CDL Air Brakes Study Guide #1

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If oil and water collects in the air tanks what can happen to the brakes? *

1 point

The brakes could heat up

The brakes could fail

The brakes could lock up

Your truck has a dual air system and one of the system loses its pressure. What will happen? *

1 point

Brake drums will not be fully pressurized

Either the front or back brake will not be fully operational

The manual slack adjusters of the S-cam brakes will not be set properly

The spring brakes used in the chambers in a straight truck will bring you to a stop when air pressure drops below ___ PSI. *

1 point

100

If your truck or bus has dual parking control valves, you can use pressure from a separate tank to: *

1 point

Balance the service brake system when you are parked

Release the spring emergency/parking brakes to move a short distance

Stay parked twice as long without using up service air pressure

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? *

1 point

After every four hours of service

At the end of each day of driving

Once a week

What factors can cause brakes to fade or fail? *

1 point

Not pressing the brake pedal hard enough

Overheating, low air pressure, and not relying on the engine braking effect

Not taking your foot off the accelerator

Why drain water from the compressed air tanks? *

1 point

To keep from fouling the air compressor oil

Water can freeze in cold weather and cause brake failure

The low boiling point of water reduces braking power

The driver must be able to see a warning when air pressure in the service air tanks falls below ___ PSI. *

1 point

The air brake lag distance at 55 mph on dry pavement adds about ___ feet. *

1 point

The most common type of foundation brakes found on heavy vehicles is the: *

1 point

Wedge drum

S-cam drum

Disc drum

The use of brakes on a long steep downgrade is only a supplement to the braking effect of the engine. *

1 point

True

False

Oil and water usually collect in compressed air tanks. If you do not have an automatic tank drain, when should you drain the air tanks? *

1 point

After every working day

After every four hours of service

Once a week

Why should you be in the proper gear before starting down a hill? *

1 point

So you only have to apply the brake just hard enough to feel a definite slowdown

So you can coast downhill

So you can go through the gears on the way down

The safety valve is set to automatically reduce pressure at ___ PSI. *

1 point

150

100

The braking power of the spring brakes: *

1 point

Is not affected by the condition of the service brakes

Increases when the service brakes are hot

Depends on the service brakes being in adjustment

You should know that your brakes are fading when: *

1 point

Pressure on the brake pedal is released and speed increases

You have to apply the brake pedal harder to control speed on a downgrade

The brake feels spongy when pressure is applied

What is the purpose of an alcohol evaporator? *

1 point

So you don’t have to drain the air tanks as often

To have a drink available if you get thirsty

To reduce the risk of ice in the brake valves and other parts in cold weather

The application pressure gauge shows how much pressure you have: *

1 point

In the tanks

In a modulating control valve

When you are applying the brakes

If you must make an emergency stop, brake so you: *

1 point

Use the hand-brake before the brake pedal

Can steer and your vehicle stays in a straight line

Use the full power of the brakes to lock them

To check the brake slack on S-cam brakes you should: *

1 point

Park on level ground, chock the wheels, and release the parking brake

Stop on level ground and apply the parking brakes

Park on level ground and drain off air pressure before adjusting

What is another name for controlled braking? *

1 point

Steady braking

Squeeze braking

Hard braking

If the air compressor should develop a leak, what keeps the air in the tanks? *

1 point

The tractor protection valve

The emergency relay valve

The one-way check valve

Excessive use of the service brakes results in overheating, which can lead to: *

1 point

Expansion of the brake drums

Increase contact between the brake drums and springs

Proper adjustment of S-cam

During normal driving, spring brakes are usually held back by: *

1 point

Air pressure

Springs

Bolts and braces

The driver must be able to see a low pressure warning, which comes on before the pressure in the service air tank falls below: *

1 point

60 PSI

80 PSI

100 PSI

The air compressor stops pumping air at what PSI? *

1 point

125

100

150

The air brake system for a straight truck or bus should not leak at a rate of more than ___ PSI per minute with the engine off and the brakes released. *

1 point

To make an emergency stop with air brakes using the stab braking method, you should: *

1 point

Pump the brake pedal rapidly and lightly

Brake hard until the wheels lock, and then get off the brakes for as much time as the wheels were locked

Press on the brake pedal as hard as you can, release the brakes when the wheels lock, put on the brakes again when the wheels start rolling

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