combination vehicles

57問 • 2年前

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問題一覧

You supply air to the trailer tanks by:

pushing in the trailer air supply valve

Loss of air pressure in the emergency line causes:

the trailer's emergency brakes to come on

A tractor with a _ trailer requires the shortest amount of stopping distance.

fully loaded

Which of these statements is true?

bobtails tractors can take longer to stop than fully loaded combination vehicles

If you cannot make a right turn without swinging into another lane, you should:

turn wide as you complete the turn

The tractor protection valve will close and the trailer emergency brakes will come on when there is a major leak in what air line?

emergency

Off tracking or "cheating" causes which of these to follow the widest path while making a turn?

3 axle tractor towing a 45 foot trailer

If your vehicle gets stuck on a railroad crossing, you should:

get out of the vehicle and away from the tracks

When driving a set of double trailers, it is necessary to close shut-off valves on some trailers. Where are these valves located?

at the back of trailers used to tow other trailers

Before you back under a trailer, make sure of what?

the trailer brakes are locked

To unlock the fifth wheel, you pull the handle to what position?

open

After connecting the air lines but before backing under the trailer, you should:

supply air to the trailer, then pull out the trailer air supply valve

You are coupling a tractor to a semi-trailer and you have backed up but are not yet under it. What should you hook up before backing under it?

the emergency and service air

You are coupling a tractor to a trailer. The trailer is at the right height when:

the trailer is raised slightly when the tractor is backed under it

Why should you connect the air lines to a dummy coupler when they are not in use?

it will keep dirt and water out of the lines

The air leakage rate for a combination vehicle with the engine off and the brakes off should be less than _ per minute.

3 PSI

Air and electric lines from the tractor to the trailer should be:

secured properly with enough slack for turns

Air brake equipped trailers made before 1975:

often do not have spring brakes

The hand valve should be used:

to test the trailer brakes

The air leakage rate for a combination vehicle with the engine off and the brakes on should be less than _ per minute.

4 PSI

Your emergency line breaks or gets pulled apart while driving. The loss of pressure will cause the:

emergency trailer brakes to come on

You have pushed in the trailer air supply valve. You should not move the vehicle until the whole system is:

at normal pressure

When should you use the hand valve to park a combination vehicle?

never

The best way to tell that your trailer has started to skid is to:

see it in your mirrors

A trailer is most likely to jackknife when it is:

empty

If the service line comes apart but the emergency line stays together, what will happen right away?

nothing is likely to happen until you try to apply the brakes

When backing a tractor under a trailer you should:

always use the lowest reverse gear

After you have coupled the trailer, you should begin raising the landing gear using what gear?

low gear

You will know the trailer you are using has ABS by:

a yellow malfunction lamp on the left side

If you cross the air lines while coupling to an old trailer what will happen?

if the trailer has no spring brakes, you could drive away but you would not have trailer brakes

When should you get out of your vehicle when you are backing a trailer?

when you are unsure of your path of travel

When you are uncoupling a loaded trailer, you should lower the landing gear until it:

makes firm contact with the ground, then turn it a few extra cranks in low gear

How much space should be between the upper and lower fifth wheel after coupling?

none

The front trailer supports are up and the trailer is resting on the tractor. Make sure:

there is enough clearance between the frame and the landing gear

Why should you be sure that the fifth wheel is greased as required?

to prevent steering problems

After you lock the kingpin into the fifth wheel, you check the connection by:

pulling the tractor ahead gently with trailer brakes locked

After you supply air to the trailer, make sure the lines are not crossed and the brakes are working. This is done by:

applying and releasing the trailer brakes and listening for sounds

To be safe while driving, you should leave at least 1 second for every of vehicle length as following distance.

Two things you can do to prevent rolling over are keep the cargo as low to the ground as possible, and:

go slow around turns

You have a major leak in the service line and you put on the brakes. Service air pressure will escape and if it goes low enough will cause the:

trailer emergency brakes to come on

When uncoupling a trailer, after you have locked the trailer brakes, you Should:

back up gently to ease pressure on the fifth wheel jaws

When do you need to use chocks to park a trailer that does not have spring brakes?

always

The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means:

the coupling is not right and should be fixed before driving

When you get ready to back under a trailer, you should line up:

directly in front of the trailer

After you have coupled to a trailer, the tractor protection valve should be placed in the position.

normal

How should you test the trailer connection for security?

pull gently forward with the trailer brakes locked, then look at it carefully

The trailer air supply valve should automatically close when air pressure falls to what range?

20-45 PSI

What part of the kingpin should the jaws be locked around?

the shank

The higher your center of gravity of your truck, the:

easier it is to turn over

When checking that the trailer is securely coupled to the tractor, the landing gear should be:

slightly raised

If you must back your trailer on a curved path, you should position your vehicle so you can back:

to the driver's side

If your ABS is not working on your trailer, you should:

drive normally, but get the system serviced soon

Compared to a straight truck or bus, there are things to inspect on a combination vehicle.

