CLP Air Brake Systems 2 — Questions and Answers
Question 1: What is the purpose of the air compressor governor in an air brake system?
- To regulate the speed of the air compressor motor
- To cut out the compressor when tank pressure reaches the maximum level and cut it in when pressure drops (Correct answer)
- To control the rate at which air flows to the brake chambers
- To prevent the air dryer from freezing in cold weather
Correct answer: To cut out the compressor when tank pressure reaches the maximum level and cut it in when pressure drops
The governor controls the air compressor by cutting it out when tank pressure reaches about 125 psi and cutting it back in when pressure drops to around 100 psi.
Question 2: How does a dual air brake system improve safety compared to a single system?
- It doubles the braking force applied to each wheel
- It provides two separate air systems so that if one fails, the other can still stop the vehicle (Correct answer)
- It allows the driver to apply front and rear brakes independently at all times
- It automatically applies the parking brakes if a leak is detected
Correct answer: It provides two separate air systems so that if one fails, the other can still stop the vehicle
A dual air brake system has two separate air systems — if one system fails, the other still provides enough braking power to stop the vehicle safely.
Question 3: What should you do if the low air pressure warning activates while driving?
- Increase speed to reach the nearest truck stop quickly
- Continue driving but avoid hard braking
- Stop the vehicle safely and as quickly as possible (Correct answer)
- Switch to the secondary air system using the dashboard toggle
Correct answer: Stop the vehicle safely and as quickly as possible
When the low air pressure warning activates, you should stop the vehicle immediately and safely, as braking ability will soon be severely impaired.
Question 4: What is the function of the brake chambers in an air brake system?
- They store compressed air for emergency use
- They convert air pressure into mechanical force to apply the brakes (Correct answer)
- They filter moisture and contaminants from compressed air
- They regulate the pressure sent to each individual wheel
Correct answer: They convert air pressure into mechanical force to apply the brakes
Brake chambers convert compressed air pressure into the mechanical force needed to push the brake shoes against the brake drums.
Question 5: At what approximate air pressure do spring brakes (parking brakes) fully apply on most vehicles?
- 60 psi
- 45 psi
- 20 psi (Correct answer)
- 90 psi
Correct answer: 20 psi
Spring brakes are designed to fully apply when air pressure drops to approximately 20 psi, ensuring the vehicle stops if air is lost.
Question 6: What is brake fade in drum brake systems?
- The gradual wear of brake pads over time
- A loss of braking power caused by heat build-up from prolonged brake use (Correct answer)
- The tendency of brakes to pull to one side when applied
- Air leaking from brake chambers during heavy braking
Correct answer: A loss of braking power caused by heat build-up from prolonged brake use
Brake fade occurs when excessive heat from prolonged braking reduces friction between the brake shoes and drum, resulting in decreased stopping power.
Question 7: What does the air pressure gauge tell the driver during operation?
- The temperature of the compressed air in the tanks
- The pressure in both the primary and secondary air tanks (Correct answer)
- The rate of air leak from the brake lines
- The amount of brake lining remaining on each axle
Correct answer: The pressure in both the primary and secondary air tanks
The air pressure gauge shows the driver the current pressure levels in the primary and secondary air systems so they can monitor system health while driving.
CLP Air Brake Systems 2
What is the purpose of the air compressor governor in an air brake system?