CDL Double-Triple
Trailers Test

This is the Commercial Vehicle Driver's License Test covering Double and Triple Trailers. 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

Select the true statement in regards to a converter dolly:

it is a coupling device with one or two axles and a fifth wheel with which a semitrailer can be coupled to the rear of a tractor-trailer combination forming a double bottom rig

it is a coupling device with only two axles and a sixth wheel to which a semitrailer can be coupled to the rear of a tractor-trailer combination forming a double bottom rig

it is a connecting device consisting of one axle which disconnects a semitrailer combination vehicle converting it into two separate trailers

none of the answers listed

2 / 40

What is the stopping distance for a tractor trailer that is traveling at 55 mph on dry pavement?

about 600 feet with is about two football field lengths

about 200 feet which is 2/3 of a football field

about 150 feet which is 1/2 of a football field

about 300 feet which is about a football field length

3 / 40

Mirrors with a convex surface or "spot" mirrors _____.

make things look farther away and smaller than they actually are

they show a larger area than flat mirrors so do not need to be checked as often

make things look closer and larger than they actually are

are illegal in most states

4 / 40

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

zero

it is dependent on the load you are carrying

1/4 to 1/2 of an inch

1 to 2 inches

5 / 40

What should you hear when you test the trailer brakes by opening the service air line at rear of trailer with the hand valve on?

the service brakes will move to a fully applied position

you should hear air escape from the open valve

the emergency air line will release air

none of the answers listed

6 / 40

Start by___when coupling.

coupling the converter hook to the pintle tongue of the first trailer

coupling the tractor to the second trailer

having the second trailer against the dock

backing the converter dolly under the second trailer

7 / 40

Remember to_____when steering to avoid a crash while driving doubles.

have both hands on the steering wheel

be prepared to counter-steer

all answers listed

keep your foot off the brake while turning

8 / 40

The trailer height is correct for connecting a converter dolly to a second or third trailer when:

all answers listed

the kingpin is over the fifth wheel

the trailer will rise slightly when the converter dolly is backed underneath it

the center of the kingpin is past the locking jaw

9 / 40

Select the statement that is true in regards to what is required of a driver with a double or triple trailers:

none of the answers listed

drive with extra care in mountains and in bad weather

all of the answers listed

increase your following distance

10 / 40

The correct trailer height when coupling the rear trailer is:

there is 5 inches of space between the lower and upper fifth wheel

when the locking jaws are open around the kingpin

the kingpin is touching the fifth wheel

slightly lower than the center of the fifth wheel

11 / 40

To be sure that air is supplied to the second trailer:

open the emergency line shut off at the back of the second trailer

crank the engine brake

keep an eye of the air gauge for a drop of 30 psi

while driving at 10 mph, use the hand valve. The vehicle should stop in the same distance of a single trailer moving at 5 mph

12 / 40

What is most likely to occur when driving a set of doubles and a set of trailer wheels goes into a skid?

no matter how you turn the steering wheel, the rig will continue in a straight line

nothing will occur

the rig will slide sideways but stay in a straight line

there will be a trailer jackknife

13 / 40

The trailer height is correct for connecting a converter dolly to a second trailer when:

the trailer will slightly rise when the converter dolly is backed under it

the top of the kingpin lines up with the locking jaws

the kingpin is resting behind the fifth wheel

the trailer will slightly lower when the converter dolly backed under it

14 / 40

When would a drive-wheel skid result in a jackknife when pulling doubles?

when the trailer pushes the towed vehicle sideways

when the tractor brakes lock up

when the tractor spins around

when the trailer slides to the right into the shoulder

15 / 40

Do converter dollies have spring brakes?

some do

yes

none of the answers listed

16 / 40

Which trailer is more likely to roll over when pulling 3 trailers?

the second trailer

the last trailer

the tractor

the first trailer

17 / 40

Select the action that is not recommended when driving on slipper roads:

use a light pressure with the the brake and accelerator pedals

use a speed retarder or engine brake

keep other drivers out of your side space

none of the answers listed

18 / 40

How do you check the air flow to the last trailer?

watch the brake lights as you step on the brake pedal

listen for escaping air after opening the emergency shut off valve

while on an level surface, test the emergency brake lines

pull the vehicle forward and then step on the brakes

19 / 40

Select the true statement about double or triple trailers.

all answers listed

they can have a dangerous "crack the whip" effect

they can roll over duee to abrupt steering movements

they present a rearward amplification hazard

20 / 40

You don't want to use wheel chocks when hooking a combination to a second trailer with no spring brakes. What should you do?

use a portable generator to supply brake pressure

none of the answers listed

make sure the trailer will not roll away when coupling

supply air to the trailer air system via the tractor and then disconnect the emergency line

