Alabama CDL — Air Brakes: Parking & Stopping Practice Test

Question 1

Bringing a truck with a manual gearbox to a routine stop, when should the clutch pedal go down?

Accepted Answer

Not until engine speed has dropped down near idle — Holding off until the revs fall close to idle keeps the stop smooth and keeps the engine from stalling; after you are stopped, pick a gear you can pull away in.

Answer

The moment your foot moves onto the brake pedal

Answer

Only once the vehicle has come to a complete halt

Answer

Partway through the stop, at roughly half of road speed

Question 2

In the service brake check you creep ahead at roughly five mph and press the pedal firmly. What are you looking for?

Accepted Answer

The truck tugging to one side, an odd feel, or a late stop — This slow-speed check exposes faults such as uneven braking, a strange pedal feel, or a stop that comes late, while you are still in the yard rather than out in traffic.

Answer

A drop in the engine oil pressure reading

Answer

Air escaping from the alcohol evaporator

Answer

The governor cutting the compressor out early

Question 3

On newer vehicles, how do you apply the parking (spring) brakes?

Accepted Answer

Pull out the yellow, diamond-shaped control knob — Newer air brake vehicles use a yellow, diamond-shaped push-pull knob; you pull the knob out to set the parking brakes and push it in to release them.

Answer

Push in a round green button

Answer

Hold the brake pedal down and shut off the engine

Answer

Turn a key beside the steering column

Question 4

How is the parking brake checked as part of the final air brake test?

Accepted Answer

Set it with the vehicle stopped and tug against it gently in a low gear — Setting the parking brake and then easing against it in a low gear shows whether it can really hold the vehicle before you take it out on the road.

Answer

Release it on a downgrade and count how far the vehicle rolls

Answer

Apply it at highway speed and time how long the stop takes

Answer

Watch the application gauge for one minute with the key off

Question 5

On a tractor or straight truck, spring brakes will come fully on when air pressure drops into roughly what range?

Accepted Answer

About 20 to 45 psi — When air pressure falls to about 20 to 45 psi (often between 20 and 30), the springs are no longer held back and the spring brakes apply fully.

Answer

About 80 to 100 psi

Answer

About 100 to 125 psi

Answer

About 125 to 150 psi

Question 6

With the engine off and a fully charged system, what is the maximum acceptable air loss rate for a single vehicle?

Accepted Answer

Less than 2 psi in one minute — During the leakage test on a fully charged system with the engine off, a single vehicle should lose less than 2 psi in one minute (combination vehicles are allowed less than 3 psi per minute).

Answer

Less than 10 psi in one minute

Answer

Up to 20 psi in one minute

Answer

Any amount as long as it stabilizes

Question 7

You will be stepping away from your truck for only a minute or two. What has to happen first?

Accepted Answer

Set the parking brakes, or chock the wheels, before you walk away — A truck left standing with nothing holding it can roll away and cause injury or damage, and the manual makes no exception for a short absence.

Answer

Nothing extra is needed for such a brief absence

Answer

Leaving the transmission in a low gear is enough by itself

Answer

Let the engine idle so the tanks stay charged

Question 8

Why should you avoid pressing the brake pedal while the spring brakes are already applied?

Accepted Answer

The combined forces can damage the brakes — Doing so combines the force of the springs with the air pressure, which can damage the brakes, so it is better never to press the pedal when the spring brakes are on.

Answer

It instantly drains all the air tanks

Answer

It disables the low air warning device

Answer

It permanently releases the parking brakes

Question 9

Why is it important to drain the air tanks completely?

Accepted Answer

To remove water and oil that could cause brake failure — Compressed air carries some water and compressor oil that settle at the bottom of the tank; the water can freeze in cold weather and cause the brakes to fail, so the tanks must be drained.

Answer

To let the compressor cool down between stops

Answer

To lower the pressure so the governor can reset

Answer

To add fresh alcohol to the braking system

Question 10

With a manually operated tank drain valve, how often must the driver drain the tanks?

Accepted Answer

At the end of each day of driving — A manual drain has to be opened by the driver, and it should be done at the end of each driving day to clear out the collected water and oil.

Answer

Only once a month

Answer

Only when the low air warning sounds

Answer

Every time the governor cuts out

Question 11

How are the powerful springs in spring brakes normally held back while you drive?

Accepted Answer

By air pressure holding them off — During driving, air pressure holds the strong springs back; if that air pressure is lost, the springs are released and put the brakes on.

Answer

By a locking pin the driver sets by hand

Answer

By hydraulic fluid in the chambers

Answer

By an electric solenoid at each wheel

Question 12

When is it best NOT to set the parking brakes?

Accepted Answer

When the brakes are very hot, or very wet in freezing weather — Avoid using the parking brakes when the brakes are very hot from coming down a steep grade or very wet in freezing temperatures; heat can damage them and wet brakes can freeze so the vehicle cannot move. Use wheel chocks instead.

Answer

Whenever the vehicle is parked on level ground

Answer

Any time the trailer is loaded

Answer

When the air tanks are fully charged

Alabama CDL — Air Brakes: Parking & Stopping practice test

Study questions with answers

1. Bringing a truck with a manual gearbox to a routine stop, when should the clutch pedal go down?

2. In the service brake check you creep ahead at roughly five mph and press the pedal firmly. What are you looking for?

3. On newer vehicles, how do you apply the parking (spring) brakes?

4. How is the parking brake checked as part of the final air brake test?

5. On a tractor or straight truck, spring brakes will come fully on when air pressure drops into roughly what range?

6. With the engine off and a fully charged system, what is the maximum acceptable air loss rate for a single vehicle?

7. You will be stepping away from your truck for only a minute or two. What has to happen first?

8. Why should you avoid pressing the brake pedal while the spring brakes are already applied?

9. Why is it important to drain the air tanks completely?

10. With a manually operated tank drain valve, how often must the driver drain the tanks?

11. How are the powerful springs in spring brakes normally held back while you drive?

12. When is it best NOT to set the parking brakes?

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