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. When the low air pressure warning first activates, what is the correct action?

   Correct answer: Get the vehicle safely stopped immediately, while the service brakes still respond

   Do not wait for the spring brakes to set on their own; stop safely at once, while you still have control of the service brakes.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.1.14 - Spring brakes

2. 2. Which sequence describes the stab braking method?

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

   Stab braking means fully applying the brakes, letting off when the wheels lock, and reapplying fully once they start rolling again.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.4.3 - Stab braking

3. 3. In stab braking, why must you wait for the wheels to start rolling before reapplying the brakes?

   Correct answer: Reapplying before the wheels roll keeps the vehicle from straightening out

   It can take up to a second for the wheels to roll again, and reapplying too soon keeps the vehicle from straightening out.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.4.3 - Stab braking

4. 4. When may you fully apply the brakes during an emergency stop?

   Correct answer: When you always drive a vehicle with working ABS on all axles

   The single exception applies only if every vehicle you drive is a straight truck or combination whose ABS works on all axles; in that case an emergency stop may use the brakes fully.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.4.2 - Braking with antilock brakes

5. 5. Why is it risky to let the spring brakes set themselves instead of stopping under control first?

   Correct answer: A light load or slick road can skid, and a heavy load stops slowly since the springs miss some axles

   A light load or a slick road can skid out of control when the springs grab, and a heavy load stops slowly because the spring brakes do not act on every axle.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.4.7 - Low air pressure

6. 6. How do you use the controlled braking method in an emergency?

   Correct answer: Brake as hard as possible short of locking the wheels, with only small steering movements

   Press the brakes about as firmly as possible while stopping just short of a wheel lockup, keeping steering inputs tiny; release and reapply if a wheel locks or you need to steer more.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.4.3 - Controlled braking

7. 7. If you keep driving after the low air warning comes on, what limits your braking?

   Correct answer: Controlled braking works only while air remains, and the spring brakes set at 20 to 45 psi

   You can only brake in a controlled way while air remains in the tanks, and the spring brakes will set once pressure drops to the 20-to-45 psi range.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.4.7 - Low air pressure

8. 8. If the ABS on your vehicle stops working, what braking do you still have?

   Correct answer: Your normal service brakes still work

   ABS is an add-on; when it fails you keep your ordinary service brakes and should just drive normally and get it serviced.

   Source: Wisconsin Commercial Driver's Manual (BDS356), Section 5.1.16 - Antilock braking systems (ABS)