Handling Emergencies

Study questions with answers

8 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. The low-air warning light and buzzer have just come on while you are driving. What is the safest response?

   Correct answer: Get the vehicle safely parked immediately, while you can still manage the brakes

   Act at the first warning and get parked safely while the tanks still have air, rather than waiting for the spring brakes to grab on their own, possibly in a bad spot.

   Source: Arizona CDL Manual — Section 5.1.14: Spring Brakes

2. 2. Which description matches the 'stab' method of emergency braking?

   Correct answer: Press the brakes fully, release when the wheels lock, then reapply fully once they roll again

   Stab braking means full application, release the moment the wheels lock, then full application again once they start rolling; it can take up to a second for the wheels to roll after you let off.

   Source: Arizona CDL Manual — Section 5.4.3: Emergency Stops

3. 3. Why can a heavily loaded truck need a long distance to stop once the spring brakes apply on their own?

   Correct answer: The spring brakes do not act on every axle

   Spring brakes are not fitted to every axle, so a heavy load can take a long way to stop when they come on; that is why you should stop early while foot-brake air remains.

   Source: Arizona CDL Manual — Section 5.4.7: Low Air Pressure

4. 4. How do spring brakes hold a parked vehicle in place?

   Correct answer: Powerful springs apply the brakes once the air holding them back is released

   While you drive, air pressure holds strong springs back; releasing that air, with the parking control or through a leak, lets the springs push the brakes on.

   Source: Arizona CDL Manual — Section 5.1.14: Spring Brakes

5. 5. What is the purpose of a modulating control valve on the dash of some air-braked vehicles?

   Correct answer: To let the driver apply the spring brakes gradually if the service brakes fail

   A modulating valve is spring-loaded for feel and applies the spring brakes more firmly the farther you move the lever, giving you a way to stop if the service brakes fail; lock it fully when parking.

   Source: Arizona CDL Manual — Section 5.1.15: Parking Brake Controls

6. 6. Some buses have a separate air tank tied to a dual parking control valve. What important limit applies to it?

   Correct answer: It holds only enough air to release the spring brakes a few times, so plan your moves

   Pushing the second valve in uses air from a small separate tank to free the spring brakes so you can reposition in an emergency, but there is only enough for a few releases before it runs out.

   Source: Arizona CDL Manual — Section 5.1.15: Parking Brake Controls

7. 7. What defines the 'controlled braking' method during an emergency stop?

   Correct answer: Braking as hard as possible without locking the wheels, with only small steering movements

   In controlled braking you apply as much pressure as you can short of lockup and keep steering inputs tiny; if the wheels lock or you must steer more, release and reapply promptly.

   Source: Arizona CDL Manual — Section 5.4.3: Emergency Stops

8. 8. On a tractor or straight truck, spring brakes will apply by themselves once air pressure falls into roughly what range?

   Correct answer: 20 to 45 psi

   Spring brakes come fully on somewhere between 20 and 45 psi, often 20 to 30, but you should stop safely as soon as the low-air warning appears rather than waiting for them.

   Source: Arizona CDL Manual — Section 5.1.14: Spring Brakes