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Wisconsin CDL DMV Air Brakes 1

Take 6 practice tests for CDL is the best way to prepare for your Wisconsin DMV exam is by taking our free practice tests. The following question are from real Wisconsin DMV practice test. More than 95% people pass a DMV exam when practice at DMV Practice Test.

Number of Test
6
Number of Question
25
Passing score
20
13%
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  • 0Incorrect
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Ouch! While you were on a roll there for a few questions, you didn’t pass this time. But I know this test, and I think you’ll pass next time. Really.

1. Applying the brake pedal causes air pressure to activate an electric switch and:
Turn off the brake lights.
Turn on the low pressure warning light.
Turn on the brake lights.
Turn off the low pressure warning light.

In a vehicle with air brakes, the brake lights are activated when the brake pedal is pushed and air pressure moves an electric switch. With the application of air pressure, the switch will then turn on the brake lights.

2. You should ____ if the low pressure warning signal activates while you are driving.
Stop where you are and park
Exit the roadway as soon as safely possible
Continue driving normally

If the low pressure warning signal activates while you are driving, it is important that you safely exit the roadway as soon as possible and park your vehicle. If the air pressure gets too low, the brakes will no longer work well enough for you to stop safely.

3. The air pressure in a dual air brake system should build from 85 to 100 psi within:
Two minutes.
15 seconds.
10 minutes.
45 seconds.

When inspecting a vehicle with a dual air brake system, you should wait for air pressure to build from 85 to 100 psi in both the primary and secondary systems. This should take about 45 seconds.

4. When traveling down a steep downgrade, the best way to use your brakes is to:
Ride the brakes all the way down the hill.
Apply the brakes for a few seconds, then release the brakes for a few seconds. Continue to repeat these steps as you travel down the hill.
Apply the brakes only near the bottom of the downgrade.
Apply consistent pressure to the brake pedal all the way down the hill.

On a long or steep downgrade, brakes should only be used to supplement the braking effect of the engine. Apply the brakes just enough to feel a definite slowing down, then release them once you are about 5 mph below your target "safe" speed. Once your vehicle reaches its safe speed again, repeat this process.

5. Brakes out of adjustment will:
Work properly.
Cause some of the brakes to overwork and malfunction.
Allow better acceleration.

Brakes out of adjustment will fade before those that are properly adjusted. Brake adjustment must be checked frequently to help prevent brake issues.

6. What kind of force do emergency brakes use?
Air pressure
Mechanical
Heavy

Air brakes are really three different braking systems: the service brake, the parking brake, and the emergency brake. Emergency and parking brakes are applied with mechanical force.

7. In a dual air brake system:
Each system has separate air tanks, hoses, and lines.
The systems share air tanks, but each has its own separate hoses and lines.
Each system uses the same lines and hoses.
One system is the main braking system and a second system is ready to be used if the first one fails.

A dual air brake system is made up of two separate air brake systems. The systems share a single set of brake controls, but each has its own air tanks, hoses, and lines.

8. Foundation brakes are used:
Only at the front wheels.
Only at the rear wheels.
Only at the driver’s side wheels.
At each wheel.

Foundation brakes are used at each wheel. The most common type is the S-cam drum brake.

9. When operating a vehicle with a dual air brake system, the driver should:
Let the vehicle warm up before driving to ensure that the fuel reaches the engine.
Let the air compressor build up a minimum of 100 psi pressure in the primary and secondary systems before driving.
Begin driving just after the vehicle starts.

Before driving a vehicle with a dual air brake system, allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems. Watch the air pressure gauges to monitor the pressure levels.

10. Air tank drains:
Allow rain water to enter the tanks.
Are used to drain water and oil from the tanks.
Should never be opened.
Must remain open while driving.

In an air brake system, the air storage tanks are equipped with drains to allow water and compressor oil to be removed. The water and oil can damage the brakes if left to accumulate in the system.

