Minnesota CDL — Air Brakes: Parking & Stopping Practice Test

Question 1

Your brakes have gotten soaked driving through deep water. What does the manual tell you to do about it?

Accepted Answer

Drive in a low gear while braking gently so the heat dries them — Soaked brakes are dried by rolling along in a low gear with light, steady pressure on the pedal, because the friction warms the linings and drives the moisture off.

Answer

Coast in neutral and let the airflow dry the drums

Answer

Set the parking brakes for several minutes so the springs squeeze the water out

Answer

Open every tank drain valve until only dry air remains in the system

Question 2

During a routine stop in a truck with a manual transmission, when should the clutch go in?

Accepted Answer

Not until engine rpm has fallen close to idle — Keep the clutch out while you squeeze the pedal for a smooth halt, and only depress it once engine speed has dropped to nearly idle. After the vehicle is standing still, pick the gear you will pull away in.

Answer

The instant your foot touches the brake pedal

Answer

At roughly half of the speed you started braking from

Answer

Only after the vehicle has been sitting still for a few seconds

Question 3

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

Accepted Answer

The combined force of the springs and air pressure could damage the brakes — Doing so adds air pressure on top of the spring force, and the combined forces could damage the brakes.

Answer

It could release air needed for the next stop

Answer

It resets the ABS malfunction lamp

Answer

It slowly drains the secondary tank

Question 4

How are the spring brakes kept released while you drive normally?

Accepted Answer

Air pressure holds the powerful springs back — While driving, air pressure holds the powerful springs back; if that air is lost, the springs push the brakes on.

Answer

The compressor mechanically locks them open

Answer

The modulating valve holds them out

Answer

The governor keeps them from engaging

Question 5

On newer air brake vehicles, what does the parking brake control usually look like?

Accepted Answer

A yellow, diamond-shaped push-pull knob — Newer vehicles use a yellow, diamond-shaped push-pull knob; you pull it out to set the parking (spring) brakes and push it in to release them.

Answer

A round green push button

Answer

A red lever mounted on the floor

Answer

A blue foot pedal beside the throttle

Question 6

How do you test that the parking brake will hold?

Accepted Answer

Set the parking brake and gently pull against it in a low gear — Stop the vehicle, set the parking brake, and gently pull against it in a low gear to confirm it holds.

Answer

Rev the engine to governor cutout and listen for leaks

Answer

Fan the pressure down until the spring brakes pop out

Answer

Push the brake pedal fully for one minute

Question 7

Traveling at 55 mph on dry pavement, roughly how many extra feet does air brake lag add before the vehicle starts slowing?

Accepted Answer

Around 32 feet — Compressed air needs a moment to reach the brake chambers, and at highway speed on dry pavement that pause eats up around 32 additional feet of roadway.

Answer

Around 8 feet

Answer

Around 90 feet

Answer

Around 150 feet

Question 8

What should you always do before leaving your vehicle unattended?

Accepted Answer

Set the parking brakes or chock the wheels — Never leave the vehicle unattended without setting the parking brakes or chocking the wheels, or it could roll away.

Answer

Drain the alcohol evaporator

Answer

Release the spring brakes

Answer

Pump the brake pedal several times

Question 9

Which way do you move the parking brake control knob to set and then release the parking brakes?

Accepted Answer

Pull it out to set them, then push it back in to release them — Setting the parking brakes means drawing the knob outward toward you; shoving that same knob back in lets air return to the chambers and releases them.

Answer

Push it in to set them, then pull it out to release them

Answer

Rotate it clockwise to set them and counterclockwise to release them

Answer

Hold it down until the low-air warning clears, then let it spring back

Question 10

When should you avoid setting the parking brakes and use wheel chocks instead?

Accepted Answer

When the brakes are very hot from coming down a steep grade — Don't set the parking brakes when they are very hot from just coming down a steep grade, because the heat can damage them; let them cool and use chocks.

Answer

Whenever you park on any downhill grade

Answer

Any time the vehicle is loaded

Answer

Whenever the tanks are fully charged

Question 11

Why shouldn't you set the parking brakes when the brakes are very wet in freezing temperatures?

Accepted Answer

The brakes could freeze so the vehicle cannot move — Very wet brakes set in freezing weather can freeze, leaving the vehicle unable to move; drive slowly in low gear first to warm and dry them.

Answer

The water raises tank pressure dangerously

Answer

The wig wag will not reset

Answer

The alcohol evaporator will overflow

Question 12

How often must you drain air tanks that have manually operated drain valves?

Accepted Answer

At the end of each day of driving — Tanks with manual drains have to be emptied by the driver at the end of each day of driving.

Answer

Only when the low-air warning comes on

Answer

Once a week

Answer

Only before a long downhill grade

Minnesota CDL — Air Brakes: Parking & Stopping practice test

Study questions with answers

1. Your brakes have gotten soaked driving through deep water. What does the manual tell you to do about it?

2. During a routine stop in a truck with a manual transmission, when should the clutch go in?

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

4. How are the spring brakes kept released while you drive normally?

5. On newer air brake vehicles, what does the parking brake control usually look like?

6. How do you test that the parking brake will hold?

7. Traveling at 55 mph on dry pavement, roughly how many extra feet does air brake lag add before the vehicle starts slowing?

8. What should you always do before leaving your vehicle unattended?

9. Which way do you move the parking brake control knob to set and then release the parking brakes?

10. When should you avoid setting the parking brakes and use wheel chocks instead?

11. Why shouldn't you set the parking brakes when the brakes are very wet in freezing temperatures?

12. How often must you drain air tanks that have manually operated drain valves?

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