Arkansas CDL — Air Brakes: Handling Emergencies Practice Test

Question 1

With the controlled braking method, how hard do you press the brakes?

Accepted Answer

Firmly, but short of the point where the wheels lock — Controlled braking means pressing the brakes with maximum force short of locking the wheels, while keeping steering movements very small. If the wheels lock or you need a bigger steering correction, release and reapply as soon as you can.

Answer

All the way down, releasing only after the wheels lock

Answer

Just hard enough to feel a slowdown, for about three seconds

Answer

Lightly, letting the engine do all the stopping

Question 2

Partway through a trip, your air compressor quits. What can you still count on from the air already stored in the tanks?

Accepted Answer

Enough air to use the brakes several times — The storage tanks are sized so the brakes can still be applied several times after the compressor stops. That reserve is limited, so it covers a few applications, not normal driving.

Answer

Normal braking for the rest of the trip, since the tanks refill themselves

Answer

Nothing at all, because the brakes fail the moment the compressor stops

Answer

Enough air to keep the spring brakes released for as long as you need

Question 3

You keep driving after the low air warning comes on, and tank pressure keeps dropping. On a typical tractor or straight truck, around what pressure will the spring brakes come fully on?

Accepted Answer

Typically between 20 and 30 psi — Tractor and straight truck spring brakes come fully on somewhere in the 20 to 45 psi range, usually 20 to 30 psi. The manual says not to wait for that: stop safely as soon as the warning comes on, while the brakes are still under your control.

Answer

Around 55 psi, the moment the warning comes on

Answer

Around 80 to 85 psi

Answer

Only at 0 psi, once the tanks are empty

Question 4

While stab braking, you release the pedal after the wheels lock, then jam it down again before the wheels have started turning. What is the result?

Accepted Answer

The vehicle will not straighten out — After you let off, locked wheels can take up to one second to start rolling. Reapplying before they turn keeps the vehicle from straightening out, so wait for the wheels to roll before braking fully again.

Answer

The ABS lamp comes on

Answer

The vehicle stops in a shorter distance

Answer

The spring brakes release

Question 5

In a dual air brake system, the low air warning must come on before pressure drops below 55 psi in which system?

Accepted Answer

In either system — The light and buzzer should come on before air pressure falls below 55 psi in either the primary or the secondary system. If that happens while you are driving, stop right away and park safely.

Answer

Only in the primary system

Answer

Only in the secondary system

Answer

Only when both systems drop together

Question 6

What form does the low air pressure warning usually take in the cab?

Accepted Answer

A red light, sometimes with a buzzer — The low air pressure warning is usually a red light, and a buzzer may sound along with it. Some vehicles use a wig wag instead.

Answer

A yellow light that blinks only when the truck is parked

Answer

A green light that goes out when pressure is low

Answer

A horn that sounds outside the vehicle

Question 7

Your truck has a dual air system, and its low air warning has quietly stopped working. A slow leak develops. What are you likely to discover when you brake?

Accepted Answer

It takes longer to stop, and only limited braking is possible before the spring brakes come on — Without a working warning you could lose air without knowing it. In a dual system that means longer stopping distances and only limited braking before the spring brakes apply; in a single-circuit system it could mean sudden emergency braking.

Answer

Nothing changes, because the second system makes up the difference completely

Answer

The brakes lock instantly on every axle

Answer

The ABS takes over and keeps braking normal

Question 8

You must brake hard to avoid a stalled car, and your truck's ABS is working. What should ABS let you do that locked wheels would not?

Accepted Answer

Steer around the obstacle while you are braking — ABS senses wheels about to lock and eases the braking pressure so you stay in control. You may not stop any sooner, but you keep the ability to steer around something while braking, and over-braking skids are avoided.

Answer

Always stop in half the usual distance

Answer

Take your foot off the brake and let ABS stop the truck

Answer

Brake without watching your mirrors

Question 9

Someone suddenly pulls out in front of your air-braked truck. What should your braking aim to do?

Accepted Answer

Keep the vehicle traveling straight while leaving you able to turn if you must — Hitting the brakes is a good response only if there is room and you brake correctly. The manual says to brake so the vehicle stays straight and you can still turn, using controlled braking or stab braking.

Answer

Stop the truck as fast as possible, even if the wheels stay locked

Answer

Bring the spring brakes on with the parking brake knob

Answer

Pump the pedal rapidly while turning sharply

Arkansas CDL — Air Brakes: Handling Emergencies practice test

Study questions with answers

1. With the controlled braking method, how hard do you press the brakes?

2. Partway through a trip, your air compressor quits. What can you still count on from the air already stored in the tanks?

3. You keep driving after the low air warning comes on, and tank pressure keeps dropping. On a typical tractor or straight truck, around what pressure will the spring brakes come fully on?

4. While stab braking, you release the pedal after the wheels lock, then jam it down again before the wheels have started turning. What is the result?

5. In a dual air brake system, the low air warning must come on before pressure drops below 55 psi in which system?

6. What form does the low air pressure warning usually take in the cab?

7. Your truck has a dual air system, and its low air warning has quietly stopped working. A slow leak develops. What are you likely to discover when you brake?

8. You must brake hard to avoid a stalled car, and your truck's ABS is working. What should ABS let you do that locked wheels would not?

9. Someone suddenly pulls out in front of your air-braked truck. What should your braking aim to do?

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