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 driving a truck with triple or double trailers:

the risk of trailer jackknifes and tipping is increased compared to shorter trucks

the truck requires increased following distance compared to smaller vehicles

all answers listed

extra care should be taken when driving in bad weather and in the mountains

2 / 40

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

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

visually check that they are level height wise

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

you do not need to do a visual check

3 / 40

Start by___when coupling.

having the second trailer against the dock

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

backing the converter dolly under the second trailer

coupling the tractor to the second trailer

4 / 40

In what position should the converter dolly air tank drain valve be in for double trailer combination?

in a halfway closed position

in a 1/3 open position

in a closed position

in an open position

5 / 40

Select the true statement about handling triples and doubles:

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

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

triples and doubles handle the same as singles

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

6 / 40

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

by opening the air tank petcock

by opening the shut off valve

by flushing the brake line

by charging the air line

7 / 40

How do you hook a combination to a second trailer without spring brakes and without using wheel chocks?

have the trailer electric cord to a generator so it can supply braking power

make sure th trailer won't roll when coupling

disconnect the air supply lines after supplying air to the trailer air system via the tractor

go ahead and couple it

8 / 40

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

when the tractor brakes lock up

when the trailer slides to the right into the shoulder

when the tractor spins around

when the trailer pushes the towed vehicle sideways

9 / 40

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

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

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

none of the answers listed

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

10 / 40

Select the true statement in regards to handing triples and doubles

none of the answers listed

due to the crack the whip effect, the rear trailer of a 100 foot triple is less likely to tip than a single trailer

due to off tracking, a triple bottom rig can come to a stop quicker than a 5 axle semi trailer

a sudden movement of the steering wheel may result in the rear trailer tipping over

11 / 40

Do converter dollies have spring brakes?

some do

none of the answers listed

yes

12 / 40

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

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

only a certified mechanic can check for this

pump the brakes with the windows down

check the pressure indicator dial on the final trailer

13 / 40

In what position should the converter dolly air tank drain valves and pintle hook be in?

open and latched

closed and open

open and open

closed and latched

14 / 40

You should keep a minimum of ____between another vehicle and the double trailer with 100 ft truck driving at 30 mph.

15 seconds

10 seconds

8 seconds

13 seconds

15 / 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?

6 seconds

8 seconds

11 seconds

13 seconds

16 / 40

The driver's manual advises you to disconnect the steering axle brake to keep the rig straight:

in ideal conditions

when it is raining

never

whever you feel like it

17 / 40

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

watch the brake lights as you step on the brake pedal

pull the vehicle forward and then step on the brakes

listen for escaping air after opening the emergency shut off valve

while on an level surface, test the emergency brake lines

18 / 40

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

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

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

the kingpin is resting behind the fifth wheel

the top of the kingpin lines up with the locking jaws

19 / 40

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

the rig will slide sideways but stay in a straight line

nothing will occur

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

there will be a trailer jackknife

20 / 40

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

1 to 2 inches

zero

it is dependent on the load you are carrying

1/4 to 1/2 of an inch

21 / 40

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

false

only in ideal conditions

only on downgrades

true

22 / 40

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

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

close the shut off valves at the back of each trailer

open the shut off valve at the back of both trailers

none of the answers listed

23 / 40

For emergency braking when driving a double trailer and having to use your brakes to avoid a collision is to:

apply a firm pressure to the brake pedal and don’t let off

use stab or controlled braking

use just the trailer brakes

use the engine brake

24 / 40

Why should you test the tractor protection valve?

to avoid the emergency brakes kicking on due to loss of air

to avoid loss of air from the trailer brakes

all answers listed

to avoid loss of air from the air hose

25 / 40

What is the best way to prevent brakes form overheating while drive down a steep grade?

use countersteering practices

use the stab braking method

use the trailer brakes only

drive at a speed of 5 mph below your safe speed

26 / 40

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

drive with extra care in mountains and in bad weather

none of the answers listed

increase your following distance

all of the answers listed

27 / 40

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

the air lines will explode

the dolly tow bar could fly up

nothing will happen

the engine brakes will unlock

28 / 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 front trailer

open at the rear of the last trailer and front trailer

none of the answers listed

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

29 / 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?

none of the answers listed

use a portable generator to supply brake pressure

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

30 / 40

What should you check for when inspecting a converter dolly?

that the safety chains are secured to the trailer

that the spare tire is secured if there is one

that the converter dolly air tank drain valve is in the closed position

all answers listed

31 / 40

You should check your mirrors while making a lane change:

right after you start the lane change

after you have completed the lane change

after you signal your intent to change lanes

all answers listed

32 / 40

Which trailer should be the first one after the tractor?

the trailer that weighs the least

the trailer that is the shortest in length

none of the answers listed

the trailer that weighs the most

33 / 40

Why is it dangerous to unlock the pintle hook with the dolly still under the rear trailer?

the dolly tow bar may fly up

the spring brakes may release

the kingpin may snap in half

the fifth wheel may be misaligned

34 / 40

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

any trailer

a fully loaded trailer behind the tractor

the last trailer of a double

the last trailer of a triple

35 / 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

36 / 40

The best way to have control on curves is:

to shift to a lower gear before entering the curve

to decrease to your safe speed before entering the curve and then accelerate through it

you do not need to do anything different

keep pressure on the brake pedal through the turn

37 / 40

Select the statement that is true in regards to managing space to the sides.

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

you should try to avoid driving next to others when possible

all answers listed

high gust winds do not cause any issues for triples and doubles

38 / 40

The correct trailer height when coupling the rear trailer is:

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

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

39 / 40

Select the true statement in regards to converter dollies:

they typically do not have spring brakes

they typically have small braking power because of their size

they typically have a lot of stopping power because of their size

they typically require a hand converter

40 / 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

only at the end of a shift

true

Your score is

The average score is 0%

4/5 - (2 votes)

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