Handling Emergencies

Study questions with answers

10 sample Handling Emergencies questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.

1. 1. How are the powerful springs in spring brakes kept from applying while you drive?

   Correct answer: Air pressure holds them back, and losing that air lets them apply

   Air pressure holds the springs back as you drive; if that air is lost, the springs set the brakes.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.1.14 - Spring Brakes

2. 2. Why is it a bad idea to repeatedly press and release the brake pedal when it isn't necessary?

   Correct answer: It can let air out quicker than the compressor restores it, risking loss of braking

   Needlessly working the pedal bleeds air out faster than the compressor can rebuild it, and if pressure gets too low you lose braking.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.1.7 - The Brake Pedal

3. 3. Which sequence correctly describes stab braking?

   Correct answer: Brake hard, release when the wheels lock, then reapply fully as they begin rolling

   Stab braking is braking hard, releasing the moment the wheels lock, then fully reapplying once the wheels start rolling again.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.4.3 - Emergency Stops

4. 4. After you release the brakes during stab braking, about how long can it take for the wheels to start rolling again?

   Correct answer: As much as one second

   After releasing, it can take as much as a second for the wheels to begin rolling again.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.4.3 - Emergency Stops

5. 5. Why can a heavily loaded vehicle take a long distance to stop once the spring brakes apply?

   Correct answer: The spring brakes work on only some of the axles

   A heavy vehicle stops slowly on spring brakes because those brakes act on only some of the axles.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.4.7 - Low Air Pressure

6. 6. What describes the 'controlled braking' method for an emergency stop?

   Correct answer: Brake as firmly as you can without locking the wheels, using only small steering inputs

   Controlled braking means braking as hard as you can short of locking the wheels while keeping steering inputs small.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.4.3 - Emergency Stops

7. 7. If the ABS warning lamp shows the system has failed, what is true about your brakes?

   Correct answer: Your regular brakes still work; get the ABS repaired soon

   A failed ABS still leaves you with your normal brakes; keep driving carefully and have it serviced soon.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.4.2 - Braking with Antilock Brakes

8. 8. On some buses, what is the separate air tank tied to the parking-brake system used for?

   Correct answer: Releasing the spring brakes briefly so the vehicle can be moved

   The separate tank lets you release the spring brakes long enough to move the vehicle a short distance in an emergency.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.1.15 - Parking Brake Controls

9. 9. When the low-air warning first comes on, what should you do?

   Correct answer: Stop safely right away, while you still have brake control

   As soon as the low-air warning first appears, bring the vehicle to a safe stop while you can still control the service brakes.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.1.14 - Spring Brakes

10. 10. On a tractor or straight truck, spring brakes apply fully once air pressure falls into what range?

    Correct answer: 20 to 45 psi

    On a tractor or straight truck the spring brakes come fully on when pressure drops into the 20 to 45 psi range.

    Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.1.14 - Spring Brakes