CDL Combination
Vehicles Test

This is the Commercial Vehicle Driver's License Test covering Combination Vehicles. You will be presented with 40 questions and you must answer 34 questions correctly to pass. There is no time limit. You may not go back once you answer a question. Click the "Start Quiz" button below to begin. Good luck!

1 / 40

A trailer is at the right height to have the tractor backed up to it when:

the top of the kingpin is even with the bottom of the fifth wheel

the kingpin is about 1 1/5 inches above the fifth wheel

it'll raise slightly when the tractor is backed up under it

the fifth wheel will not come in contact with the kingpin

2 / 40

You should follow behind other vehicles ______when traveling under 40 mph.

at a distance of 1 second for every 15 feet of your vehicle length

at a distance of 1 second for every 5 feet of your vehicle length

as close as possible so other drivers won't cut in front of you

at a distance of 1 seconds for every 10 feet of your vehicle length

3 / 40

Select the true statement:

lighter vehicles requiring more braking power to stop compared to heavier vehicles

none of the answers listed

wait as long as possible to brake when driving a heavy vehicle

a "bobtail" tractor will take longer to stop than a combination vehicle that is fully loaded down to the maximum weight

4 / 40

Make sure that_____before you back under a trailer.

the air brakes are in an off position

the air supply knob has been pulled out

the air supply knob has been pushed it

the trailer brakes have been locked

5 / 40

You should expect____when backing a tractor under a trailer.

the end of the kingpin to be level with the top of the fifth wheel

the trailer to lift slightly

the trailer to be completely still

the trailer landing gear to be fully extended

6 / 40

How do you check the connection after locking the kingpin into the fifth wheel?

pull forward 25 feet, turn to the left, and then to the right

pull the tractor at a sharp right to release the trailer brakes

pull the tractor ahead gently with the trailer brakes locked down

pull forward 25 feet, turn to the right, and then to the left

7 / 40

You must first______to supply air to the trailer.

turn off the engine so you can hear the brakes

cross the air lines to check for the presence of leaks

push in the tractor protection valve

pull out the tractor protection valve

8 / 40

The purpose for the emergency air line is:

supply air to the tractor air tanks and on combination vehicles controls the emergency brakes

to supply air to the trailer air tanks and, on combination vehicles, controls the emergency brakes

none of the answers listed

supply air to the trailer air tanks and on combination vehicles, controls the service brakes

9 / 40

You should have the fifth wheel plate greased as recommened because:

it will prevent steering problems

it will ensure a good air line connection

it will ensure a good electrical connection

it will reduce noise and heat

10 / 40

How should the hand valve be used?

to test the trailer brakes

when the trailer is fully loaded down

only in conjuction with the foot brake

only in emergency situations

11 / 40

Why should you not use the trailer hand brake to straighten out a jackknifing trailer?

this is the only situation in which you should use the hand brake

the trailer wheels caused the skid in the first place once the trailer wheels grip the road again, the trailer will start to follow the tractor and straighten out

the tractor wheels caused the skid in the first place once the trailer wheels grip the road again, the trailer will start to push the tractor and straighten out

none of the answers listed

12 / 40

How high should you crank the landing gear?

until the crank handle is loose

for it to be 6 inches above the ground

as high up as it will go

so that you can clear railroad tracks

13 / 40

How do you supply air to the trailer tanks?

by pushing in the trailer air supply valve

by pulling out the trailer air supply valve

by connecting the service line glad hand

by connecting the red and blue lines

14 / 40

What should you do before you begin to couple?

position the fifth wheel beforehand

activate the spring brakes

inspect the condition of the frame of the tractor

check your path for any hazards

15 / 40

How should the trailer be lined up when preparing to back the tractor up?

directly behind the trailer

about 12 degrees to the left

about 12 degrees to the right

directly in front of the trailer

16 / 40

Select the vehicle that off-tracks the most.

a 5-axle tractor that is towing a 32-foot long trailer

a 5-axle tractor that is towing a 40-foot long trailer

a 5-axle tractor that is towing a 45-foot long trailer

a 5-axle tractor that is towing a 52-foot long trailer

17 / 40

What might happen if a trailer is too high when you try to couple?

the trailer may tip to the side

the queen pin may fall off

all answers listed

it may not correctly couple

18 / 40

Select when you should use the hand valve to park a combination vehicle.

