Free CDL Air Brake Dangers and Safety Questions and Answers — Questions and Answers
Question 1: What can cause brake fade or failure?
- Overheating due to excessive braking (Correct answer)
- Insufficient air pressure in the system
- Using the brakes too lightly
- Relying too much on the engine brake
Correct answer: Overheating due to excessive braking
Brake fade occurs when the brakes become excessively hot due to prolonged or heavy use, especially on long descents. This overheating reduces the friction capabilities of the brake components, making them less effective at slowing or stopping the vehicle and potentially leading to complete brake failure.
Question 2: What should you do if your low air pressure warning activates?
- Stop immediately and safely park the vehicle. (Correct answer)
- Keep driving until you find a repair shop.
- Pump the brakes to restore air pressure.
- Activate the parking brake immediately.
Correct answer: Stop immediately and safely park the vehicle.
If the low air pressure warning activates, it indicates a critical issue with the air brake system, meaning there might not be enough air to safely operate the brakes. Continuing to drive risks complete brake failure, so the safest and most responsible action is to immediately and safely stop the vehicle to prevent an accident.
Question 3: How can you avoid brake fade when driving downhill?
- Apply the brakes lightly and continuously.
- Use a lower gear and only apply the brakes when necessary. (Correct answer)
- Pump the brakes rapidly to keep them cool.
- Shift to neutral and rely on service brakes.
Correct answer: Use a lower gear and only apply the brakes when necessary.
To prevent brake fade on downgrades, commercial drivers should use a lower gear to allow the engine to provide braking power, known as engine braking. This technique reduces the reliance on the service brakes, keeping them cooler and ready for when they are truly needed, thus preventing overheating and maintaining braking effectiveness.
Question 4: How often should air tanks be drained?
- Once a week
- At every oil change
- Daily, at the end of each shift (Correct answer)
- Only when you hear water in the system
Correct answer: Daily, at the end of each shift
Air tanks in a commercial vehicle's air brake system collect water and oil contaminants, which can freeze in cold weather or corrode the system. Draining the air tanks daily, at the end of each shift, is crucial to remove these contaminants and ensure the proper functioning and longevity of the air brake system.
Question 5: When should you avoid using the parking brake?
- When the brakes are hot after a long descent. (Correct answer)
- When the vehicle is parked on a steep incline.
- When the air pressure is below 60 psi.
- When parking in freezing temperatures.
Correct answer: When the brakes are hot after a long descent.
Applying the parking brake when the service brakes are hot, especially after a long descent, can cause the brake drums or rotors to warp as they cool unevenly. It can also cause the brake linings to stick to the drums or rotors, potentially damaging the brake system. It's safer to allow hot brakes to cool down before engaging the parking brake.
Free CDL Air Brake Dangers and Safety Questions and Answers
What can cause brake fade or failure?