Knowledge Of Air Brakes
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Questions and Answers
- 1.
When you apply the brakes, the brake shoes/linings are pressed against the
- A.
S-cam
- B.
Slack adjuster
- C.
Brake drum
- D.
All of the above
Correct Answer
C. Brake drumExplanation
When you apply the brakes, the brake shoes/linings are pressed against the brake drum. This is because the brake drum is a rotating component attached to the wheel, and when the brakes are engaged, the brake shoes or linings are pushed against the inner surface of the drum, creating friction and causing the wheel to slow down or stop. The S-cam and slack adjuster are components of the braking system that help to control the movement and positioning of the brake shoes, but they do not directly come into contact with the drum. Therefore, the correct answer is the brake drum.Rate this question:
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- 2.
With air brake vehicles, the parking brakes should be used
- A.
As little as possible
- B.
Whenever you leave the vehicle unattended
- C.
Only during pre-trip inspections
- D.
None of the above
Correct Answer
B. Whenever you leave the vehicle unattendedExplanation
Whenever you leave the vehicle unattended, the parking brakes should be used. This is important to ensure that the vehicle remains stationary and does not roll away. The parking brakes provide an additional level of safety, especially for air brake vehicles, which may require more time to build up air pressure before the brakes can be fully engaged. Using the parking brakes whenever the vehicle is unattended helps prevent accidents and ensures the vehicle remains in place.Rate this question:
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- 3.
All air brake equipped vehicles have
- A.
An air use gauge
- B.
A backup hydraulic system
- C.
An air supply pressure gauge
- D.
All of the above
Correct Answer
C. An air supply pressure gaugeExplanation
An air supply pressure gauge is a crucial component in air brake equipped vehicles as it allows the driver to monitor the pressure of the air supply in the braking system. This gauge helps ensure that the air pressure is within the appropriate range for optimal braking performance. By constantly monitoring the air supply pressure, the driver can detect any abnormalities or leaks in the system, allowing for timely maintenance and repairs. Therefore, it is essential for all air brake equipped vehicles to have an air supply pressure gauge.Rate this question:
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- 4.
The parking or emergency brake on a heavy vehicle can only be held in position by something that cannot leak away, like
- A.
Spring pressure
- B.
Air pressure
- C.
Hydraulic pressure
- D.
All of the above
Correct Answer
A. Spring pressureExplanation
The parking or emergency brake on a heavy vehicle can only be held in position by something that cannot leak away. Spring pressure is a reliable and effective method to hold the brake in position because springs do not rely on external factors like air pressure or hydraulic pressure, which can potentially leak or fail. Springs provide a constant force to keep the brake engaged, ensuring the vehicle remains stationary and safe.Rate this question:
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- 5.
The parking or emergency brakes of trucks and buses can be legally held on by _____ pressure
- A.
Air
- B.
Spring
- C.
Fluid
- D.
None of the above
Correct Answer
B. SpringExplanation
The correct answer is "spring". In trucks and buses, the parking or emergency brakes can be legally held on by spring pressure. This means that the brakes are engaged and held in place by the force exerted by a spring, rather than by air pressure or fluid pressure.Rate this question:
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- 6.
Modern air brake systems are three different systems combined together. They are the service, parking and the _______ brakes
- A.
S-cam
- B.
Foot
- C.
Emergency
- D.
All of the above
Correct Answer
C. EmergencyExplanation
The modern air brake system consists of three different systems: the service brake, the parking brake, and the emergency brake. The emergency brake is a crucial component of the system as it provides an additional braking mechanism in case of emergencies or sudden stops. It allows the driver to quickly apply maximum braking force to bring the vehicle to a halt in critical situations. Therefore, the correct answer is "emergency."Rate this question:
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- 7.
The stop light switch
- A.
Tells you when the air brake system is low on air pressure
- B.
Turns on the brake lights to warn drivers behind you
- C.
Tells you when you need to use your emergency brakes
- D.
All of the above
Correct Answer
B. Turns on the brake lights to warn drivers behind youExplanation
The correct answer is "turns on the brake lights to warn drivers behind you." The stop light switch is responsible for activating the brake lights when the driver applies the brakes. This alerts drivers behind the vehicle to slow down or stop, ensuring their safety and preventing accidents.Rate this question:
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- 8.
If your truck has a dual air brake system and one of the systems is low on pressure
- A.
The manual slack adjusters on the S-cam brakes are not set properly
- B.
