Rhode Island CDL — Air Brakes: Handling Emergencies Practice Test

Question 1

Only your trailer has ABS. While braking, the tractor starts to jackknife and you are losing steering control. What should you do?

Accepted Answer

Let up on the brakes, if safe, until you regain control — With ABS only on the trailer, the trailer is less prone to swinging out, but the tractor can still lock up. If you lose steering or the tractor begins to jackknife, ease off the brakes when safe until you have control again.

Answer

Hold full brake pressure so the trailer's ABS can take over

Answer

Turn the steering wheel sharply toward the trailer

Answer

Set the parking brakes

Question 2

Partway into a trip, the yellow ABS malfunction lamp on your instrument panel comes on and stays lit. What does the manual say it may mean?

Accepted Answer

ABS may have stopped working at one or more wheels — A lamp that stays on after the start-up bulb check, or lights once you are moving, signals that ABS may no longer be working at one or more wheels. Your normal brakes still work; drive normally and get the system serviced soon.

Answer

All braking has been lost and you must stop in the travel lane

Answer

The air tanks are nearly empty

Answer

The lamp is running its start-up bulb check

Question 3

In the manual Rhode Island tests from, a visible low air warning is required to switch on before tank pressure drops under what level?

Accepted Answer

60 psi — This edition of the manual sets the line at 60 psi (or half the governor cut-out pressure on older vehicles). It typically shows as a red light, and a buzzer may sound as well.

Answer

45 psi

Answer

100 psi

Answer

125 psi

Question 4

During a hard stop on a slick road, the ABS computer senses that a wheel is about to lock. What does it do?

Accepted Answer

Cuts braking pressure back to a safe level so you keep control — ABS watches for wheels that are about to lock. When it senses that, it lowers the braking pressure to a safe level, which helps you keep control instead of skidding.

Answer

Applies the spring brakes on that wheel

Answer

Raises pressure at the other wheels to stop you faster

Answer

Shuts off the air compressor to save air

Question 5

Using stab braking, you have released the brakes because the wheels locked. Why should you wait for the wheels to start rolling before braking fully again?

Accepted Answer

If you reapply before they roll, the vehicle will not straighten out — After you let off, it can take up to a second for locked wheels to roll again. Braking hard before that happens keeps the vehicle from straightening out.

Answer

Reapplying too soon trips the safety relief valve

Answer

The ABS lamp has to reset first

Answer

Waiting lets the spring brakes take over

Question 6

Partway down a long grade, your application pressure gauge shows you need more and more pressure just to keep the same speed. What does this mean, and what should you do?

Accepted Answer

Your brakes are fading, so you should slow down and get into a lower gear — Needing rising application pressure to hold a steady speed is the manual's sign that the brakes are fading. Its answer is to reduce speed and use a lower gear so the engine takes on more of the work of holding the vehicle back.

Answer

The air tanks are overfilled, so pump the pedal to bleed off pressure and hold your speed

Answer

The spring brakes are dragging, so push the parking brake knob in firmly and carry on

Answer

It is normal on a grade, so keep steady pressure on the pedal until you reach the bottom

Question 7

Your tractor has working ABS but your trailer has none. In an emergency stop, should you simply apply the brakes fully?

Accepted Answer

No, the manual's full-braking exception is only for vehicles with working ABS on all axles — The general rule is to use only as much braking as you need to stop safely and stay in control. The one exception, fully applying the brakes in an emergency, covers only straight trucks or combinations whose ABS works on every axle.

Answer

Yes, because tractor ABS makes full braking safe

Answer

Yes, as long as you are going under 40 mph

Answer

No, you should use only the parking brake

Question 8

On a dual air system, which tank's reading must still be at least 60 psi at the moment the low air warning comes on?

Accepted Answer

The tank with the lowest pressure — The warning has to come on before pressure falls under 60 psi, and on a dual system that is judged by whichever tank is lowest, so the warning appears before either system drops below 60 psi.

Answer

The tank with the highest pressure

Answer

Only the primary system's tank

Answer

Only the first tank the compressor fills

Question 9

You are using controlled braking in an emergency and realize you need to steer more than a little to avoid a hazard. What should you do with the brakes?

Accepted Answer

Release them, make the steering correction, then reapply as soon as you can — Controlled braking means braking as firmly as possible short of locking the wheels while keeping steering movements very small. If you need a bigger steering correction, or the wheels lock, let off the brakes and put them back on as soon as you can.

Answer

Press harder so the vehicle slows before you turn

Answer

Pull the parking brake knob to help slow down

Answer

Keep the same pressure and turn sharply

Question 10

A car suddenly pulls out in front of your truck, and your instinct is to hit the brakes. When does the manual call that a good response?

Accepted Answer

When there is enough room to stop and you brake correctly — Braking is the natural reaction, and it is a good one if you have the distance to stop and use the brakes properly, keeping the vehicle straight and able to turn if needed.

Answer

Always, since braking is the only safe choice

Answer

Only when the truck has ABS on every axle

Answer

Never, because you should always steer around instead

Question 11

Your truck has an automatic wig wag. Its arm dropped into view when pressure fell, and the compressor has now built pressure back above 60 psi. What happens to the arm?

Accepted Answer

It rises out of your view on its own — A wig wag lowers a mechanical arm into your line of sight when pressure falls below 60 psi. The automatic kind lifts itself back out of view once pressure climbs above 60 psi; only the manual reset kind has to be moved by hand.

Answer

It stays down until you push it back up by hand

Answer

It stays down until a mechanic resets it

Answer

It drops lower to warn that pressure is too high

Question 12

Only your tractor has ABS. As you brake, you see in the mirror that the trailer is starting to swing out. What does the manual tell you to do?

Accepted Answer

Ease off the brakes when it is safe — Tractor-only ABS helps you keep steering control and lowers the chance of a jackknife, but the trailer can still swing. Keep an eye on it, and ease off the brakes when it is safe if the trailer starts to swing out.

Answer

Brake harder so the tractor's ABS can straighten the trailer

Answer

Pull the parking brake knob

Answer

Switch to stab braking at full pressure

Rhode Island CDL — Air Brakes: Handling Emergencies practice test

Study questions with answers

1. Only your trailer has ABS. While braking, the tractor starts to jackknife and you are losing steering control. What should you do?

2. Partway into a trip, the yellow ABS malfunction lamp on your instrument panel comes on and stays lit. What does the manual say it may mean?

3. In the manual Rhode Island tests from, a visible low air warning is required to switch on before tank pressure drops under what level?

4. During a hard stop on a slick road, the ABS computer senses that a wheel is about to lock. What does it do?

5. Using stab braking, you have released the brakes because the wheels locked. Why should you wait for the wheels to start rolling before braking fully again?

6. Partway down a long grade, your application pressure gauge shows you need more and more pressure just to keep the same speed. What does this mean, and what should you do?

7. Your tractor has working ABS but your trailer has none. In an emergency stop, should you simply apply the brakes fully?

8. On a dual air system, which tank's reading must still be at least 60 psi at the moment the low air warning comes on?

9. You are using controlled braking in an emergency and realize you need to steer more than a little to avoid a hazard. What should you do with the brakes?

10. A car suddenly pulls out in front of your truck, and your instinct is to hit the brakes. When does the manual call that a good response?

11. Your truck has an automatic wig wag. Its arm dropped into view when pressure fell, and the compressor has now built pressure back above 60 psi. What happens to the arm?

12. Only your tractor has ABS. As you brake, you see in the mirror that the trailer is starting to swing out. What does the manual tell you to do?

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