Texas CDL Air Brakes Flashcards

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Questions and Answers

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?

After every working day.

Why drain water from the compressed air tanks?

Water can freeze in cold weather and cause brake failure.

Air brake equipped vehicles must have:

A supply pressure gauge and warning signal when psi drops below 60. Signup and view all the answers

What can legally hold a parking or emergency brake in position for a truck, truck tractor or bus?

Spring pressure. Signup and view all the answers

What makes the total stopping distance for air brakes longer than that for hydraulic brakes?

Brake lag distance. Signup and view all the answers

The first thing you should do when the low air pressure warning comes on?

Stop and safely park ASAP. Signup and view all the answers

The braking power of the spring brakes depends on the adjustment of the:

Service brakes. Signup and view all the answers

The air compressor governor controls what?

When air is pumped into the air tanks. Signup and view all the answers

The application pressure gauge shows the driver how much pressure:

Is being applied to the brakes. Signup and view all the answers

When you apply pressure to the brake pedal, you are:

Pushing against a spring and against air pressure to the brakes. Signup and view all the answers

The air compressor is connected to the engine through:

Gears or a V-belt. Signup and view all the answers

Which type of brake is the most common in commercial vehicles?

S-cam brake. Signup and view all the answers

An application pressure gauge shows how much air pressure you are applying to the brakes.

True Signup and view all the answers

All vehicles with air brakes are required to have a low pressure warning signal. This could be:

A red light Signup and view all the answers

To test service brakes you should:

Release the parking brake, move forward slowly and depress brakes. Signup and view all the answers

Stab braking occurs when you:

<ol> <li>Press on a brake pedal as hard as you can. 2. Release the brakes when the wheels lock up. 3. Apply the brakes when the wheels start rolling.</li> </ol> Signup and view all the answers

Air brakes take longer to stop than hydraulic brakes because:

It takes longer for the air to flow through the lines. Signup and view all the answers

The proper way to go down long grades is to:

Apply brakes just hard enough to reduce speed to 5 mph below safe speed then release until back to safe speed and repeat the process. Signup and view all the answers

When should you avoid using the parking brake?

When the brakes are hot. Signup and view all the answers

If your vehicle has an alcohol evaporator, every day during cold weather you should:

Check and fill the alcohol level. Signup and view all the answers

During normal driving, spring brakes are usually held back by what?

Air pressure. Signup and view all the answers

In air brake vehicles, the parking brakes should be used when?

Whenever the vehicle is parked. Signup and view all the answers

The brake pedal in an air brake system does what?

Controls the air pressure applied to put on the brakes. Signup and view all the answers

If your bus has dual parking control valves it means that you can use pressure from a separate tank to:

Release the spring brakes to move a short distance. Signup and view all the answers

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.

2 Signup and view all the answers

An alcohol evaporator does what?

Reduces the risk of ice in the air brake valves in cold weather. Signup and view all the answers

If you must make an emergency stop, you should brake so that you:

Stay in a straight line and can steer. Signup and view all the answers

Air loss should not be more than ___ with the engine off and brakes released.

2 psi per minute Signup and view all the answers

Stab braking

Brake as hard as you can, get off the brakes when wheels are locked, and get back on the brakes when wheels start rolling again. Signup and view all the answers

How do you know when your brakes are fading?

You have to push harder on the brake pedal to control your speed on a downgrade. Signup and view all the answers

To check the free play of manual slack adjusters on S-cam brakes you should:

Park on level ground, chock wheels, and release parking brake. Signup and view all the answers

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!