Air Brakes #1

A straight truck air brake system should not leak at a rate of more than _______ psi per minute with the engine off and the brake on.

Your brakes are fading when:

You release pressure on the brake pedal and speed increases.

Less pressure is needed on the brake pedal for each stop.

You have to push harder on the brake pedal to control your speed on a downgrade.

The brake pedal feels spongy when you apply pressure.

The supply pressure gauge shows how much pressure:

Is going to the brake chambers

You have used in this trip

Is in the air tanks

The air can take

The brake system that applies and releases the brakes when the driver uses the brake pedal is the _______ brake system.

Emergency

Parking

Service

None of the above

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

Change the alcohol from a new bottle

Check the oil for alcohol content

Check and fill the alcohol level

Clean the air filter with alcohol

Why should you drain water from compressed air tanks?

To make room for the oil that should be there.

Water cools the compressor too much.

Water can freeze in cold weather and cause brake failure.

The boiling point reduces brake power.

On long downhill grades, experts recommend using a low gear and light, steady pedal pressure instead of on-again, off-again braking. Why?

Air usage is less with light steady pressure.

Brake linings do not heat up as much with light pressure.

You can keep vehicle speed constant in a low gear with light, steady, pressure.

All of the above

Your truck or bus has a dual air brake system. If a low air pressure warning comes on for only one system, what should you do?

Reduce your speed, and test the remaining system while under way

Continue at normal speed. No action is needed when only one system fails.

Stop right away and safely park. Continue only after the system is fixed.

Reduce your speed, and drive to the nearest garage for repairs

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

Spring pressure

Air pressure

Bolts or clamps

Centrifugal force

Total stopping distance for air brakes is longer than that for hydraulic brakes due to __________ distance.

Reaction

Perception

Brake lag

Effective braking

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

Disc

Wedge drum

S+cam drum

None of the above

With air brake vehicles, the parking brakes should be used:

Only during pre and post-trip inspections

To hold your speed when going downhill

As little as possible

Whenever you leave the vehicle unattended

For emergency stab braking, you should:

Press hard on the brake pedal and apply full hand valve until you stop

Brake hard until the wheels lock, then release

Pump the brake pedal rapidly and lightly

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

Parking or emergency brakes of trucks and buses can be legally held on by _________ pressure.

Fluid

Atmospheric

Spring

Air

The driver must be able to see a low air pressure warning which comes on before pressure in the service air tanks falls below ________ psi.

If your vehicle has an alcohol evaporator, it is there to:

Rid the wet tank of alcohol that condenses and sits at the bottom

Eliminate the need for daily tank draining

Boost tank pressure the same way that turbochargers boost engines

Reduce the risk of ice in air brake valves in cold weather

The brake pedal in an air brake system:

Controls the air pressure applied to put on the brakes

Controls the speed of the air compressor

Is connected to slack adjusters by a series of rods and linkages

Is seldom used, compared to hydraulic systems

Separate air tanks allows the driver of a heavy vehicle to:

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

Brake harder if the main tank is getting low

Balance the service brake system when you are parked

Stay parked twice as long without using up service air pressure

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

A slight grade, release the parking brakes, and apply the service brakes, watching for vehicle movement

Level ground and drain off air pressure before checking the adjustment

Level ground and apply the parking brakes

Level ground, chock the wheels, and release the parking brakes

The most important thing to do when a low air pressure warning comes on is:

Adjust the brake pedal for more travel

Stop and safely park as soon as possible.

Downshift

Upshift

The air compressor governor controls:

When air is pumped into the air tanks

When the brake chambers release pressure

Air pressure applied to the brakes

The speed of the air compressor

The braking power of the spring brakes:

Is not affected by the condition of the service brakes

Can only be tested by highly+trained brake service people

Increases when the service brakes are hot

Depends on the service brakes being in adjustment

All air brake equipped vehicles have:

At least one brake heater

A backup hydraulic system

An air use gauge

A supply pressure gauge

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

Use the hand brake before the brake pedal

Use the full power of the brakes to lock them

Can steer and your vehicle stays in a straight line

Do not need to worry about steering

Air Brakes #1

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