air brakes

61問 • 2年前

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

air pressure

The brake pedal in an air brake system:

controls the air pressure applied to put on the brakes

The brake system that applies and releases the brakes when the driver uses the brake pedal is what system?

service system

All air braked equipped vehicles must have what?

a supply pressure gauge

If your truck or bus has a dual parking control valve, you can use pressure fron another tank to:

release the spring brakes to move the vehicle in an emergency

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

s-cam drum brake

Parking or emergency brakes of trucks and buses can be legally held on by what?

spring pressure

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

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

Some air brake systems have an alcohol evaporator. What might happen if you don't keep the unit filled with alcohol?

ice may form in the tanks and cause the brakes to fail

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

stop and park safely as soon as possible

the driver must be able to see low air pressure warning that must come on before pressure in the tanks fall below what?

60 psi

Under normal conditions, in order to engage the parking brake the driver must first:

let the air out of the system

To check the free play of manual slack adjustors on s-cam brakes, you should park on:

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

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

check and fill the alcohol level

For air brake systems in good condition, the air compressor should start pumping at what psi?

100

A straight truck or bus system should not leak at a rate of more than _ psi per minute with the engine off and the brakes released?

A slack adjustor probably needs adjustment if it moves more than _ inch when you pull on it.

If you are driving down a steep downgrade and you have reached your safe speed of 40 mph, you should apply the service brakes until your speed reaches what?

The use of brakes on a long and/or steep downgrade is only a supplement to:

the braking effect of the engine

Under ideal conditions, a truck with air brakes going 55 mph would require a stopping distance of what?

more than 300 feet

Emergency stab braking is when you:

brake as hard as you can, release the brakes when the wheels lock, and apply the brakes again when the wheels roll

The braking power of the spring brakes:

depends on the brakes being in adjustment

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

can keep your vehicle in a straight line and turn if it becomes necessary

The proper method of braking when going down hills is: to reduce your speed by mph below your safe speed before releasing the brakes?

Which of the following about ABS is true?

ABS changes the way you brake in an emergency

If your ABS is not working, you should:

drive normally, but get the system serviced soon

The stop light switch:

turns on the brake lights to warn others behind you

If air pressure does not build up to normal within the correct amount of time:

your air pressure may drop to low while driving, requiring an emergency stop

If the spring brakes are on, when should you push the brake pedal?

never

If your truck's compressor has its own oil supply, when should you first check the oil level?

before driving

The safety valve is set automatically to reduce pressure in the tanks at what psi?

150

The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than what?

3 psi in 1 minute

Air brakes take more time to stop than hydraulic brakes because:

air takes more time to flow through the lines than hydraulic fluid

In air braked vehicles, the parking brake should be used:

any time the vehicle is parked

Which of these is not the proper time to apply the parking brakes?

if the brakes are very hot

Emergency controlled braking is when you:

apply the brakes as hard as you can without locking the wheels

The application pressure gauge shows you how much pressure:

you are applying to the brakes

The supply pressure gauge shows how much pressure:

is in the air tanks

How often should you drain the water and oil from your air tanks?

at the end of each day of driving

The spring brakes on trucks will bring it to a stop automatically when air pressurt falls to what range?

20-45 psi

The air compressor should stop pumping at what psi?

125

Modern air brakes combine 3 different systems. The service, parking, and brakes.

emergency

The s-cam:

forces the brake shoes to the drums

If your truck has a dual air system, and 1 system is low on air pressure:

either the front or rear brakes will not be operating fully

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

expansion of the brake drum

If your truck has a properly functioning dual air system, the pressure should build from 85 psi to 100 psi in how long?

45 seconds

You should know that your brakes are fading when:

you have to push harder and harder on the brake pedal to control your speed

How should you check that your service brakes are working properly?

park on level ground, release the parking brakes, roll forward slowly and apply the brakes using the pedal

Total stopping distance for air brakes is longer than hydraulics because of what?

brake lag

Excessive heat caused by using your brakes too often can cause the:

brakes to fade or fail

If a truck or bus has ABS, it will have a _ malfunction lamp on the instrument panel.

yellow

The modulating control valve allow you to operate the:

spring brakes

Cracks in the drum can not be longer than _ the width of the friction area.

The air brake lag at 55 mph adds how many feet of stopping distance?

