Questions and Answers
Modern air brake systems combine three different systems. They are the service brakes, the parking brakes, and the _____
emergency
The driver must be able to see a warning that is given before air pressure in the service air tanks falls below _____ psi.
60 psi
The brake pedal in an air brake system:
Controls the air pressure applied on the brakes
Air braking takes more time than hydraulic braking because air:
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If your vehicle has an alcohol evaporator, it is there to:
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If your truck has dual parking controls, you can use pressure from a separate tank to:
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To check the free play of manual slack adjusters on S-cam brakes, you should park on:
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Of the choices below, the first thing to do when a low air pressure warning comes on is:
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The air compressor governor controls:
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The braking power of the spring brakes:
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All vehicles equipped with air brakes have:
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If you must make an emergency stop, brake so you:
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If you do not have automatic tank drains, how often should you drain the oil and water from the bottom of compressed air storage tanks?
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The application pressure gauge shows how much air pressure you:
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Your brakes are fading when:
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If your vehicle has an alcohol evaporator, every day during cold weather you should:
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Why should you drain water from compressed air tanks?
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Your vehicle has a dual air brake system. If a low air pressure warning comes on for the secondary system, you should:
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During normal driving, spring brakes are usually held back by:
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In air brake vehicles, the parking brakes should be used:
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Emergency stab braking is when you:
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A straight truck air brake system should not leak at a rate of more than _____ psi per minute with the engine off and the brakes released.
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The air loss for a straight truck or bus with the engine off and the brakes on should not be more than:
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The supply pressure gauge shows how much pressure:
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Before driving a vehicle with a dual air system, allow time for the air compressor to build up a minimum of _____ psi pressure in both the primary and secondary system.
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Total stopping distance for air brakes is longer than that of hydraulic brakes due to:
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The most common type of foundation brake found on heavy vehicles is the:
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Which of the following makes total stopping distance longer for air brakes than for hydraulic brakes:
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If the air compressor develops a leak, what keeps the air in the tanks?
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Study Notes
Air Brake Systems
- Modern air brake systems comprise three systems: service brakes, parking brakes, and emergency brakes.
- All vehicles equipped with air brakes have a supply pressure gauge to monitor system health.
Air Pressure and Warnings
- A warning must alert the driver before air pressure in the service air tanks drops below 60 psi.
- The air compressor governor regulates when air is pumped into the brake system.
- If a low air pressure warning occurs, the immediate action is to stop and safely park the vehicle.
Brake Functionality
- The brake pedal controls the air pressure applied to the brakes, influencing braking performance.
- Spring brakes rely on air pressure during normal driving and provide braking power dependent on the adjustment of service brakes.
Safety Measurements
- When making an emergency stop, brake to maintain vehicle direction, allowing for steering.
- If air compressor leaks arise, a one-way check valve retains air in the tanks, ensuring continued functionality.
Maintenance Protocols
- Drain oil and water from compressed air storage tanks daily if automatic drains are absent to prevent freeze-related brake failures.
- Check the alcohol level in the alcohol evaporator during cold weather and replenish if necessary to mitigate ice in brake valves.
Brake Testing and Adjustments
- Check manual slack adjusters by parking on level ground, blocking the wheels, and disengaging parking brakes.
- Total stopping distance for air brakes is extended due to brake lag, a common characteristic compared to hydraulic systems.
- A straight truck's air brake system should not leak more than 2 psi per minute (engine off, brakes released).
Parking and Control
- Use parking brakes whenever the vehicle is parked, enhancing safety.
- For dual air brake systems, if the secondary system indicates low air pressure, bring the vehicle to a stop and only resume operation after repairs.
Braking Techniques
- Emergency stab braking involves brisk full braking, releasing when wheels lock, then re-engaging when wheels regain traction.
- The application pressure gauge indicates the air pressure being applied to the brakes, crucial for effective stopping.
Temperature Considerations
- Water in compressed air tanks can freeze, potentially leading to brake failure in cold conditions, necessitating regular drainage.
Brake Types
- The S-cam drum brake is the most common foundation brake in heavy vehicles, indicative of its reliability in diverse driving situations.
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Description
This quiz covers the essential components and functionality of modern air brake systems, including service, parking, and emergency brakes. It delves into the importance of air pressure management and safety measures during braking. Test your knowledge on how these systems operate and their critical safety features.