Either the front or rear brakes will not be fully operational
- C.
The brake drums will not be fully pressurized
- D.
All of the above
Correct Answer
B. Either the front or rear brakes will not be fully operationalExplanation
If the truck has a dual air brake system and one of the systems is low on pressure, it means that there is insufficient pressure to fully engage the brakes on either the front or rear wheels. As a result, either the front or rear brakes will not be fully operational, leading to decreased braking efficiency and potentially compromising the safety of the vehicle.Rate this question:
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- 9.
The braking power of the spring brakes
- A.
Is not affected by the condition of the service brakes
- B.
Can only be tested by highly trained brake service people
- C.
Depends on the service brakes being in adjustment
- D.
All of the above
Correct Answer
C. Depends on the service brakes being in adjustmentExplanation
The braking power of the spring brakes depends on the service brakes being in adjustment. This means that if the service brakes are not properly adjusted, it can affect the braking power of the spring brakes. Therefore, it is important to ensure that the service brakes are in proper working condition and adjusted correctly in order to maintain the effectiveness of the spring brakes.Rate this question:
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- 10.
The application pressure gauge shows how much air pressure you
- A.
Are applying to the brakes
- B.
Have in the air tanks
- C.
Have in the modulating control valve
- D.
All of the above
Correct Answer
A. Are applying to the brakesExplanation
The application pressure gauge shows how much air pressure you are applying to the brakes. This gauge is used to monitor the amount of pressure being exerted on the brake system, allowing the driver to ensure that the brakes are being applied with the appropriate force. By observing the application pressure gauge, the driver can adjust their braking technique to ensure optimal braking performance and safety.Rate this question:
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- 11.
Before driving a truck or bus with a dual air brake system, the pressure in each system should be at least ________ psi
- A.
80
- B.
100
- C.
120
- D.
All of the above
Correct Answer
B. 100Explanation
Before driving a truck or bus with a dual air brake system, the pressure in each system should be at least 100 psi. This ensures that there is enough pressure to effectively engage the air brakes and provide sufficient stopping power for the vehicle. Having the correct pressure in each system is crucial for safe operation and compliance with regulations.Rate this question:
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- 12.
If your truck or bus has dual parking control valves, you can use pressure from a separate tank to
- A.
Release the spring emergency/parking brakes to move a short distance
- B.
Balance the service brake system when you are parking
- C.
Stay parked twice as long without using up service air pressure
- D.
All of the above
Correct Answer
A. Release the spring emergency/parking brakes to move a short distanceExplanation
If your truck or bus has dual parking control valves, you can use pressure from a separate tank to release the spring emergency/parking brakes to move a short distance. This means that instead of relying on the service air pressure to release the brakes, you can use the pressure from a separate tank. This can be useful when you need to move the vehicle a short distance without using up the service air pressure.Rate this question:
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- 13.
The brake pedal in an air brake system
- A.
Connects the slack adjusters by a series of rods and linkages
- B.
Controls the speed of the air compressor
- C.
Controls the air pressure applied to put on the brakes
- D.
All of the above
Correct Answer
C. Controls the air pressure applied to put on the brakesExplanation
The brake pedal in an air brake system controls the air pressure applied to put on the brakes. This means that when the driver presses the brake pedal, it activates the air pressure system, which then applies the necessary pressure to engage the brakes and slow down or stop the vehicle. By controlling the air pressure, the brake pedal allows for precise control over the braking action, ensuring the vehicle can be brought to a safe stop.Rate this question:
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- 14.
What is the first thing you should do when a low air pressure warning comes on
- A.
Adjust the brake pedal for more travel
- B.
Stop and safely park as soon as possible
- C.
Open the air supply control valve
- D.
All of the above
Correct Answer
B. Stop and safely park as soon as possibleExplanation
When a low air pressure warning comes on, the first thing you should do is stop and safely park as soon as possible. This is because low air pressure can greatly affect the braking system of a vehicle, making it unsafe to continue driving. Adjusting the brake pedal for more travel or opening the air supply control valve may not address the underlying issue causing the low air pressure warning, and it is crucial to prioritize safety by stopping and parking the vehicle to prevent any potential accidents or further damage.Rate this question:
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- 15.
The S-cam
- A.
Forces the brake shoes against the inside of the brake drum
- B.
Controls the flow of air into each of the brake chambers
- C.
Pulls the brake shoes away from the drum and allows the wheels to roll freely
- D.
