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New Mexico CDL DMV Air Brakes 2

Take 6 practice tests for CDL is the best way to prepare for your New Mexico DMV exam is by taking our free practice tests. The following question are from real New Mexico 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. You should test the low pressure warning signal by:
Turning on the engine and applying the trailer hand brake.
Rapidly pressing and releasing the brake pedal.
Removing wheel chocks and disengaging the parking brake.

It is essential that your low pressure warning light functions properly. After allowing the system to charge, you can test the warning signal by rapidly applying and releasing the brake pedal. This will release air from the braking system and the warning signal should come on when pressure drops to a dangerous level.

2. In a vehicle with dual air brakes, a leak in one system ____ the second system.
Will always affect
May not affect
Is caused by

A dual air brake system is made up of two separate air brake systems. If there is an air leak in one system, it may not affect the other.

3. Some water and compressor oil is usually found in the compressed air within an air brake system. The water and compressor oil:
Are necessary for the proper function of the system.
Should take up about 10 percent of the tank.
Should be removed regularly.

If water and compressor oil are left to build up in an air brake system, the system can be damaged. Air storage tanks are equipped with drains to allow this accumulation to be removed. Manually controlled drains should be operated at the end of each day of driving.

4. The ____ between an air compressor and reservoir tank prevents air from escaping if the air compressor has a leak.
Slack adjuster
One-way check valve
Tractor protection valve

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.

5. An emergency brake must be controlled by:
Mechanical force.
Air pressure.
Gravity.

All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. Because air pressure can eventually leak away, emergency and parking brakes should be held on by mechanical force.

6. 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.

7. 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.

8. Braking mechanisms are located inside:
The fifth wheel.
A brake drum.
The landing gear.

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.

9. Air pressure should build up in a single air system within:
15 minutes.
12 minutes.
Three minutes.

In single air systems, air pressure should build from approximately 50 to 90 psi within three minutes.

10. During an applied leakage test, the maximum leakage rate for a triple combination vehicle is ____ in a minute.
2 psi
4 psi
6 psi

It is important to know the maximum air loss rate that is safe for your specific vehicle. A triple combination should have a leakage rate no higher than 6 psi in a minute during an applied leakage test.

11. What does the air compressor governor do?
It stops the compressor from pumping air.
It turns on the air compressor.
It stores the compressed air.

In an air brake system, the air compressor governor controls when the air compressor pumps air into the storage tanks. It stops pumping if the pressure in the tanks becomes too high, and begins pumping if the pressure becomes too low.

12. Before driving a vehicle with air brakes, you should ensure that the ____ come on automatically when air pressure falls below 45 psi.
Spring brakes
Parking brakes
Air brakes

Before driving a vehicle with air brakes, you should ensure that the spring brakes come on automatically when air tank pressure falls to a level between 20 and 45 psi. You can do this by chocking the wheels and releasing air from the braking system by stepping on and off the brake pedal. Once the pressure levels drop to an unsafe level, the parking brake valve should pop out and spring brakes should come on.

13. 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.

14. Anti-Lock Braking Systems (ABS):
Reduce a vehicle's normal braking capacity.
Are in addition to other braking systems and do not reduce a vehicle's braking power.
Are not effective on larger vehicles.

If equipped, ABS is in addition to a vehicle's normal braking system and does not increase or decrease the braking power of any other system. ABS only activates when a vehicle's wheels are about to lock.

15. 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.

16. A dual air brake system:
Consists of two separate air brake systems that share a single set of controls.
Is a single air brake system with two different sets of controls.
Consists of one air brake system for the left side of the truck and one system for the right side of the truck, each with its own set of controls.

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. One system typically operates the regular brakes on the rear axle or axles while the other system operates the regular brakes on the front axle.

17. If the safety relief valve in the air brake system releases air:
The compressor needs more air.
The air pressure has become too high.
The brakes are fully operational.

An air brake system has a safety relief valve, which releases air from the tanks if the pressure gets too high. If the valve must operate, something in the system is wrong and should be addressed by a mechanic.

18. What color light indicates a vehicle's ABS is not working?
Green
Blue
Yellow

On vehicles with Anti-Lock Braking Systems (ABS), yellow malfunction lamps alert the driver to ABS malfunction.

19. Air brakes use ____ to function.
Compressed air
Liquid nitrogen
Carbon dioxide

The brakes in an air brake system use compressed air to function properly.

20. An alcohol evaporator is especially important:
In cold weather.
In hot weather.
In dry weather.

Some air brake systems contain an alcohol evaporator. This evaporator introduces alcohol into the system to help prevent ice from forming in cold weather.

21. When an S-cam turns inside a brake drum, the S-cam:
Presses the brake shoes against the inside of the brake drum.
Presses the brake shoes against the brake linings.
Presses the brake linings against the wheel axles.

When a brake pedal is pressed and the S-cam is turned, the S-cam presses the brake shoes against the inside of the brake drum. This causes friction and will cause the vehicle to slow.

22. 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.

23. If the safety relief valve in the air brake system releases air:
The compressor needs more air.
There is something wrong with the brakes.
You may continue driving.

An air brake system has a safety relief valve, which releases air from the tanks if the pressure gets too high. If the valve must operate, something in the system is wrong and should be addressed by a mechanic.

24. Air tank drains should:
Only be used by mechanics.
Only be used when it is wet outside.
Be used to drain the tanks completely.

In an air brake system, air tank drains are used to remove water and compressor oil from the air tanks. When operating a drain, be sure to drain the tank completely.

25. If you are braking on dry pavement while traveling at 55 mph, how much distance will brake lag add to your overall stopping distance?
32 feet
45 feet
20 feet

The total stopping distance for vehicles equipped with air brakes is made up of four factors: perception distance, reaction distance, brake lag distance, and braking distance. When braking at a speed of 55 mph while driving on dry pavement, the brake lag can add around 32 feet to the vehicle's total stopping distance.

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