11. During an applied leakage test, what is the maximum leakage rate that is safe for a single vehicle with air brakes?
10 psi in one minute
5 psi in one minute
3 psi in one minute

It is important to know the maximum air loss rate that is safe for your specific vehicle. A single vehicle with air brakes should have a leakage rate no higher than 3 psi in a minute during an applied leakage test.

12. In a dual air brake system:
Air tanks are shared between both systems.
Each system has its own air tanks.
You must designate which system you are using.

There are two air brake systems in a dual air brake system. The systems share a set of brake controls, but each system has its own tanks, hoses, and lines.

13. Air tank drains:
Should not be used in cold weather.
Are helpful to remove water and oil from the air tanks.
Are used to move air to the brakes.

Compressed air in an air brake system usually has a certain amount of water and oil in it. This can harm the system if allowed to accumulate. Air tanks have drain valves to aid in removing water and oil from the compressed air.

14. What is brake lag?
The time required for the brakes to work after the brake pedal is pressed
The distance between the brake pedal and the floor
The amount of air pressure used to stop the vehicle

Because air takes time to flow through the air lines to the brakes, air brakes cannot begin working instantly. There is often a brake lag of at least one-half of a second between the moment the brake pedal is pressed and the moment the brakes begin to work.

15. How is the parking brake released?
By tapping the brake pedal three times
By pushing in the brake control knob
By starting the vehicle
By tapping the accelerator twice

In vehicles with air brakes, the parking brake is controlled by a knob. The knob is pulled out to apply the brakes, and pushed in to release them.

16. In a dual air brake system, if one air system is very low on pressure:
None of the brakes will work at all.
Either the front or rear brakes will not be fully operable.
There is usually no noticeable effect.

In a dual air brake system, either the front or rear brakes will not be fully operable if one of the air systems gets too low on pressure. If the air pressure in either tank gets too low while you are driving, you should exit the road and park as soon as possible.

17. What tells you how much pressure is in your vehicle's air tanks?
The supply pressure gauge
The ABS malfunction lamp
The tractor protection valve

A vehicle that is equipped with air brakes must also be equipped with a supply pressure gauge. This gauge tells the driver how much air pressure is in each of the vehicle's air tanks.

18. All air tanks must include:
A drain valve.
A lock.
A trap door.
A warning sticker.

Air brake system tanks must contain drain valves. These valves are used to drain accumulated oil and water from the tanks and may be either manually or automatically operated.

19. Service brakes should:
Be tested once a month.
Only be tested by a trained mechanic.
Be tested before every trip.

Before driving, you should always verify that your service brakes are in good working order. Testing the brakes before a trip allows you to locate any problems before you need to brake while on the road.

20. Air storage tanks:
Are not allowed on a vehicle.
Hold compressed air for the brakes.
Should be drained of excess air after every trip.

In an air brake system, the air storage tanks hold compressed air to be used by the brakes. The number and size of air tanks varies among vehicles.

21. What is removed when an air tank is drained?
Water and oil
Ammonia
Wood
Chlorine

In an air brake system, the air storage tanks are equipped with drains to allow water and compressor oil to be removed. The water and oil can damage the brakes if left to accumulate in the system.

22. What do the two systems of a dual air brake system share?
Hoses
An air compressor
Air tanks

Both systems in a dual air brake systems share a single air compressor. If the air compressor is damaged, neither system will be able to operate properly.

23. When the brake pedal is pushed down, air brakes work:
Immediately.
After a short delay.
After about a minute.
Only if it is warm outside.

Because air takes time to flow through the air lines to the brakes, air brakes cannot begin working instantly. There is often a brake lag of at least one-half of a second between the moment the brake pedal is pressed and the moment the brakes begin to work.

24. Most heavy-duty vehicles use ____ air brake systems.
Single
Dual
Triple
Quad

The majority of heavy-duty vehicles are equipped with dual air brake systems.

25. A tank endorsement is:
Only required when transporting gases.
Only required when transporting liquids.
Used when transporting both liquids and gases.
Optional when transporting hazardous materials.

In general, a tank endorsement is required to a drive tank vehicle used to transport liquids or gases. This applies to both hazardous and non-hazardous materials.

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