CDL - Air Brakes (Texas DPS)
Questions and Answers
- 1.
Which brake system is used "during normal driving"?
- A.
Emergency Brake
- B.
Service Brake
- C.
Parking Brake
Correct Answer
B. Service BrakeExplanation
The service brake is used during normal driving. This brake system is designed to slow down or stop the vehicle when needed during regular driving conditions. It is operated by the driver using the brake pedal, and it provides the necessary stopping power to safely control the vehicle's speed. The emergency brake, on the other hand, is used in emergency situations to stop the vehicle quickly, while the parking brake is used to keep the vehicle stationary when parked.Rate this question:
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- 2.
The air compressor is a device use to do what?
- A.
Send air to the s-cam brake in order to stop the vehicle.
- B.
Drain the air tank at the end of the day.
- C.
Pump air into the air storage tanks/reservoirs.
Correct Answer
C. Pump air into the air storage tanks/reservoirs.Explanation
The air compressor is a device that is used to pump air into the air storage tanks/reservoirs. This is important because the air stored in these tanks is used for various purposes in the vehicle, such as operating the brakes and other pneumatic systems. By pumping air into the tanks, the compressor ensures that there is a sufficient supply of compressed air available for the vehicle's operation.Rate this question:
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- 3.
The air compressor governor has a "cut-in" level of ________ and a "cut-out" level of _______?
- A.
60 psi ; 80 psi
- B.
20 psi ; 45 psi
- C.
100 psi ; 125 psi
Correct Answer
C. 100 psi ; 125 psiExplanation
The air compressor governor has a "cut-in" level of 100 psi and a "cut-out" level of 125 psi. This means that the air compressor will start running when the pressure in the system drops to 100 psi and will stop running once the pressure reaches 125 psi. This allows for efficient and controlled operation of the air compressor, ensuring that it only runs when necessary and maintains the desired pressure levels in the system.Rate this question:
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- 4.
Water can freeze in cold weather and cause brake failure.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
In cold weather, water can freeze and turn into ice. If this happens on the brakes of a vehicle, it can cause brake failure. When the brakes are frozen, they are unable to function properly, resulting in a loss of braking power. This can be extremely dangerous as it can lead to accidents and loss of control over the vehicle. Therefore, it is important to be aware of this risk and take necessary precautions in cold weather conditions.Rate this question:
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- 5.
Air storage tanks should be drained completely "at the end of each week of driving".
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Tanks should be drained on a daily basis.Rate this question:
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- 6.
An alcohol evaporator is a device used to do what?
- A.
Reduce the risk of ice in air brake valves and other parts during cold weather.
- B.
Provide the driver with a beverage when he/she is thirsty.
- C.
Instantly remove alcohol from the driver's blood-stream.
Correct Answer
A. Reduce the risk of ice in air brake valves and other parts during cold weather.Explanation
An alcohol evaporator is a device used to reduce the risk of ice in air brake valves and other parts during cold weather. This is important because ice formation in these components can lead to brake failure, compromising the safety of the vehicle and its occupants. By evaporating alcohol, the device helps to prevent the freezing of moisture and condensation in the air brake system, ensuring its proper functioning even in low temperatures.Rate this question:
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- 7.
At what psi should the "safety valve" open?
- A.
60 psi.
- B.
80 psi.
- C.
125 psi.
- D.
150 psi.
Correct Answer
D. 150 psi.Explanation
The "safety valve" should open at 150 psi. This means that when the pressure reaches or exceeds 150 psi, the safety valve will open to release the excess pressure and prevent any potential damage or accidents.Rate this question:
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- 8.
This type of brake uses air pressure to push the rod out, moving the slack adjuster, thus twisting the brake cam shaft. This turns the s-cam, which forces the brake shoes away from one another and presses them against the inside of the break drum.
- A.
Wedge Brakes
- B.
S-cam Brakes
- C.
Disc Brakes
Correct Answer
B. S-cam BrakesExplanation
S-cam brakes use air pressure to push the rod out, which moves the slack adjuster and twists the brake cam shaft. This twisting motion turns the s-cam, causing the brake shoes to move away from each other and press against the inside of the brake drum. This action creates friction, which slows down or stops the rotation of the wheel. S-cam brakes are commonly used in heavy-duty vehicles like trucks and buses.Rate this question:
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- 9.
Supply pressure gauges...
- A.
...tell you how much pressure you are applying to the brakes.
- B.
