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South Dakota CDL DMV Air Brakes 1

Take 6 practice tests for CDL is the best way to prepare for your South Dakota DMV exam is by taking our free practice tests. The following question are from real South Dakota 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. 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.

2. To make a stop in a vehicle using air brakes, the driver should:
Press down the brake pedal.
Lift the brake pedal toward them.
Push in the brake knob.
Pull out the brake knob.

To make a normal stop in an air-braked vehicle, push the brake pedal down and control the pressure so that the vehicle comes to a smooth, safe stop.

3. Braking mechanisms are located ____ a brake drum.
Outside
Inside
Next to
On top of

Drum brakes are attached to the wheels and located on the axles of a vehicle. The braking mechanisms that cause the vehicle to stop can be found inside of a drum brake.

4. Truck tractors with air brakes that were built on or after March 1, 1997 are equipped with:
An extra set of brakes.
Voice-activated brakes.
Cruise control.
Anti-Lock Braking Systems (ABS).

Truck tractors with air brakes that were manufactured on or after March 1, 1997 are required to be equipped with Anti-Lock Braking Systems (ABS). ABS is required in any other type of vehicle with air brakes that was manufactured on or after March 1, 1998.

5. Failing to drain air tanks could result in:
Water accumulations freezing and causing brake failure.
Squishy brakes.
Too much air collecting in the tanks.

In an air brake system, the air tanks must be periodically drained to remove accumulations of water and compressor oil. If water is not removed, it could freeze in cold weather and cause brake failure.

6. If the spring brakes are activated, you should never:
Push down the brake pedal.
Open the hood.
Release air from the air storage tanks.
Open the door to the cab.

Never apply the brake pedal if your spring breaks are activated. Brakes can be damaged if they are subject to both springs and air pressure.

7. Foundation brakes are used:
Only on the front wheels of a vehicle.
Only on the rear wheels of a vehicle.
On each wheel of a vehicle.

Foundation brakes are used on each wheel of a CMV. The most common type of foundation brake is the s-cam drum brake.

8. If your tractor is equipped with ABS but your trailer is not, the ABS:
Will not be effective.
Will still improve your steering control.
Will make jackknifing easier.
Will allow others to see when you brake.

In a tractor-trailer combination, if the tractor is equipped with an Anti-Lock Braking System (ABS) but the trailer is not, the ABS will still improve the driver's steering control. The driver should keep an eye on the trailer and let up on the brakes if the trailer begins to swing out.

9. If using air tanks with manually operated drains, how often should you drain the tanks?
Every day
Once a week
Once a month
Once every six months

In an air brake system with manually operated drains, the tanks should be drained at the end of each day of driving.

10. An air compressor governor controls:
When the air compressor pumps air into the air storage tanks.
How fast air is pumped into the air storage tanks.
The temperature of the air pumped into the air storage tanks.

In an air brake system, the air compressor governor controls when the air compressor pumps air into the air storage tanks.

11. Vehicles with dual air brake systems:
Have air pressure in the braking system even when the vehicle is not running.
Maintain some air pressure in the braking system when the vehicle is not running.
Must be run to build air pressure to allow the brakes to operate properly.
Maintain air pressure when shut off for periods of less than four hours.

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

12. 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.

13. If the spring brakes are on, you should:
Not use the brake pedal.
Press the accelerator.
Move the steering wheel.

Do not use the brake pedal when the spring brakes are on. This could damage the brakes by subjecting them to the combined forces of springs and air pressure.

14. When leaving your vehicle unattended:
The parking brake must be always be used.
The parking brake should never be used.
Windows in the cab should be lowered.

Always apply the parking brake when leaving your vehicle unattended.

15. When leaving a vehicle unattended, a driver should:
Always set the parking brake.
Only set the parking brake if the vehicle is parked on a slope.
Deflate the tires by 10 percent.

Always apply the parking brake when leaving your vehicle unattended.

16. 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.

17. Failing to drain the tanks in an air brake system can result in:
Water freezing and causing brake failure.
Squishy brakes.
Too much air collecting.
Too much fuel being carried.

In an air brake system, the air storage tanks must be drained to remove accumulated water and compressor oil. Failing to do this can cause damage. For example, water that has built up in the system could freeze in cold weather and cause brake failure.

18. On a truck with air brakes, the braking system’s air compressor:
Pumps air into the air storage tanks.
Fills the tires.
Moves air to the back of the truck.
Cleans the brakes.

In an air brake system, the air compressor pumps air into the air storage tanks. The air compressor is controlled by the air compressor governor.

19. Air tank drains should:
Not be used by the driver.
Only be used when it is wet outside.
Be used to drain the tanks completely.

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.

20. Why do large vehicles use air brakes?
Other brake systems squeak too loudly.
Air brakes are very effective systems.
Other braking systems are hard to come by.

If used and maintained properly, air brakes are a safe and effective way to stop large, heavy vehicles.

21. 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.

22. 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.

23. 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.

24. Air brakes use ____ to function.
Compressed air
Liquid air
Nitrogen

Air brakes function through the use of compressed air.

25. 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.

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