CDL Air Brakes Endorsement II Practice
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What is a dual air brake system?
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A two brake system, one operates the front brakes and one operates the back brakes.
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A two braking system, one for each side of the vehicle.
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A two braking system, one for daytime and one for nighttime driving.
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This practice quiz is designed for individuals seeking the CDL Air Brakes Endorsement. It covers key aspects of air brake systems in commercial vehicles, including dual systems, slack adjusters, and safety protocols, enhancing both knowledge and compliance with transportation regulations.
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- 2.
What are the slack adjusters?
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It is the space between the back wheels.
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It is an adjusting nut on the backside of the brake drum used for adjusting the brakes.
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It is an adjusting nut under the cab to adjust the springs.
Correct Answer
A. It is an adjusting nut on the backside of the brake drum used for adjusting the brakes.Explanation
The slack adjusters are not the space between the back wheels or an adjusting nut under the cab to adjust the springs. The correct answer is that slack adjusters are an adjusting nut on the backside of the brake drum used for adjusting the brakes. This nut is responsible for maintaining the proper tension on the brake shoes, ensuring that they make proper contact with the drum to effectively stop the vehicle.Rate this question:
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- 3.
How can you check the slack adjuster?
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Park on level ground, turn off parking brakes, pull hard on each slack adjuster. It shouldn't move more than one inch.
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Park on level ground, turn off parking brake and press brake pedal.
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Park on an incline and see if the vehicle rolls.
Correct Answer
A. Park on level ground, turn off parking brakes, pull hard on each slack adjuster. It shouldn't move more than one inch.Explanation
To check the slack adjuster, it is necessary to park the vehicle on level ground and turn off the parking brakes. Then, one needs to pull hard on each slack adjuster. If the slack adjuster moves more than one inch, it indicates that it is not properly adjusted and requires attention.Rate this question:
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- 4.
How can you test the low pressure warning signal?
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While the engine is running, step on and off the brake pedal.
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Shut off the engine and see if the air pressure leaks down.
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Shut off the engine with enough air pressure, turn on the electrical power and step on and off the brake pedal until the low air pressure warning signal comes on.
Correct Answer
A. Shut off the engine with enough air pressure, turn on the electrical power and step on and off the brake pedal until the low air pressure warning signal comes on. -
- 5.
What can you check to see if the spring brakes come on automatically?
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Step on and off the brake, with the engine off, the parking brake knob should pop out when air pressure falls between 20-40 psi.
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Get under the vehicle and pull on the spring brakes.
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Turn on the engine and pump the brake pedal down to the floor.
Correct Answer
A. Step on and off the brake, with the engine off, the parking brake knob should pop out when air pressure falls between 20-40 psi.Explanation
To check if the spring brakes come on automatically, you should step on and off the brake with the engine off. If the parking brake knob pops out when the air pressure falls between 20-40 psi, it indicates that the spring brakes are functioning correctly.Rate this question:
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- 6.
What are the maximum leakage rates?
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Less than four psi in one minute for single vehicles and less than eight psi in one minute for combination vehicles.
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Less than two psi in one minute for single vehicles and less than three psi in one minute for combination vehicles.
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Less than six psi for all vehicles.
Correct Answer
A. Less than two psi in one minute for single vehicles and less than three psi in one minute for combination vehicles.Explanation
The maximum leakage rates are less than two psi in one minute for single vehicles and less than three psi in one minute for combination vehicles. This means that the air pressure in the tires should not decrease by more than two psi in one minute for single vehicles and three psi in one minute for combination vehicles. Any leakage rate exceeding these limits would be considered excessive and could indicate a problem with the vehicle's tires or air system.Rate this question:
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- 7.
Should you ever leave your vehicle unattended without applying parking brakes or chocking the wheels?
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Yes
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No
Correct Answer
A. NoExplanation
Leaving a vehicle unattended without applying parking brakes or chocking the wheels is not recommended. This is because it can lead to the vehicle rolling away, causing accidents or damage. Applying parking brakes or chocking the wheels helps to ensure that the vehicle remains stationary and does not pose a risk to others or property. Therefore, the correct answer is "No."Rate this question:
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- 8.
If you are away from your vehicle only a short time, you don't need to use the parking brake.