21 / 40

How should the shut off valves at the rear of the trailer be when inspecting doubles?

closed at the rear of the last trailer and open at the rear of the front trailer

closed at the rear of the last trailer and front trailer

open at the rear of the last trailer and front trailer

none of the answers listed

22 / 40

Double and triple trailers should be driven with care to avoid a rollover or jacknife.

only on downgrades

only in ideal conditions

true

false

23 / 40

What position should the heaviest trailer be in when pulling 3 trailers?

in the front

in the middle

in the back

it makes no difference

24 / 40

Select the true statement about handling triples and doubles:

because of the crack the whip effect, the rear trailer of a 100-foot triple is less likely to tip over

due to off-tracking, a triple bottom rig can come to a stop faster than a 5-axle tractor

triples and doubles handle the same as singles

a tip over of the rear trailer can occur due to sudden movements of the steering wheel

25 / 40

You should_____to uncouple the converter dolly.

chock the wheels, lower the landing gear, and disconnect the safey chains

chock the wheels, disconnect the safety chains, and then lower the landing gear

disconnect the safey chains, lower the landing gear, and chock the wheels

lower the landing gear, disconnect the safety chain, and chock the wheels

26 / 40

Select the true statement about convex ("spot") mirrors.

they are against the law in the majority of states

they make things closer and larger than they really are

you do not need to look at them as often as flat mirrors

they make things look farther away and smaller than they actually are

27 / 40

How do you make sure the trailer height is correct before coupling?

visually check that they are level height wise

you do not need to do a visual check

visually check that the lead trailer is higher than the fifth wheel so that the trailer will lower when the dolly is pushed under it

visually check that the rear trailer is lower than the fifth wheel so that the trailer raises slightly when the dolly is pushed under it

28 / 40

What is the minimum amount of distance you should maintain when driving at 50 mph in ideal conditions with a 100 ft twin trailer combination?

13 seconds

8 seconds

11 seconds

6 seconds

29 / 40

What do you need to do to supply air to the air tranks of the second trailer?

close the shut off valves at the back of each trailer

none of the answers listed

open up the shutt off valves on the rear of the first trailer and close the shut off valve at the back of the second trailer

open the shut off valve at the back of both trailers

30 / 40

What do you check when doing a visual inspection of the coupling?

that the locking jaw is closed around the kingpin and that there is no space between the upper and lower fifth wheel

none of the answers listed

the locking jaw is closed around the kingpin and there is no space beween the lower and upper fifth wheel

that the locking jaw is open around the kingpin and that there is some space between the lower and upper fifth wheel

31 / 40

Select the true statement in regards to managing the space to the sides:

you should always keep your vehicle to the right side of the lane

you should drive down the center of both lanes over the pavement markings

high wind gusts will not cause any issues for doubles or triples

you should try to avoid driving next to others when possible

32 / 40

What is most likely to occur when driving double and a set of trailer wheels goes into a skid?

the rig will continue straight ahead but will slide sideways

none of the answers listed

the tractor will continue moving in a straight line no matter how you turn the steering wheel

the trailer will jackknife

33 / 40

Which trailer should be the first one after the tractor?

the trailer that is the shortest in length

none of the answers listed

the trailer that weighs the least

the trailer that weighs the most

34 / 40

What method should be used to test that the air is flowing to all the trailers?

check the pressure indicator dial on the final trailer

only a certified mechanic can check for this

pump the brakes with the windows down

listen for air flow after opening the shutoff valves at the rear of the last trailer

35 / 40

When driving with multiple trailers, which one should be right behind the tractor?

the trailers shortest in length

the trailer with the smallest road

the trailer longest in length

the trailer with the heaviest load

36 / 40

How do you release the dolly brakes when coupling twin trailers?

by opening the shut off valve

by flushing the brake line

by charging the air line

by opening the air tank petcock

37 / 40

You should look into the back of the fifth wheel on a dolly to see if it is locked onto the kingpin.

only in a level loading dock

false

true

only at the end of a shift

38 / 40

What should you hear when you have the hand valve on and are testing the trailer brakes by opening the service air line at the back of the trailer?

the engine brake to kick on

the emergency line valve to release air

air leaving the open valve

the service brakes more to a fully applied position

39 / 40

Which is more likely to tip over due to the crack the whip effect?

any trailer

the last trailer of a double

a fully loaded trailer behind the tractor

the last trailer of a triple

40 / 40

What will probably happen if the converter dolly is still under the second trailer and the pintle hook is unhooked?

nothing will happen

the air lines will explode

the engine brakes will unlock

the dolly tow bar could fly up

Your score is

The average score is 0%

4/5 - (2 votes)

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