Podcast
Questions and Answers
When should you drain the air tanks?
When should you drain the air tanks?
After every working day
What is the S-cam used for?
What is the S-cam used for?
To put on the brakes
What makes the total stopping distance for air brakes longer than hydraulic brakes?
What makes the total stopping distance for air brakes longer than hydraulic brakes?
Brake lag distance
What is the brake system that applies and releases the brakes when the driver uses the brake pedal?
What is the brake system that applies and releases the brakes when the driver uses the brake pedal?
What should you do to make an emergency stop using the stab braking method?
What should you do to make an emergency stop using the stab braking method?
Brake lag distance at 55 mph is ______ feet.
Brake lag distance at 55 mph is ______ feet.
If your vehicle has an alcohol evaporator, what is its purpose?
If your vehicle has an alcohol evaporator, what is its purpose?
What can legally hold a parking or emergency brake in position for a truck, truck tractor, or bus?
What can legally hold a parking or emergency brake in position for a truck, truck tractor, or bus?
The braking power of the spring brakes depends on what?
The braking power of the spring brakes depends on what?
What should you do before leaving the vehicle unattended?
What should you do before leaving the vehicle unattended?
Under what conditions are front-wheel brakes good?
Under what conditions are front-wheel brakes good?
What happens if the air tanks are not drained?
What happens if the air tanks are not drained?
What does an anti-lock braking system (ABS) do?
What does an anti-lock braking system (ABS) do?
What can cause brakes to fade or fail?
What can cause brakes to fade or fail?
If your vehicle has a properly functioning dual air brake system, the air pressure should build from 85 to 100 psi within ______ seconds.
If your vehicle has a properly functioning dual air brake system, the air pressure should build from 85 to 100 psi within ______ seconds.
The air compressor will stop pumping air to the air brakes at ______ psi.
The air compressor will stop pumping air to the air brakes at ______ psi.
What can excessive heat from overuse of the service brakes cause?
What can excessive heat from overuse of the service brakes cause?
What is the typical air brake system fully charged at?
What is the typical air brake system fully charged at?
During normal driving, spring brakes are normally held back by?
During normal driving, spring brakes are normally held back by?
What should you do during your final air brake check if the air pressure does not build up fast enough?
What should you do during your final air brake check if the air pressure does not build up fast enough?
To test the static air leakage rate, what should you do?
To test the static air leakage rate, what should you do?
What do air brakes use?
What do air brakes use?
What happens when you press the brake pedal?
What happens when you press the brake pedal?
What does the air compressor governor control?
What does the air compressor governor control?
What should you do when a low air pressure signal comes on?
What should you do when a low air pressure signal comes on?
What must air brake-equipped vehicles have?
What must air brake-equipped vehicles have?
What is the minimum leakage rate for brake drums?
What is the minimum leakage rate for brake drums?
If the low pressure warning signal is not working, what might happen?
If the low pressure warning signal is not working, what might happen?
In the event of a brake system failure, what does the emergency brake system use to stop the vehicle?
In the event of a brake system failure, what does the emergency brake system use to stop the vehicle?
What should you never do if the spring brakes are on?
What should you never do if the spring brakes are on?
How do you know your brakes are fading?
How do you know your brakes are fading?
What does a converter dolly with anti-lock brakes (ABS) need to have?
What does a converter dolly with anti-lock brakes (ABS) need to have?
Which of the following is the most important thing about hard braking?
Which of the following is the most important thing about hard braking?
In controlled braking, you should ?
In controlled braking, you should ?
What could happen to the brakes if oil and water collect in the air tanks?
What could happen to the brakes if oil and water collect in the air tanks?
Why is it called an S-cam?
Why is it called an S-cam?
What should you do to test the air service brakes?
What should you do to test the air service brakes?
When can you leave your truck unattended without first applying the parking brakes or chocking the wheels?
When can you leave your truck unattended without first applying the parking brakes or chocking the wheels?
If your truck or bus has a dual parking control valve, what does it mean?
If your truck or bus has a dual parking control valve, what does it mean?
The brake pads should be ______ for the brakes to be on.
The brake pads should be ______ for the brakes to be on.
The application pressure gauge shows how much air pressure?
The application pressure gauge shows how much air pressure?
What keeps the air in the tanks if the air compressor develops a leak?
What keeps the air in the tanks if the air compressor develops a leak?
Brake drums must not have cracks longer than ______ the width of the fractioned area.
Brake drums must not have cracks longer than ______ the width of the fractioned area.
What is the maximum acceptable leakage rate per minute for single vehicles?
What is the maximum acceptable leakage rate per minute for single vehicles?
How do brakes work on a long, steep downgrade?
How do brakes work on a long, steep downgrade?
How would you check your truck's slack adjusters?
How would you check your truck's slack adjusters?
What does the parking brake control do?
What does the parking brake control do?
What could happen if the low pressure warning signal is not working?
What could happen if the low pressure warning signal is not working?
If your vehicle has dual air brake systems, what happens if one system loses air pressure?
If your vehicle has dual air brake systems, what happens if one system loses air pressure?
Under ideal conditions, what is the average stopping distance for a bus or truck equipped with air brakes traveling at 55 mph?
Under ideal conditions, what is the average stopping distance for a bus or truck equipped with air brakes traveling at 55 mph?
What do modern air brake systems combine?
What do modern air brake systems combine?
What should you do to check the free play of manual slack adjusters on S-cam brakes?
What should you do to check the free play of manual slack adjusters on S-cam brakes?
If a low air pressure warning comes on for only one system in a dual air brake system, what should you do?
If a low air pressure warning comes on for only one system in a dual air brake system, what should you do?
