Combination Vehicles Flashcards

Questions and Answers

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 trailers emergency brakes to come on.

A tractor with a (n)_____ trailer requires the shortest amount of stopping distance.

fully loaded

Bobtail tractors can take longer to stop than a combination vehicle loaded to the maximum gross weight.

True Signup and view all the answers

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. Signup and view all the answers

What should you hook up before backing under a trailer?

The emergency and service air lines. Signup and view all the answers

The trailer is at the right height when:

the trailer is raised slightly when the tractor is backed under it. Signup and view all the answers

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. Signup and view all the answers

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

3 psi Signup and view all the answers

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

secured properly with enough slack for turns. Signup and view all the answers

Air brake equipped trailers made before 1975 often do not have spring brakes.

True Signup and view all the answers

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

turn wide as you complete the turn. Signup and view all the answers

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 Signup and view all the answers

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. Signup and view all the answers

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

get out of the vehicle and away from the tracks. Signup and view all the answers

Where are the shut-off valves located on some trailers that must be closed when driving a set of double trailers?

At the back of trailers used to tow other trailers. Signup and view all the answers

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

Trailer brakes are locked. Signup and view all the answers

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

to open. Signup and view all the answers

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. Signup and view all the answers

When backing a tractor under a trailer, you should:

always use the lowest reverse gear. Signup and view all the answers

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

low gear. Signup and view all the answers

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

a yellow malfunction lamp on the left side. Signup and view all the answers

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. Signup and view all the answers

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

When you are unsure of your path of travel. Signup and view all the answers

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. Signup and view all the answers

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

none. Signup and view all the answers

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. Signup and view all the answers

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

To prevent steering problems. Signup and view all the answers

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

Pulling the tractor ahead gently with the trailer brakes locked. Signup and view all the answers

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. Signup and view all the answers

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

10 Signup and view all the answers

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. Signup and view all the answers

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. Signup and view all the answers

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

back up gently to ease pressure on the fifth wheel jaws. Signup and view all the answers

You need to use chocks to park a trailer that does not have spring brakes.

False Signup and view all the answers

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. Signup and view all the answers

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

directly in front of the trailer. Signup and view all the answers

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

normal. Signup and view all the answers

How should you test the trailer connection for security?

pull gently forward with the trailer brakes locked, then look at it carefully. Signup and view all the answers

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

20-45 psi. Signup and view all the answers

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

shank. Signup and view all the answers

The higher your center of gravity of your truck, the easier it is to turn over.

True Signup and view all the answers

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

slightly raised. Signup and view all the answers

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

driver's side. Signup and view all the answers

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

drive normally, but get the system serviced soon. Signup and view all the answers

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

more. Signup and view all the answers

Air lines are often colored. Match the lines to their respective colors:

emergency line = red service line = blue Signup and view all the answers

To stop a trailer skid you should?

release the service brakes. Signup and view all the answers

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

neutral. Signup and view all the answers

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. Signup and view all the answers

The hand valve should be used:

to test the trailer brakes. Signup and view all the answers

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

4 psi. Signup and view all the answers

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

emergency trailer brakes to come on. Signup and view all the answers

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

at normal pressure. Signup and view all the answers

You should use the hand valve to park a combination vehicle.

False Signup and view all the answers

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

see it in your mirrors. Signup and view all the answers

A trailer is most likely to jackknife when it is:

empty. Signup and view all the answers

Study Notes

Air Supply and Braking Systems

Air to the trailer tanks is supplied by pushing in the trailer air supply valve.
Loss of air pressure in the emergency line engages the trailer's emergency brakes.
Air leakage should be less than 3 psi per minute with the engine off and brakes off, and less than 4 psi with the engine off and brakes on.
The tractor protection valve closes during a major leak in the emergency air line, activating trailer emergency brakes.

Coupling and Uncoupling Procedures

A fully loaded tractor-trailer combination requires the shortest stopping distance.
"Bobtail" tractors take longer to stop than fully loaded combination vehicles.
Ensure trailer brakes are locked before backing under the trailer.
Prior to coupling, the emergency and service air lines should be hooked up while not yet under the trailer.
After coupling, raise the landing gear using low gear until firmly in contact with the ground.

Trailer Visibility and Handling

Off-tracking or "cheating" refers to a wide path taken by a 3 axle tractor towing a 45-foot trailer during turns.
When turning right, if the vehicle could swing into another lane, make a wider turn to avoid conflict.
Use chocks to park trailers without spring brakes to prevent movement.

Safety and Maintenance Checks

Check the fifth wheel is greased adequately to avoid steering difficulties.
Verify the trailer is securely attached by gently pulling forward while trailer brakes are locked.
The fifth wheel locking lever must be properly locked around the kingpin to ensure secure coupling.
Look for a yellow malfunction lamp on the left side to confirm if the trailer has ABS.

Emergency and Performance Protocols

If unable to make a right turn without encroaching into another lane, opt for a wider turn arc.
In case of vehicle being stuck on railroad tracks, exit immediately and move away from the tracks for safety.
The transmission should be in neutral when inspecting trailer supports after uncoupling.
Anticipate an empty trailer is more likely to jackknife during sharp turns.

Other Important Facts

Release the service brakes to stop a trailer skid and avoid engaging the hand valve for parking.
When backing, align directly in front of the trailer for better control.
Secure air and electric lines properly while allowing enough slack for turns.
Ensure clearances are maintained between the trailer frame and landing gear when lifted.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge of combination vehicles with these flashcards. Each card focuses on crucial concepts such as air supply, emergency brakes, and stopping distances. Perfect for anyone preparing for a commercial driver's license.

Combination Vehicles Flashcards

Questions and Answers

You supply air to the trailer tanks by:

Loss of air pressure in the emergency line causes:

A tractor with a (n)_____ trailer requires the shortest amount of stopping distance.

Bobtail tractors can take longer to stop than a combination vehicle loaded to the maximum gross weight.

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

What should you hook up before backing under a trailer?

The trailer is at the right height when:

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

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

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

Air brake equipped trailers made before 1975 often do not have spring brakes.

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

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

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

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

Where are the shut-off valves located on some trailers that must be closed when driving a set of double trailers?

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

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

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

When backing a tractor under a trailer, you should:

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

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

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

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

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

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

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

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

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

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

To be safe while driving, you should leave at least 1 second for every_____feet 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:

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:

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

You need to use chocks to park a trailer that does not have spring brakes.

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

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

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

How should you test the trailer connection for security?

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

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

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:

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

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

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

Air lines are often colored. Match the lines to their respective colors:

To stop a trailer skid you should?

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

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

The hand valve should be used:

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

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

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

You should use the hand valve to park a combination vehicle.

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

A trailer is most likely to jackknife when it is:

Study Notes

Air Supply and Braking Systems

Coupling and Uncoupling Procedures

Trailer Visibility and Handling

Safety and Maintenance Checks

Emergency and Performance Protocols

Other Important Facts

Studying That Suits You

Description

More Quizzes Like This

North American Combination Vehicles Quiz

CDL Combination Flashcards

Combination Vehicle CDL Flashcards

Combination Circuits Flashcards