass

Question 1 of 5

Sample Questions

Question 1

What does the governor control in an air brake system?

Answer: The governor controls when the air compressor pumps air by cutting out at a set maximum pressure and cutting in again when pressure drops to a minimum level.

Question 2

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

Answer: The air compressor pumps air into the storage tanks to build and maintain the air pressure needed to operate the brakes.

Question 3

At what pressure does the governor typically cut out the air compressor?

Answer: The governor cuts out the air compressor at approximately 125 psi (the cut-out pressure), stopping compression until pressure drops back to the cut-in level.

Question 4

What is the purpose of the safety relief valve in the air tank?

Answer: The safety relief valve opens to release air if the pressure in the tank exceeds the maximum safe level (usually 150 psi), protecting the system from over-pressurization.

Question 5

What is the function of the air dryer in an air brake system?

Answer: The air dryer removes moisture and contaminants from the compressed air before it enters the storage tanks, preventing freeze-ups and corrosion.