All of the above
Correct Answer
C. Pulls the brake shoes away from the drum and allows the wheels to roll freelyExplanation
The S-cam pulls the brake shoes away from the drum and allows the wheels to roll freely. This is because when the brake pedal is released, the S-cam rotates and pushes the brake shoes away from the drum, releasing the pressure and allowing the wheels to rotate without any friction. This action is essential for the smooth operation of the brakes and enables the vehicle to move freely.Rate this question:
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- 16.
When is it ok to leave your truck unattended without applying the parking brake or chocking the wheels?
- A.
If you will only be away from the truck for a few minutes
- B.
If you are conducting a pre-trip inspection
- C.
Never
- D.
None of the above
Correct Answer
C. NeverExplanation
It is never okay to leave your truck unattended without applying the parking brake or chocking the wheels. This is because doing so can result in the truck rolling away, causing accidents or damage to property. It is important to always ensure that the truck is secure before leaving it unattended to prevent any potential hazards.Rate this question:
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- 17.
In air brake vehicles, the parking brakes should be used
- A.
Any time the vehicle is parked
- B.
To hold your speed when going downhill
- C.
As little as possible
- D.
All of the above
Correct Answer
A. Any time the vehicle is parkedExplanation
In air brake vehicles, the parking brakes should be used any time the vehicle is parked. This is because the parking brakes are designed to hold the vehicle in place and prevent it from rolling or moving when it is not in use. Using the parking brakes whenever the vehicle is parked ensures that it remains stationary and does not pose a safety risk.Rate this question:
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- 18.
The modulating control valve allows you to control the
- A.
Front brakes
- B.
Amount of air pressure in the brake system
- C.
Spring brakes
- D.
All of the above
Correct Answer
C. Spring brakesExplanation
The modulating control valve allows you to control the amount of air pressure in the brake system. This means that it can regulate the pressure going to the spring brakes, which are a type of brake used in heavy vehicles. Therefore, the correct answer is "spring brakes" because the modulating control valve is responsible for controlling the air pressure in these brakes.Rate this question:
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- 19.
The brake system that applies and releases the brakes when the driver uses the brake pedal is the _____ brake system
- A.
Service
- B.
Emergency
- C.
Parking
- D.
All of the above
Correct Answer
A. ServiceExplanation
The brake system that applies and releases the brakes when the driver uses the brake pedal is known as the service brake system. This system is responsible for the normal braking function of a vehicle, allowing the driver to slow down or stop the vehicle when necessary. The emergency brake system, also known as the parking brake system, is a separate system that is used to hold the vehicle in place when parked or during an emergency situation. Therefore, the correct answer is service.Rate this question:
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- 20.
Some air brake systems have an alcohol evaporator. What may happen if you don't keep the unit filled with alcohol?
- A.
Ice may from on the brake drums and warp them
- B.
The S-cam may not rotate back when you release the brake pedal
- C.
Ice may form in the air storage tanks and cause the brakes to fail
- D.
All of the above
Correct Answer
C. Ice may form in the air storage tanks and cause the brakes to failExplanation
If the alcohol evaporator in an air brake system is not kept filled with alcohol, ice may form in the air storage tanks. This can cause the brakes to fail because the ice can block the flow of air through the system, preventing the brakes from properly engaging and disengaging. This can lead to a loss of braking power and potentially dangerous situations on the road.Rate this question:
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- 21.
Under normal conditions, to engage the parking brake the driver must first
- A.
Be sure that the air brake system is fully pressurized
- B.
Turn off the engine
- C.
Let the air out of the spring brakes
- D.
All of the above
Correct Answer
C. Let the air out of the spring brakesExplanation
Under normal conditions, to engage the parking brake, the driver must let the air out of the spring brakes. This is because the parking brake in a commercial vehicle is typically controlled by the spring brakes, which are part of the air brake system. Releasing the air from the spring brakes allows the brakes to engage and hold the vehicle in place when parked. It is important to ensure that the air brake system is fully pressurized and the engine is turned off before engaging the parking brake, but these steps are not directly related to letting the air out of the spring brakes.Rate this question:
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- 22.
During normal driving, spring brakes are usually held back by
- A.
Air pressure
- B.
Spring pressure
- C.
Bolts
- D.
All of the above
Correct Answer
A. Air pressureExplanation
During normal driving, spring brakes are usually held back by air pressure. Air pressure is used to keep the spring brakes disengaged so that the vehicle can move freely. When the air pressure is released, the spring brakes engage and apply pressure to the brakes, stopping the vehicle. This system ensures that the brakes are only activated when needed and allows for smooth and efficient driving.Rate this question:
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- 23.
