Parking & Stopping

Study questions with answers

8 sample Parking & Stopping questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.

1. 1. On newer vehicles, how do you apply the parking (spring) brakes?

   Correct answer: Pull out the yellow, diamond-shaped control knob

   Newer air brake vehicles use a yellow, diamond-shaped push-pull knob; you pull the knob out to set the parking brakes and push it in to release them.

   Source: Alabama Commercial Driver License Manual, Section 5 (Air Brakes) - 5.1.15 Parking Brake Controls

2. 2. On a tractor or straight truck, spring brakes will come fully on when air pressure drops into roughly what range?

   Correct answer: About 20 to 45 psi

   When air pressure falls to about 20 to 45 psi (often between 20 and 30), the springs are no longer held back and the spring brakes apply fully.

   Source: Alabama Commercial Driver License Manual, Section 5 (Air Brakes) - 5.1.14 Spring Brakes

3. 3. With the engine off and a fully charged system, what is the maximum acceptable air loss rate for a single vehicle?

   Correct answer: Less than 2 psi in one minute

   During the leakage test on a fully charged system with the engine off, a single vehicle should lose less than 2 psi in one minute (combination vehicles are allowed less than 3 psi per minute).

   Source: Alabama Commercial Driver License Manual, Section 5 (Air Brakes) - 5.3.3 Final Air Brake Check

4. 4. Why should you avoid pressing the brake pedal while the spring brakes are already applied?

   Correct answer: The combined forces can damage the brakes

   Doing so combines the force of the springs with the air pressure, which can damage the brakes, so it is better never to press the pedal when the spring brakes are on.

   Source: Alabama Commercial Driver License Manual, Section 5 (Air Brakes) - 5.1.15 Parking Brake Controls

5. 5. Why is it important to drain the air tanks completely?

   Correct answer: To remove water and oil that could cause brake failure

   Compressed air carries some water and compressor oil that settle at the bottom of the tank; the water can freeze in cold weather and cause the brakes to fail, so the tanks must be drained.

   Source: Alabama Commercial Driver License Manual, Section 5 (Air Brakes) - 5.1.4 Air Tank Drains

6. 6. With a manually operated tank drain valve, how often must the driver drain the tanks?

   Correct answer: At the end of each day of driving

   A manual drain has to be opened by the driver, and it should be done at the end of each driving day to clear out the collected water and oil.

   Source: Alabama Commercial Driver License Manual, Section 5 (Air Brakes) - 5.1.4 Air Tank Drains

7. 7. How are the powerful springs in spring brakes normally held back while you drive?

   Correct answer: By air pressure holding them off

   During driving, air pressure holds the strong springs back; if that air pressure is lost, the springs are released and put the brakes on.

   Source: Alabama Commercial Driver License Manual, Section 5 (Air Brakes) - 5.1.14 Spring Brakes

8. 8. When is it best NOT to set the parking brakes?

   Correct answer: When the brakes are very hot, or very wet in freezing weather

   Avoid using the parking brakes when the brakes are very hot from coming down a steep grade or very wet in freezing temperatures; heat can damage them and wet brakes can freeze so the vehicle cannot move. Use wheel chocks instead.

   Source: Alabama Commercial Driver License Manual, Section 5 (Air Brakes) - 5.4.8 Parking Brakes