32 feet

How do you correct a rear wheel acceleration skid?

stop accelerating

Which of these systems should receive extra attention during cold weather inspections?

exhaust

Can federal inspectors inspect your truck or bus?

yes and they can put it out of service if it is unsafe

Which of these statements about tires is true?

you should inspect your tires every 2 hours or every 100 miles when driving in hot weather

If you are not sure what to use to put out hazardous materials fires, you should:

wait on qualified firefighters

When you are driving on grades, which of these is the best way to choose a safe speed?

based on your vehicle and its cargo, select a safe speed that is within the posted speed limit

When confronted by an aggressive driver, the very first thing you should do is.

make every attempt to get out of their way

general knowledge

general knowledge

general knowledge 2

general knowledge 2

combination vehicles

combination vehicles

問題一覧

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

air pressure

The brake pedal in an air brake system:

controls the air pressure applied to put on the brakes

The brake system that applies and releases the brakes when the driver uses the brake pedal is what system?

service system

All air braked equipped vehicles must have what?

a supply pressure gauge

If your truck or bus has a dual parking control valve, you can use pressure fron another tank to:

release the spring brakes to move the vehicle in an emergency

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

s-cam drum brake

Parking or emergency brakes of trucks and buses can be legally held on by what?

spring pressure

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

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

Some air brake systems have an alcohol evaporator. What might happen if you don't keep the unit filled with alcohol?

ice may form in the tanks and cause the brakes to fail

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

stop and park safely as soon as possible

the driver must be able to see low air pressure warning that must come on before pressure in the tanks fall below what?

60 psi

Under normal conditions, in order to engage the parking brake the driver must first:

let the air out of the system

To check the free play of manual slack adjustors on s-cam brakes, you should park on:

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

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

check and fill the alcohol level

For air brake systems in good condition, the air compressor should start pumping at what psi?

100

A straight truck or bus system should not leak at a rate of more than _ psi per minute with the engine off and the brakes released?

A slack adjustor probably needs adjustment if it moves more than _ inch when you pull on it.

If you are driving down a steep downgrade and you have reached your safe speed of 40 mph, you should apply the service brakes until your speed reaches what?

The use of brakes on a long and/or steep downgrade is only a supplement to:

the braking effect of the engine

Under ideal conditions, a truck with air brakes going 55 mph would require a stopping distance of what?

more than 300 feet

Emergency stab braking is when you:

brake as hard as you can, release the brakes when the wheels lock, and apply the brakes again when the wheels roll

The braking power of the spring brakes:

depends on the brakes being in adjustment

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

can keep your vehicle in a straight line and turn if it becomes necessary

The proper method of braking when going down hills is: to reduce your speed by mph below your safe speed before releasing the brakes?

Which of the following about ABS is true?

ABS changes the way you brake in an emergency

If your ABS is not working, you should:

drive normally, but get the system serviced soon

The stop light switch:

turns on the brake lights to warn others behind you

If air pressure does not build up to normal within the correct amount of time:

your air pressure may drop to low while driving, requiring an emergency stop

If the spring brakes are on, when should you push the brake pedal?

never

If your truck's compressor has its own oil supply, when should you first check the oil level?

before driving

The safety valve is set automatically to reduce pressure in the tanks at what psi?

150

The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than what?

3 psi in 1 minute

Air brakes take more time to stop than hydraulic brakes because:

air takes more time to flow through the lines than hydraulic fluid

In air braked vehicles, the parking brake should be used:

any time the vehicle is parked

Which of these is not the proper time to apply the parking brakes?

if the brakes are very hot

Emergency controlled braking is when you:

apply the brakes as hard as you can without locking the wheels

The application pressure gauge shows you how much pressure:

you are applying to the brakes

The supply pressure gauge shows how much pressure:

is in the air tanks

How often should you drain the water and oil from your air tanks?

at the end of each day of driving

The spring brakes on trucks will bring it to a stop automatically when air pressurt falls to what range?

20-45 psi

The air compressor should stop pumping at what psi?

125

Modern air brakes combine 3 different systems. The service, parking, and brakes.

emergency

The s-cam:

forces the brake shoes to the drums

If your truck has a dual air system, and 1 system is low on air pressure:

either the front or rear brakes will not be operating fully

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

expansion of the brake drum

If your truck has a properly functioning dual air system, the pressure should build from 85 psi to 100 psi in how long?

45 seconds

You should know that your brakes are fading when:

you have to push harder and harder on the brake pedal to control your speed

How should you check that your service brakes are working properly?

park on level ground, release the parking brakes, roll forward slowly and apply the brakes using the pedal

Total stopping distance for air brakes is longer than hydraulics because of what?

brake lag

Excessive heat caused by using your brakes too often can cause the:

brakes to fade or fail

If a truck or bus has ABS, it will have a _ malfunction lamp on the instrument panel.

yellow

The modulating control valve allow you to operate the:

spring brakes

Cracks in the drum can not be longer than _ the width of the friction area.

The air brake lag at 55 mph adds how many feet of stopping distance?

32 feet

How do you correct a rear wheel acceleration skid?

stop accelerating

Which of these systems should receive extra attention during cold weather inspections?

exhaust

Can federal inspectors inspect your truck or bus?

yes and they can put it out of service if it is unsafe

Which of these statements about tires is true?

you should inspect your tires every 2 hours or every 100 miles when driving in hot weather

If you are not sure what to use to put out hazardous materials fires, you should:

wait on qualified firefighters

When you are driving on grades, which of these is the best way to choose a safe speed?

based on your vehicle and its cargo, select a safe speed that is within the posted speed limit

When confronted by an aggressive driver, the very first thing you should do is.

make every attempt to get out of their way