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

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

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

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

2 / 40

When you have a major leak in the service line and you apply pressure to the brakes, the service air pressure will escape and:

the trailer emergency brakes will kick on

the tractor spring brakes will kick on

the trailer tank pressure will be gone

the hand valve will stop functioning

3 / 40

You should expect____when backing a tractor under a trailer.

the trailer to lift slightly

the trailer to be completely still

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

the trailer landing gear to be fully extended

4 / 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 landing gear and the tractor frame

there is enough clearance between the lower and upper fifth wheel

the safety latch is in the open position

the kingpin has been removed

5 / 40

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

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

you will have more space to maneuver in the lot

the process will be faster and easier

damage could occur to the landing gear

6 / 40

Select the two things that are important in preventing a rollover:

the length and weight of the vehicle

drive slowly around turns and keep the cargo as close to the ground as possible

drive slowly around turns and keep the center of gravity of the cargo as high as possible

maintaining properly inflated tires and an even load on the trailer

7 / 40

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

false

only in ideal conditions

true

only in raining conditions

8 / 40

How should the hand valve be used?

only when accompanied by the service brakes

only when accompanied by the foot brake

to test the trailer brakes

only when the trailer is loaded to its maximum weight

9 / 40

Why should you use chocks when parking a trailer without spring brakes?

to prevent someone from stealing the vehicle

to prevent a runaway trailer

the trailer wheels are free to turn as there will be no service brakes should the air supply in the trailer air tank leak

the trailer wheels are free to turn as there will be no emergency brakes should the air supply in the trailer air tank leak

10 / 40

How should the hand valve be used?

only in emergency situations

only in conjuction with the foot brake

to test the trailer brakes

when the trailer is fully loaded down

11 / 40

Select the statement that best describes what the trailer air supply control does:

when pushed in it supplies the tractor with air and when pulled out it supplies the trailer with air

when pushed in it supplies the trailer with air and when you pull it out it shuts off the air supply and puts on the trailer emergency brakes

when pulled out it supplies the trailer with air and when pushed in it shuts off the air and puts on the trailer emergency brakes

when pushed it it supplies the trailer with air and when pulled out it supplies the tractor with air

12 / 40

Select the true statement in regards to large combination vehicles taking longer to stop.

they take longer to stop when they are empty

they take longer to stop than bobtail tractors

they take longer to stop when loaded down

they take the same amount of time to stop when empty or loaded

13 / 40

Select what you should not do when coupling the glad hands.

cross the air supply lines to test for leaks

clean the couplers before connecting them

make sure to match the colors or check the tags before connecting

press the seals together at a 90 degree angle

14 / 40

Make sure that_____before you back under a trailer.

the trailer brakes have been locked

the air supply knob has been pulled out

the air supply knob has been pushed it

the air brakes are in an off position

15 / 40

How high should you crank the landing gear?

so that you can clear railroad tracks

as high up as it will go

for it to be 6 inches above the ground

until the crank handle is loose

16 / 40

How do you supply air to the trailer tanks?

by connecting the red and blue lines

by pushing in the trailer air supply valve

by connecting the service line glad hand

by pulling out the trailer air supply valve

17 / 40

What will happen should a driver cross the air lines when hooking up the an older trailer?

the brake pedal will activate the trailer spring brakes instead of the air brakes

the hand valve will activate the tractor brakes instead of the trailer brakes

if there are no spring brakes, you can drive on but there will be no trailer brakes

none of the answers listed

18 / 40

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

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

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

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

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

19 / 40

The purpose for the emergency air line is:

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

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

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

none of the answers listed

20 / 40

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

red, green

yellow, white

white, blue

red, blue

21 / 40

It is good practice to_____when uncoupling.

all answers are appropriate

have the glad hands coupled together

have the glad hands coupled to the dummy couplers

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

22 / 40

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

above 12 degrees to the right of 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

23 / 40

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

it will ensure a good electrical connection

it will reduce noise and heat

it will prevent steering problems

it will ensure a good air line connection

24 / 40

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

when parking on a grade

in no situation

during the winter

when parking at loading docks

25 / 40

Select the step that comes first:

connect the air supply lines

shift into reverse

lower the landing gear

apply a firm pressure to the trailer brakes

26 / 40

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

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

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

none of the answers listed

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

27 / 40

Select the true statement:

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

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

none of the answers listed

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

28 / 40

The locking jaws of the kingpin should close around:

the shank

the base

the tip

the apex

29 / 40

Select the accurate statement in regards to rolling up the landing gear to complete the coupling process.

you should grease the landing gear the increase the speed of the process

you should use a low gear until the tractor is supporting the trailer

you should leave the landing gear at the half way mark to make the uncoupling process easier later

you should use a high gear to make the process faster

30 / 40

The front trailer supports should be____before driving away.

raised fully and the crank handle secured in its bracket

raised 1/3 of the way with 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

31 / 40

When you have a major leak in the service line and put on the brake, the service air pressure will escape and cause the:

the tractor spring brakes to activate

the trailer tank pressure to decrease

none of the ansers listed

the trailer emergency brakes to activate

32 / 40

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

the fifth wheel will not come in contact with the kingpin

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

33 / 40

You should____in order to inspect the coupling.

have the fifth wheel jaws open

make sure the locking lever is in the open position

if necessary, use a flashlight

make sure to have space between the lower and upper fifth wheel

34 / 40

The air leakage rate for combination vehicles should not be more than _ psi a minute.

35 / 40

Off-tracking happens when going around a corner and:

the rear wheels follow a different pathway than that of the front wheels

the rear part of the trailer goes into the shoulder

the rear wheels follow the front wheels in a straight path

the front part of the trailer pulls to the right

36 / 40

Is it important to look into the back of the fifth wheel to see if the lockpin is locked in?

only at the end of the shift

only every 7 days

yes

37 / 40

Select the true statement:

you should always ride the brakes

light vehicles require more braking power than heavier vehicles

wait to brake heavy vehicles for as long as you can

a bobtail tractor will take longer to stop than a combination vehicle that is loaded to the max

38 / 40

Remember to_____to prevent rollovers.

all answers listed

drive slowly around turns

have the load as low to the ground as possible

have the load centered

39 / 40

What is the service air line controlled by?

the relay vavle by sending air pressure from the trailer air tank to the trailer brake chambers

the pressure applied to the trailer hand brake or by the foot brake

all answers listed

the relay valve that connects the trailer air tanks to the trailer air brakes

40 / 40

Where should the safety catch for the fifth wheel locking lever be located for coupling to be complete?

through the locking lever

outside of the locking lever

above the locking lever

below the locking lever

Your score is

The average score is 70%

5/5 - (3 votes)

CDL Combination Vehicles Test

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CDL Combination
Vehicles Test