Safe Driving Practices

Study questions with answers

12 sample Safe Driving Practices questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.

1. 1. When checking governor cut-in and cut-out during the final air brake check, at about what pressures should the compressor start and stop?

   Correct answer: Start near 100 psi and stop near 125 psi

   Pumping should begin around 100 psi and cut out near 125 psi; check the maker's specs, since a faulty governor may not hold enough air for safe driving.

   Source: Section 5.3.3 - Final Air Brake Check

2. 2. With the foot brake fully applied and the engine off, how much may a single vehicle's air pressure drop in one minute before the leak is excessive?

   Correct answer: More than three psi is too much

   Holding the foot brake down for a minute, a single vehicle losing more than three psi (or a combination more than four) has too much leakage and must be fixed before driving.

   Source: Section 5.3.3 - Final Air Brake Check

3. 3. How are the emergency and parking (spring) brakes held off while you drive?

   Correct answer: Air pressure holds the powerful springs back

   During driving, air pressure keeps the strong springs compressed; if that air escapes, the springs apply the brakes, which is why a major leak sets the spring brakes.

   Source: Section 5.1.14 - Spring Brakes

4. 4. Does ABS shorten your stopping distance?

   Correct answer: Not necessarily, but it helps you stay in control during hard braking

   ABS may not reduce how far you need to stop, but it keeps the vehicle controllable during hard braking so you can steer around trouble.

   Source: Section 5.1.16 - Antilock Braking Systems (ABS)

5. 5. What does an alcohol evaporator do for an air brake system?

   Correct answer: It helps keep ice from forming in the valves during cold weather

   By adding alcohol to the air, the evaporator lowers the chance of ice forming in the valves and other components in cold weather, though daily tank draining is still needed.

   Source: Section 5.1.5 - Alcohol Evaporator

6. 6. At what pressure is the air brake safety relief valve usually set to open?

   Correct answer: 150 psi

   Mounted in the first tank the compressor fills, the relief valve normally opens at 150 psi to guard against over-pressure; if it vents air, have a mechanic look at it.

   Source: Section 5.1.6 - Safety Valve

7. 7. How should you test the service brakes before starting a trip?

   Correct answer: Roll forward slowly and press the pedal firmly, noting any pull or delay

   At about five mph with normal pressure and the parking brake off, apply the brakes firmly and watch for pulling to one side, an odd feel, or a slow response.

   Source: Section 5.3.3 - Final Air Brake Check

8. 8. Why can needlessly pumping the brake pedal be dangerous on an air brake vehicle?

   Correct answer: It can bleed off air faster than the compressor rebuilds it

   Each release lets a little air escape, so pointless pumping can bleed pressure off faster than the compressor rebuilds it, and if it drops too far the brakes quit.

   Source: Section 5.1.7 - The Brake Pedal

9. 9. What is the main job of the air compressor on an air brake vehicle?

   Correct answer: To pump air into the storage tanks

   The compressor supplies the system by forcing air into the storage reservoirs; it draws its power from the engine through a belt or a set of gears.

   Source: Section 5.1.1 - Air Compressor

10. 10. How do you test the parking brake during the air brake inspection?

    Correct answer: Set the parking brake, then ease forward against it in low gear

    With the parking brake set, ease the vehicle forward against it in a low gear to confirm that it holds.

    Source: Section 5.3.3 - Final Air Brake Check

11. 11. What produces the friction that slows an s-cam drum brake, and what side effect does it create?

    Correct answer: The shoes and linings pressing against the drum, which also produces heat

    When the shoes and linings press on the inside of the drum they create the friction that slows the wheel, and that friction also generates heat; too much heat can stop the brakes working.

    Source: Section 5.1.8 - Foundation Brakes

12. 12. Which statement about ABS and your normal brakes is correct?

    Correct answer: It is an add-on that does not change your normal braking ability

    ABS is added on top of the regular brakes and neither increases nor decreases your normal braking power; it engages only when a wheel is about to lock.

    Source: Section 5.1.16 - Antilock Braking Systems (ABS)