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True
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False
Correct Answer
A. FalseExplanation
The statement is false because even if you are away from your vehicle for a short time, it is still necessary to use the parking brake. The parking brake is designed to hold the vehicle in place and prevent it from rolling, especially on inclines or uneven surfaces. Failing to engage the parking brake can result in the vehicle moving unexpectedly, causing damage or injury. Therefore, it is important to always use the parking brake whenever leaving a vehicle unattended, regardless of the duration.Rate this question:
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- 9.
How often should you drain air tanks?
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Daily
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Weekly
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Monthly
Correct Answer
A. DailyExplanation
Air tanks should be drained daily to remove any accumulated moisture or condensation. This is important because moisture can cause corrosion and damage to the tank, as well as affect the performance of compressed air systems. Regularly draining the air tanks helps to maintain the quality and efficiency of the compressed air system.Rate this question:
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- 10.
The use of brakes on a long steep downgrade is only a supplement to the braking effect of the engine.
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True
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False
Correct Answer
A. TrueExplanation
When driving on a long steep downgrade, the engine alone may not provide enough braking power to slow down or stop the vehicle. Therefore, the use of brakes becomes necessary to supplement the engine's braking effect. This means that the statement "The use of brakes on a long steep downgrade is only a supplement to the braking effect of the engine" is true.Rate this question:
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- 11.
What factors can cause brakes to fade or fail?
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Not pressing the brake pedal hard enough.
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Over heating, low air pressure, and not relying on the engine braking effect.
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Not taking your foot off the accelerator pedal.
Correct Answer
A. Over heating, low air pressure, and not relying on the engine braking effect.Explanation
Brakes can fade or fail due to overheating, which can occur when the brakes are used excessively or for prolonged periods. Low air pressure can also cause brake failure as it affects the proper functioning of the braking system. Additionally, not relying on the engine braking effect, which helps to slow down the vehicle by downshifting gears, can put excessive strain on the brakes and lead to their failure.Rate this question:
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- 12.
Why should you be in the proper gear before starting down a hill?
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So you only have to apply the brake just hard enough to feel a definite slowdown
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So you don't have to shift gears going downhill.
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So you can go through the gears on the way down.
Correct Answer
A. So you only have to apply the brake just hard enough to feel a definite slowdownExplanation
Being in the proper gear before starting down a hill allows you to control your speed more effectively. By being in the correct gear, you can take advantage of engine braking, which helps to slow down the vehicle without relying solely on the brakes. This means that you only need to apply the brake lightly to feel a definite slowdown, reducing the risk of overheating the brakes or losing control of the vehicle. Shifting gears while going downhill can be risky and may cause a loss of control, so it is best to be in the proper gear before starting the descent.Rate this question:
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- 13.
If oil and water collect in the air tanks what can happen to the brakes?
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The brakes could heat up.
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The brakes could fail.
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The brakes could lock up.
Correct Answer
A. The brakes could fail.Explanation
If oil and water collect in the air tanks, it can cause the brakes to fail. Oil and water can contaminate the brake system, leading to a loss of brake pressure and reduced braking effectiveness. This can result in the brakes not being able to generate enough force to stop the vehicle, increasing the risk of accidents and loss of control. Therefore, it is important to regularly maintain and drain the air tanks to prevent the accumulation of oil and water.Rate this question:
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- 14.
What is the purpose of an alcohol evaporator?
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So you don't have to drain the air tanks as often.
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To have a drink available if you get thirsty.
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To reduce the risk of ice in the brake valves and other parts in cold weather.
Correct Answer
A. To reduce the risk of ice in the brake valves and other parts in cold weather.Explanation
The purpose of an alcohol evaporator is to reduce the risk of ice in the brake valves and other parts in cold weather. This device helps prevent the formation of ice by evaporating alcohol into the air system, which lowers the freezing point of any moisture present. By reducing the risk of ice formation, the evaporator helps maintain the proper functioning of the brake valves and other components, ensuring the safety and efficiency of the braking system in cold weather conditions.Rate this question:
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- 15.
What is another name for controlled braking?
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Steady braking
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Squeeze braking
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Hard braking
Correct Answer
A. Squeeze brakingExplanation
Squeeze braking is another name for controlled braking. This term refers to the technique of gradually applying pressure to the brakes in a smooth and controlled manner, rather than abruptly slamming them on. This allows for better control of the vehicle and reduces the risk of skidding or losing control.Rate this question:
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Current Version
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Mar 21, 2023Quiz Edited by
ProProfs Editorial Team -
Aug 21, 2012Quiz Created by
Jakexal
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