If your vehicle has an alcohol evaporator, what should you do during cold weather every day?
If your vehicle has an alcohol evaporator, what should you do during cold weather every day?
With S-cam drum brakes, when the brake chamber fills with air, air pressure pushes the push rod out, moving the ______ and thus rotating the ______.
With S-cam drum brakes, when the brake chamber fills with air, air pressure pushes the push rod out, moving the ______ and thus rotating the ______.
In which position should you NOT apply the parking brake?
In which position should you NOT apply the parking brake?
What can cause brakes to fail or fade?
What can cause brakes to fail or fade?
If you need to stop quickly and your vehicle lacks anti-lock brakes (ABS), what methods can you use?
If you need to stop quickly and your vehicle lacks anti-lock brakes (ABS), what methods can you use?
Tractor and straight truck spring brakes will come fully on when air pressure drops to a range of ______.
Tractor and straight truck spring brakes will come fully on when air pressure drops to a range of ______.
What does the modulating control valve allow you to control?
What does the modulating control valve allow you to control?
What should air loss in a straight truck or bus not exceed with the engine off and the brakes applied?
What should air loss in a straight truck or bus not exceed with the engine off and the brakes applied?
What activates the stop switch?
What activates the stop switch?
A straight truck or bus air brake system should not leak at a rate of more than ______ psi per minute with the engine off and the brakes released.
A straight truck or bus air brake system should not leak at a rate of more than ______ psi per minute with the engine off and the brakes released.
What is required for vehicles with air brakes?
What is required for vehicles with air brakes?
Slack adjusters should not have any more than ______ of play.
Slack adjusters should not have any more than ______ of play.
What is the best way to test your vehicle's low air pressure warning system?
What is the best way to test your vehicle's low air pressure warning system?
Which vehicle must have low air pressure warning signals?
Which vehicle must have low air pressure warning signals?
On a long or steep downgrade, once you have reached your safe speed, brake until you are traveling ______ lower than the safe speed.
On a long or steep downgrade, once you have reached your safe speed, brake until you are traveling ______ lower than the safe speed.
To apply the parking brake under normal conditions, you should?
To apply the parking brake under normal conditions, you should?
What are slack adjusters?
What are slack adjusters?
Why does air braking take more time than hydraulic braking?
Why does air braking take more time than hydraulic braking?
What does the brake pedal in an air brake system control?
What does the brake pedal in an air brake system control?
What does the tractor protection valve do?
What does the tractor protection valve do?
What is the first thing you should do if the low air pressure warning comes on?
What is the first thing you should do if the low air pressure warning comes on?
When should you use the parking brake?
When should you use the parking brake?
What does the supply pressure gauge show?
What does the supply pressure gauge show?
Which of the following is not a part of the drum brake?
Which of the following is not a part of the drum brake?
Study Notes
General Air Brake Knowledge
- Oil and water can collect in compressed air tanks; drain them after every working day if no automatic tank drain is present.
- The S-cam is a critical component used to apply the brakes.
- Total stopping distance for air brakes is extended due to brake lag distance.
Brake Systems
- The service brake system is responsible for applying and releasing brakes when the driver uses the brake pedal.
- To make an emergency stop using air brakes, utilize the stab braking method correctly to avoid wheel lock.
- Brake lag distance at 55 mph is approximately 32 feet.
Air Brake Maintenance and Function
- Alcohol evaporators help prevent ice formation in air brake valves during cold weather.
- Spring pressure is legally allowed to hold a parking or emergency brake in position for heavy vehicles.
- Proper adjustment of the service brake affects the braking power of the spring brakes.
Safety and Operational Procedures
- Always set the parking brake, remove the keys, and chock the wheels before leaving a vehicle unattended.
- Front-wheel brakes perform well under all weather conditions and should be checked consistently.
- Failing to drain air tanks can lead to brake failure due to freezing water.
Anti-lock Systems and Braking Techniques
- An anti-lock braking system (ABS) engages to prevent wheel lock-up.
- Common causes of brake failure or fade include excessive service brake use, inadequate engine braking reliance, and improperly adjusted brakes.
- If an ABS fails, normal brake function remains, but repairs should be made promptly.
Vehicle Specifications and Conditions
- Dual air brake systems should build air pressure from 85 to 100 psi in about 45 seconds.
- The air compressor governor stops pumping air at 125 psi.
- The air pressure in a typical air brake system should be fully charged at 125 psi.
Braking Mechanics and Emergency Procedures
- Maintain control and steer to stay in a straight line during emergency stops.
- Vehicles must have a supply pressure gauge to monitor air pressure.
- In case of low air pressure signals, safely stop and park as soon as possible.
Operational Limits and Regulations
- Brakes should not lock up for prolonged periods during hard braking.
- Always check for a proper function of the low air pressure warning signal to avoid sudden emergency braking situations.
- Slack adjusters should be maintained at no more than 1/2 inch of play and checked regularly for safety.
Testing and Performance Standards
- To test static air leakage, turn off the engine, release the parking brake, and allow the air system to settle.
- Acceptable leakage rates for single vehicles is 3 psi per minute, while combination vehicles allow for 4 psi.
- On steep downgrades, brake until your speed is 5 mph below the determined safe speed.
Additional Considerations
- Be aware of the risks of overheating and the importance of engine braking to ensure effective brake operation.
- The application pressure gauge displays the amount of air pressure applied to the brakes.
- Routine checks on brake components, including slack adjusters and brake drums, ensure vehicle safety.
Studying That Suits You
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Description
Test your knowledge of Alabama CDL general concepts with these flashcards. This quiz covers essential topics such as air brake maintenance, braking systems, and safety practices. Perfect for those preparing for their Commercial Driver's License in Alabama.