If your vehicle has an alcohol evaporator, every day during cold water you should
- A.
Check the oil for alcohol content
- B.
Check and fill the alcohol level
- C.
Change the alcohol from a new bottle
- D.
All of the above
Correct Answer
B. Check and fill the alcohol levelExplanation
The correct answer is "check and fill the alcohol level." If your vehicle has an alcohol evaporator, it is important to regularly check and maintain the alcohol level. This is because the alcohol evaporator helps to prevent the fuel system from freezing during cold weather. By checking and filling the alcohol level, you ensure that the evaporator is functioning properly and that your vehicle's fuel system is protected from freezing.Rate this question:
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- 24.
The most common type of foundation brake found on heavy vehicles is the
- A.
Dis brake
- B.
Wedge drum
- C.
S-cam drum
- D.
None of the above
Correct Answer
C. S-cam drumExplanation
The S-cam drum is the most common type of foundation brake found on heavy vehicles. This type of brake utilizes a rotating S-shaped cam to push the brake shoes against the drum, creating friction and stopping the vehicle. The S-cam drum brake system is known for its durability and effectiveness in heavy-duty applications, making it the preferred choice for heavy vehicles. The other options, such as the disc brake and wedge drum, are less commonly used in this context.Rate this question:
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- 25.
A supply pressure gauge tells you how much pressure is in the
- A.
Tractor brake lines
- B.
Air tanks
- C.
Trailer brake line
- D.
None of the above
Correct Answer
B. Air tanksExplanation
A supply pressure gauge is used to measure the amount of pressure present in a system. In this case, the answer states that the supply pressure gauge tells you how much pressure is in the air tanks. This means that the gauge is specifically designed to measure the pressure in the air tanks and not in any other component such as the tractor brake lines or the trailer brake line. Therefore, the correct answer is air tanks.Rate this question:
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- 26.
The air compressor governor controls
- A.
When air is pumped into the air storage tanks
- B.
The speed of the air compressor
- C.
Air pressure applied to the brake
- D.
None of the above
Correct Answer
A. When air is pumped into the air storage tanksExplanation
The air compressor governor controls the release of air into the air storage tanks. As air is pumped into the tanks, the governor regulates the speed of the air compressor to maintain a consistent pressure. This pressure is then applied to the brakes, allowing for effective braking in vehicles. Therefore, the correct answer is "when air is pumped into the air storage tanks."Rate this question:
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- 27.
It is not safe to drive a vehicle that has brake drums (or discs) with cracks or that are thinner than the manufacturer's specifications, generally this will be ____ inch
- A.
1/2
- B.
1/3
- C.
1/4
- D.
All of the above
Correct Answer
C. 1/4Explanation
Driving a vehicle with brake drums or discs that have cracks or are thinner than the manufacturer's specifications is unsafe because it can compromise the braking system's effectiveness. This can lead to reduced braking power, longer stopping distances, and potentially even brake failure. Therefore, it is important to ensure that brake drums or discs are not cracked and meet the manufacturer's recommended thickness, which is generally 1/4 inch.Rate this question:
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- 28.
Your truck or bus has a dual air brake system. If a low air pressure warning comes on for only one system, what should you do?
- A.
Stop and safely park. Continue only after the system is fixed
- B.
Reduce your speed and test the remaining system while driving
- C.
Reduce your speed and drive the the nears garage for repairs
- D.
All of the above
Correct Answer
A. Stop and safely park. Continue only after the system is fixedExplanation
If the low air pressure warning comes on for only one system in a dual air brake system, it is important to stop and safely park the truck or bus. Continuing to drive without fixing the system can lead to brake failure and potential accidents. Therefore, the correct course of action is to wait until the system is fixed before continuing the journey.Rate this question:
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- 29.
If the spring brakes are on, when should you push the brake pedal?
- A.
Never
- B.
Only when driving down a hill
- C.
Only on a slippery road
- D.
All of the above
Correct Answer
A. NeverExplanation
When the spring brakes are engaged, it means that the brakes are already applied automatically. Therefore, there is no need to push the brake pedal as it will not have any effect. Pushing the brake pedal while the spring brakes are on can potentially damage the braking system.Rate this question:
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Mar 22, 2023Quiz Edited by
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Oct 24, 2016Quiz Created by
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