Air lines are often colored. The emergency line is? The service line is?

red, blue

To stop a trailer skid you should?

release the service brakes

What gear should the transmission be in after you have uncoupled and are inspecting the trailer supports?

neutral

You have coupled to a trailer. Where should the landing gear be before driving away?

fully raised with the crank handle secure in the bracket

general knowledge

general knowledge

general knowledge 2

general knowledge 2

air brakes

air brakes

問題一覧

You supply air to the trailer tanks by:

pushing in the trailer air supply valve

Loss of air pressure in the emergency line causes:

the trailer's emergency brakes to come on

A tractor with a _ trailer requires the shortest amount of stopping distance.

fully loaded

Which of these statements is true?

bobtails tractors can take longer to stop than fully loaded combination vehicles

If you cannot make a right turn without swinging into another lane, you should:

turn wide as you complete the turn

The tractor protection valve will close and the trailer emergency brakes will come on when there is a major leak in what air line?

emergency

Off tracking or "cheating" causes which of these to follow the widest path while making a turn?

3 axle tractor towing a 45 foot trailer

If your vehicle gets stuck on a railroad crossing, you should:

get out of the vehicle and away from the tracks

When driving a set of double trailers, it is necessary to close shut-off valves on some trailers. Where are these valves located?

at the back of trailers used to tow other trailers

Before you back under a trailer, make sure of what?

the trailer brakes are locked

To unlock the fifth wheel, you pull the handle to what position?

open

After connecting the air lines but before backing under the trailer, you should:

supply air to the trailer, then pull out the trailer air supply valve

You are coupling a tractor to a semi-trailer and you have backed up but are not yet under it. What should you hook up before backing under it?

the emergency and service air

You are coupling a tractor to a trailer. The trailer is at the right height when:

the trailer is raised slightly when the tractor is backed under it

Why should you connect the air lines to a dummy coupler when they are not in use?

it will keep dirt and water out of the lines

The air leakage rate for a combination vehicle with the engine off and the brakes off should be less than _ per minute.

3 PSI

Air and electric lines from the tractor to the trailer should be:

secured properly with enough slack for turns

Air brake equipped trailers made before 1975:

often do not have spring brakes

The hand valve should be used:

to test the trailer brakes

The air leakage rate for a combination vehicle with the engine off and the brakes on should be less than _ per minute.

4 PSI

Your emergency line breaks or gets pulled apart while driving. The loss of pressure will cause the:

emergency trailer brakes to come on

You have pushed in the trailer air supply valve. You should not move the vehicle until the whole system is:

at normal pressure

When should you use the hand valve to park a combination vehicle?

never

The best way to tell that your trailer has started to skid is to:

see it in your mirrors

A trailer is most likely to jackknife when it is:

empty

If the service line comes apart but the emergency line stays together, what will happen right away?

nothing is likely to happen until you try to apply the brakes

When backing a tractor under a trailer you should:

always use the lowest reverse gear

After you have coupled the trailer, you should begin raising the landing gear using what gear?

low gear

You will know the trailer you are using has ABS by:

a yellow malfunction lamp on the left side

If you cross the air lines while coupling to an old trailer what will happen?

if the trailer has no spring brakes, you could drive away but you would not have trailer brakes

When should you get out of your vehicle when you are backing a trailer?

when you are unsure of your path of travel

When you are uncoupling a loaded trailer, you should lower the landing gear until it:

makes firm contact with the ground, then turn it a few extra cranks in low gear

How much space should be between the upper and lower fifth wheel after coupling?

none

The front trailer supports are up and the trailer is resting on the tractor. Make sure:

there is enough clearance between the frame and the landing gear

Why should you be sure that the fifth wheel is greased as required?

to prevent steering problems

After you lock the kingpin into the fifth wheel, you check the connection by:

pulling the tractor ahead gently with trailer brakes locked

After you supply air to the trailer, make sure the lines are not crossed and the brakes are working. This is done by:

applying and releasing the trailer brakes and listening for sounds

To be safe while driving, you should leave at least 1 second for every of vehicle length as following distance.

Two things you can do to prevent rolling over are keep the cargo as low to the ground as possible, and:

go slow around turns

You have a major leak in the service line and you put on the brakes. Service air pressure will escape and if it goes low enough will cause the:

trailer emergency brakes to come on

When uncoupling a trailer, after you have locked the trailer brakes, you Should:

back up gently to ease pressure on the fifth wheel jaws

When do you need to use chocks to park a trailer that does not have spring brakes?

always

The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means:

the coupling is not right and should be fixed before driving

When you get ready to back under a trailer, you should line up:

directly in front of the trailer

After you have coupled to a trailer, the tractor protection valve should be placed in the position.

normal

How should you test the trailer connection for security?

pull gently forward with the trailer brakes locked, then look at it carefully

The trailer air supply valve should automatically close when air pressure falls to what range?

20-45 PSI

What part of the kingpin should the jaws be locked around?

the shank

The higher your center of gravity of your truck, the:

easier it is to turn over

When checking that the trailer is securely coupled to the tractor, the landing gear should be:

slightly raised

If you must back your trailer on a curved path, you should position your vehicle so you can back:

to the driver's side

If your ABS is not working on your trailer, you should:

drive normally, but get the system serviced soon

Compared to a straight truck or bus, there are things to inspect on a combination vehicle.

Air lines are often colored. The emergency line is? The service line is?

red, blue

To stop a trailer skid you should?

release the service brakes

What gear should the transmission be in after you have uncoupled and are inspecting the trailer supports?

neutral

You have coupled to a trailer. Where should the landing gear be before driving away?

fully raised with the crank handle secure in the bracket