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Mississippi CDL DMV Air Brakes 1

Take 6 practice tests for CDL is the best way to prepare for your Mississippi DMV exam is by taking our free practice tests. The following question are from real Mississippi 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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1. The air entering air storage tanks may contain:
Water and compressor oil.
Frost.
Gravel.
Antifreeze.

The air that enters air storage tanks in an air brake system usually contains a certain amount of water and compressor oil. Because accumulations of these materials can damage the braking system, tanks are equipped with drains to allow their removal.

2. In cold weather, an alcohol evaporator should be checked and filled:
Once a week.
Every day.
Every hour.
Once a month.

An alcohol evaporator can help prevent ice from building up in an air brake system. In cold weather, the evaporator should be checked and refilled every day.

3. While driving, ____ generally holds spring brakes in place.
Air pressure
Electricity
Gasoline

While driving, spring brakes are generally held in place by air pressure. If the air pressure gets low enough, the springs will activate the brakes.

4. 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.

5. During an applied leakage test, the maximum leakage rate for a single vehicle with air brakes is:
3 psi in one minute.
6 psi in one minute.
8 psi in one minute.
4 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.

6. 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.
Clean the air in the passenger compartment.

In an air brake system, air tanks have drains to remove accumulations of water and compressor oil. Allowing water and oil to accumulate in the system could cause damage to the brakes. Manually operated drains should be used daily.

7. A low air pressure warning signal:
Is not recommended on vehicles with air brakes.
Is required on vehicles with air brakes.
Is optional on vehicles with air brakes.

Any vehicle with air brakes must be equipped with a low air pressure warning signal.

8. When the brake pedal is depressed, air brakes work:
Immediately.
After a short delay.
After about a minute.
Only if the green lever on the control panel is pushed down.

After the brake pedal is pushed down in a vehicle with air brakes, it takes a half-second or more for air to flow through the lines and make the brakes work. This contrasts with hydraulic brakes used in cars and light and medium trucks, which instantly begin working when the pedal is pushed.

9. If you’re driving and the ABS warning light comes on, it means:
The ABS is working properly.
The ABS has just been activated.
The ABS is not working properly.
The ABS needs to be activated.

Vehicles with Anti-Lock Braking Systems (ABS) have yellow malfunction lights to alert the driver if something is wrong with the braking system. If these lights activate, the driver may have lost ABS on one or more wheels.

10. Truck tractors with air brakes built on or after March 1, 1997 must have:
An Anti-Lock Braking System (ABS).
Bluetooth.
A GPS.

Truck tractors with air brakes built on or after March 1, 1997, and other vehicles with air brakes built on or after March 1, 1998, must be equipped with anti-lock brakes.

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

Compressed air in an air brake system usually contains a certain amount of water and compressor oil. The water and oil can damage the brakes if left to accumulate in the system. Manually operated air tank drains must be opened daily to remove this build-up.

12. A one-way check valve:
Drains the water and compressor oil from the air tanks.
Prevents air from escaping if the air compressor has a leak.
Activates the emergency brakes when there is a leak.
Holds the spring brakes in position until they are used.

A one-way check valve is required to be between an air compressor and the first main reservoir. This valve prevents air from escaping the system if the air compressor develops a leak.

13. On trucks and buses, where are ABS malfunction lamps located?
On the driver’s door
On the instrument panel
On the outside of the vehicle by the passenger’s door
Under the hood

Tractors, trucks, and buses with Anti-Lock Braking Systems (ABS) have yellow malfunction lamps located on their instrument panels. Trailers have yellow ABS malfunction lamps on their left side, either on the front or rear corner.

14. Truck tractors with air brakes built on or after March 1, 1997 must have:
An Anti-Lock Braking System (ABS).
Bluetooth.
GPS.
A rear back-up camera.

Truck tractors with air brakes built on or after March 1, 1997 must be equipped with Anti-Lock Braking Systems (ABS).

15. Front brake limiting valves were intended to:
Prevent the front tires from skidding.
Prevent the front tires from overheating.
Create equal brake usage.
Remove uncertainty when applying the brakes.

Some older vehicles with air brakes have front brake limiting valves. These valves were intended to reduce the risk of front wheels skidding. However, research has shown that such devices are unnecessary, so they should be left in the "normal" position.

16. Front wheel braking works:
Only on packed snow.
Under all conditions.
Only if the road is dry.
Under most conditions.

Front wheel braking is effective under all road conditions. It is unlikely that you will experience a front wheel skid, even on ice.

17. When you need to stop in an emergency, you should:
Lock the wheels and skid to a stop.
Stop in a way that keeps your vehicle in a straight line.
Stop in a way that turns your vehicle.
Expect your vehicle to slow down more quickly than usual.

If you need to make an emergency stop, you can use either the controlled braking method or the stab braking method. It's important to brake in a way that keeps your vehicle traveling in a straight line while still allowing you to turn, if necessary.

18. Both systems in a dual air brake systems share:
Air tanks.
Hoses.
Air lines.
An air compressor.

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

19. An Anti-Lock Braking System (ABS):
Is not available for vehicles with air brakes.
Is not helpful in most driving situations.
Can help you maintain control when braking.

Anti-Lock Braking Systems (ABS) are compatible with air brakes and help a driver maintain control of their vehicle by preventing wheel lockup.

20. During a static leakage test, the maximum leakage rate for a single vehicle with air brakes is ____ in one minute.
1 psi
2 psi
3 psi
4 psi

When performing a static leakage test on a single vehicle with air brakes, the leakage rate should be no more than 2 psi in a minute. If air leaks from the air brake system at a quicker rate, the vehicle should not be driven because something likely needs to be repaired.

21. A driver can rely on front wheel braking to work:
On dry roadways only.
Under all conditions.
Under all conditions, except for snow.

Front wheel braking is effective under all road conditions. It is unlikely that you will experience a front wheel skid, even on ice.

22. What kind of brakes do most newer heavy-duty trucks use?
Single air brakes
Dual air brakes
Triple air brakes

Most newer heavy-duty vehicles use dual air brake systems. A dual air brake system has two separate air brake systems which use a single set of brake controls.

23. How many air storage tanks are used in an air brake system?
Two tanks
Four tanks
Six tanks
The number varies.

Air storage tanks are used to hold compressed air. The number and size of air tanks in an air brake system varies among vehicles.

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

In an air brake system, the air tanks are equipped with drains that allow water and compressor oil to be removed from the system. If allowed to build up, water and compressor oil can damage an air brake system.

25. The application pressure gauge:
Shows how much air pressure is being applied to the brakes.
Shows the temperature of air being used in the braking system.
Shows the pressure of the air coming from the compressor.
Shows the number of times the brakes have been used.

In an air brake system, the application pressure gauge shows how much air pressure is being applied to the brakes. Not all vehicles with an air brake system have this gauge.

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