when parking at a loading dock

never

when parking in a commercial lot

when parking on a downgrade

19 / 40

What position should the tractor protection control valve be in after coupling?

normal

lowered

raised

mid position

20 / 40

You should make sure the_____before backing under a trailer.

tractor shut off valve is normal

trailer brakes are locked down

landing gear is fully raised

air brakes have been shut off

21 / 40

What should you do if you start a trailer skid?

use your trailer hand brake

release the brakes to get traction back

quickly step on the brakes

slowly apply a firm pressure to the brakes

22 / 40

Select the answer that is controlled by the foot brake.

the shut off valves

the service air line

the emergency brake

the engine brake

23 / 40

What is the earliest way to notice a trailer skid?

you can see it in your mirrors

you can feel a jerk in the back of the tractor

you can hear the tires squealing

you can feel it pulling your steering wheel

24 / 40

When not towing a trailer, why should the tractor glad hands be locked?

the system pressure will not build up

the connected brake circuit will become a back up air tank

it keeps water and dirt out of the lines

this should never be done

25 / 40

It is good practice to_____when uncoupling.

have the glad hands coupled together

make sure the electrical cable is hanging with the plug end down

all answers are appropriate

have the glad hands coupled to the dummy couplers

26 / 40

If you park the trailer at an angle to the tractor when uncoupling:

you will have more space to maneuver in the lot

damage could occur to the landing gear

you won't have to take as many steps around the vehicle

the process will be faster and easier

27 / 40

Select the situation in which you should use the hand valve to park a combination vehicle.

in no situation

during the winter

when parking on a grade

when parking at loading docks

28 / 40

You should line up_____when getting ready to back under the trailer.

for the kingpin to activate on the driver's side first

about 12 degrees to the left of the trailer

directly in front of the trailer

above 12 degrees to the right of the trailer

29 / 40

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

there is enough clearance between the lower and upper fifth wheel

there is enough clearance between the landing gear and the tractor frame

the kingpin has been removed

the safety latch is in the open position

30 / 40

After coupling with a trailer, what position should the front trailer supports be in before driving away?

raised to the top and then taken 3 cranks down and the crank handle stored in its bracket

none of the answers listed

raised half way with the crank handle stored in the cab

in the fully raised position with the crank handle secured to its bracket

31 / 40

What should you hook up before backing a tractor to a trailer for coupling?

the electrical service line

the safety bar

there is nothing to be hooked up

the service and emergency air lines

32 / 40

Select the reason as to why you should not use the trailer hand valve while driving.

the trailer brakes will not be evenly applied

it should not be used on dry roads due to road conditions

it could cause the trailer to skid

it releases too much air from the system

33 / 40

Select the true statement in regards to crossing your air lines on a new trailer with spring brakes

you will have brakes that are not operational

there is no way to know if there is an issue

you will be unable to release the tractor brakes

you will be unable to realse the trailer brakes

34 / 40

The front trailer supports should be____before driving away.

raised fully and the crank handle secured in its bracket

3 turns down from the top and the crank handle secured in its bracket

raised 1/2 way with the crank handle secured in its bracket

raised 1/3 of the way with the crank handle secured in its bracket

35 / 40

You need to raise the landing gear just to the height of where it clears the pavement before driving.

only in ideal conditions

true

only in raining conditions

false

36 / 40

Select the true statement in regards to as why you should make sure the fifth wheel plate is greased as recommended:

to decease heat and noise

to make sure the electrical connections are good

to prevent any steering problems

to make sure that uncoupling easier

37 / 40

The trailer should be lowered so that _____.

the tractor comes in contact with the nose of the trailer

you are able to use the landing gear to make adjustments

the trailer is high above the fifth wheel

it is slightly raised when the tractor is backed under it

38 / 40

The emergency air line is _____and the service air line is____.

white, blue

yellow, white

red, blue

red, green

39 / 40

To test the tractor-trailer connection for security, you should:

rock the trailer side to side with the trailer brakes on

drive forward with a sharp jerk

drive forward in a high gear with the trailer brakes on and check it

drive forward in a low gear with the trailer brakes locked and then look at it carefully

40 / 40

When should the trailer hand valve be used?

when driving at highway speeds

when parked in a service lot

all answers listed

to test the trailer brakes

Your score is

The average score is 70%

5/5 - (3 votes)

CDL Combination Vehicles Test

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CDL Combination
Vehicles Test