...tell you how well the air compressor is working.
- C.
...tell you how much pressure is in the air storage tanks.
Correct Answer
C. ...tell you how much pressure is in the air storage tanks.Explanation
Supply pressure gauges are used to measure the pressure in the air storage tanks. These gauges provide information about the amount of pressure that is currently present in the tanks. This is important because it allows the user to monitor and maintain the appropriate pressure levels for the system to function properly. By knowing the pressure in the air storage tanks, adjustments can be made to ensure that the system is operating safely and efficiently.Rate this question:
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- 10.
The application pressure gauge...
- A.
...tells you how much pressure you are applying to the brakes.
- B.
...tells you how much pressure is in the air storage tanks.
- C.
...tells you how well the air compressor is working.
Correct Answer
A. ...tells you how much pressure you are applying to the brakes.Explanation
The application pressure gauge tells you how much pressure you are applying to the brakes. This means that it provides information about the amount of force being exerted on the brake system when the brakes are applied. It is an important tool for monitoring and maintaining the proper braking pressure, ensuring safe and effective braking performance.Rate this question:
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- 11.
The low air pressure warning is only an audible signal.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
"A low air pressure warning signal is required on vehicles with air brakes. A warning signal you can see must come on before the air pressure in the tanks falls below a specified psi.Rate this question:
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- 12.
At what psi range will the "low air pressure warning signal" come on?
- A.
20-45 psi.
- B.
100-125 psi.
- C.
60-80 psi.
Correct Answer
C. 60-80 psi.Explanation
The "low air pressure warning signal" will come on when the air pressure in the system falls within the range of 60-80 psi. This indicates that the air pressure is below the recommended level and serves as a warning for the driver to take necessary action to address the low air pressure situation.Rate this question:
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- 13.
What is a "wig wag"?
- A.
A device used to signal for help in the event of an emergency.
- B.
A device used to signal the driver that he/she is running low on fuel.
- C.
A device used to warn the driver of low air pressure.
Correct Answer
C. A device used to warn the driver of low air pressure.Explanation
A "wig wag" is a device used to warn the driver of low air pressure. This device is typically found in vehicles equipped with air brakes, such as large trucks or buses. When the air pressure in the brake system drops below a certain level, the wig wag will activate and provide a visual or audible warning to the driver. This is important because low air pressure can lead to brake failure, making it crucial for the driver to be alerted and take appropriate action to prevent accidents.Rate this question:
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- 14.
The spring brakes will engage once the psi in the air storage tanks reaches 20-45 psi (typically 20-30 psi).
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
When the psi (pounds per square inch) in the air storage tanks reaches 20-45 psi, the spring brakes in a vehicle will engage. This is a safety feature that ensures the brakes are automatically applied when there is not enough air pressure to operate the regular braking system. Therefore, the statement is true.Rate this question:
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- 15.
When the low air pressure warning light and buzzer first come on, drive quickly to the next load/unload station to safely deliver any passengers aboard your vehicle.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
You should bring the vehicle to a safe stop right away, while you can still control the brakes.Rate this question:
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- 16.
If the brakes are out of proper adjustment, neither the regular brakes nor the emergency/parking brakes will work correctly.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
If the brakes are out of proper adjustment, it means that they are not set to the correct specifications. This can result in the brakes not functioning effectively, causing a decrease in stopping power. If the regular brakes are not adjusted properly, they may not be able to slow down or stop the vehicle efficiently. Similarly, if the emergency/parking brakes are not adjusted correctly, they may not be able to hold the vehicle in place or provide the necessary stopping power in emergency situations. Therefore, it is true that if the brakes are out of proper adjustment, neither the regular brakes nor the emergency/parking brakes will work correctly.Rate this question:
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- 17.
What is the purpose of the "dual parking control valve"?
- A.
To provide an additional air storage tank used for the purpose of getting the vehicle back to the service center.
- B.
To release the spring brakes so you can move the vehicle in the event of an emergency.
- C.
To provide the ability to open air powered doors in the event of an emergency.
Correct Answer
B. To release the spring brakes so you can move the vehicle in the event of an emergency.Explanation
The purpose of the "dual parking control valve" is to release the spring brakes so that the vehicle can be moved in the event of an emergency. This valve allows the driver to manually release the brakes, providing the ability to move the vehicle when necessary, such as in the case of a breakdown or emergency situation. It is an important safety feature that ensures the vehicle can be controlled and moved when needed.Rate this question:
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