Podcast
Questions and Answers
Air brake systems combine what three different systems?
Air brake systems combine what three different systems?
- Emergency brakes (correct)
- Service brakes (correct)
- Parking brakes (correct)
- Transmission brakes
When should you drain the air tanks?
When should you drain the air tanks?
After every working day.
Why drain water from the compressed air tanks?
Why drain water from the compressed air tanks?
Water can freeze in cold weather and cause brake failure.
Air brake equipped vehicles must have:
Air brake equipped vehicles must have:
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?
What makes the total stopping distance for air brakes longer than that for hydraulic brakes?
What makes the total stopping distance for air brakes longer than that for hydraulic brakes?
The first thing you should do when the low air pressure warning comes on?
The first thing you should do when the low air pressure warning comes on?
The braking power of the spring brakes depends on the adjustment of the:
The braking power of the spring brakes depends on the adjustment of the:
The air compressor governor controls what?
The air compressor governor controls what?
The application pressure gauge shows the driver how much pressure:
The application pressure gauge shows the driver how much pressure:
When you apply pressure to the brake pedal, you are:
When you apply pressure to the brake pedal, you are:
The air compressor is connected to the engine through:
The air compressor is connected to the engine through:
Which type of brake is the most common in commercial vehicles?
Which type of brake is the most common in commercial vehicles?
An application pressure gauge shows how much air pressure you are applying to the brakes.
An application pressure gauge shows how much air pressure you are applying to the brakes.
All vehicles with air brakes are required to have a low pressure warning signal. This could be:
All vehicles with air brakes are required to have a low pressure warning signal. This could be:
To test service brakes you should:
To test service brakes you should:
Stab braking occurs when you:
Stab braking occurs when you:
Air brakes take longer to stop than hydraulic brakes because:
Air brakes take longer to stop than hydraulic brakes because:
The proper way to go down long grades is to:
The proper way to go down long grades is to:
When should you avoid using the parking brake?
When should you avoid using the parking brake?
If your vehicle has an alcohol evaporator, every day during cold weather you should:
If your vehicle has an alcohol evaporator, every day during cold weather you should:
During normal driving, spring brakes are usually held back by what?
During normal driving, spring brakes are usually held back by what?
In air brake vehicles, the parking brakes should be used when?
In air brake vehicles, the parking brakes should be used when?
The brake pedal in an air brake system does what?
The brake pedal in an air brake system does what?
If your bus has dual parking control valves it means that you can use pressure from a separate tank to:
If your bus has dual parking control valves it means that you can use pressure from a separate tank to:
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.
An alcohol evaporator does what?
An alcohol evaporator does what?
If you must make an emergency stop, you should brake so that you:
If you must make an emergency stop, you should brake so that you:
Air loss should not be more than ___ with the engine off and brakes released.
Air loss should not be more than ___ with the engine off and brakes released.
Stab braking
Stab braking
How do you know when your brakes are fading?
How do you know when your brakes are fading?
To check the free play of manual slack adjusters on S-cam brakes you should:
To check the free play of manual slack adjusters on S-cam brakes you should:
Study Notes
Air Brake Systems
- Air brake systems consist of three main components: service brakes, parking brakes, and emergency brakes.
- Most commercial vehicles commonly use S-cam brakes.
Maintenance and Operations
- Drain air tanks after every working day to prevent water accumulation.
- Water in compressed air tanks can freeze and lead to brake failure in cold weather.
Indicators and Signals
- Vehicles with air brakes must have a supply pressure gauge and a warning signal when pressure drops below 60 psi.
- Low-pressure warning signals can be a red light, wig wag mechanical arm, or buzzer.
Braking Performance
- Total stopping distance for air brakes is longer than hydraulic brakes due to brake lag distance, which is the time taken for air to travel through the lines.
- Stab braking technique involves pressing the brake pedal hard, releasing it when wheels lock up, and reapplying when wheels start to roll again.
Safety Measures
- Upon activation of the low air pressure warning, the immediate action is to stop and park safely as soon as possible.
- Spring brakes provide braking power and rely on service brake adjustment.
- Avoid using the parking brake when brakes are hot to prevent damage or failure.
Testing and Adjustments
- Test service brakes by releasing the parking brake, moving forward slowly, and then applying the brakes.
- The correct procedure for descending long grades is to apply the brakes to reduce speed by 5 mph, then release the brakes until returning to a safe speed.
Air Compressor and Pressure Management
- The air compressor governor controls when air is pumped into the air tanks, maintaining appropriate pressure levels.
- During normal driving, air pressure holds back the spring brakes.
Emergency Protocols
- To perform an emergency stop, brake firmly while ensuring the vehicle remains in a straight line to maintain steering control.
- If dual parking control valves are present in a bus, they can utilize pressure from a separate tank to release spring brakes for short movements.
Leak Assessment
- A straight truck or bus should not leak air at a rate exceeding 2 psi per minute when the engine is off and brakes are released.
- Air loss during a similar condition should also not exceed 2 psi per minute.
Additional Information
- An alcohol evaporator is vital in cold weather as it reduces ice formation in air brake valves.
- To ensure proper adjustment, check free play of manual slack adjusters on S-cam brakes by parking on level ground and releasing the parking brake.
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Description
Test your knowledge on the essentials of air brake systems with these flashcards. Learn about service, parking, and emergency brakes, as well as important maintenance practices like draining air tanks. Perfect for those preparing for their Texas CDL test!
