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

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

the trailer with the heaviest load

the trailer with the smallest road

the trailer longest in length

the trailers shortest in length

2 / 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 service brakes more to a fully applied position

air leaving the open valve

the emergency line valve to release air

3 / 40

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

open at the rear of the last trailer and front trailer

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

none of the answers listed

closed at the rear of the last trailer and front trailer

4 / 40

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

the last trailer

the first trailer

the second trailer

the tractor

5 / 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

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

crank the engine brake

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

6 / 40

Remember to_____when steering to avoid a crash while driving doubles.

be prepared to counter-steer

have both hands on the steering wheel

keep your foot off the brake while turning

all answers listed

7 / 40

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

open the shut off valve at the back of both trailers

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

none of the answers listed

8 / 40

The pintle hook should be_____ and the converter dolly air tank drain valve is___when doing a walk around inspection of a triple or double trailer.

free, closed

latched, open

free, open

latched, closed

9 / 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

10 / 40

In what position should shut off valves on the rear of the last trailer be in on a set of double trailers?

in a closed position for the rear trailer and open position for the front trailers

in a open position for the rear trailer and a closed position for the front trailer

in a closed position

in a open position

11 / 40

In what position should the shut off valves on a the rear of the front trailer be in on a set of double trailers?

in a 1/3 way open position

in an open position

in a halfway open position

in a closed position

12 / 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 center of the kingpin is past the locking jaw

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

13 / 40

Select the true statement about double or triple trailers.

they can have a dangerous "crack the whip" effect

they can roll over duee to abrupt steering movements

all answers listed

they present a rearward amplification hazard

14 / 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?

11 seconds

6 seconds

8 seconds

13 seconds

15 / 40

Select the true statement in regards to quick steering movements and double trailers:

you should apply a firm pressure to the brake pedal at the same moment you do quick steering movements

nothing will occur

it is easier to countersteer doubles/triples than other vehicles

it is easier to tip doubles and triples from quick steering movements than other vehicles

16 / 40

For emergency braking to avoid a crash when driving a double trailer you should:

none of the answers listed

slam down the brake pedal and keep pressure on it

do stab or controlled braking

use the trailer brakes only

17 / 40

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

the last trailer of a double

any trailer

a fully loaded trailer behind the tractor

the last trailer of a triple

18 / 40

Select the true statement about converter dollies:

all answers listed

they usually do not have spring brakes

they typically require a glad hand converter

because of their small size they have little braking power

19 / 40

Select the true statement in regards to a converter dolly:

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

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

20 / 40

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

none of the answers listed

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

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

21 / 40

You should check your mirrors while making a lane change:

after you signal your intent to change lanes

all answers listed

after you have completed the lane change

right after you start the lane change

22 / 40

You should_____to uncouple the converter dolly.

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

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

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

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

23 / 40

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

in an open position

in a 1/3 open position

in a closed position

in a halfway closed position

24 / 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

25 / 40

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

there will be a trailer jackknife

the rig will slide sideways but stay in a straight line

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

nothing will occur

26 / 40

What do yo uneed to do before supplying air to the air tanks of the second trailer?

open the shut off valves at the back of the first and second trailer

close the shut off valves at the back of the second trailer and open the shut off valves at the back of the first trailer

open the shut off vavles at the back of the second trailer and close the shut off valves at the back of the first trailer

close the shut off valves at the back of the first and second trailer

27 / 40

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

make things look farther away and smaller than they actually are

make things look closer and larger than they actually are

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

are illegal in most states

28 / 40

The best way to have control on curves is:

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

you do not need to do anything different

to shift to a lower gear before entering the curve

keep pressure on the brake pedal through the turn

29 / 40

What is the best way to stop all skids?

restore traction back to the tires

quickly turn the steering wheel side to side

accelerate and countersteer

use controlled or stab braking

30 / 40

The main reason you should pull the dolly out from under a trailer before disconnecting it from the trailer in front is:

removing the dolly before uncoupling is not the correct procedure

so the rear-trailer's air brake system will stay charged and keep the trailer wheels locked to prevent rolling

it is possible that the dolly tow bar could fly up making it difficult to re-couple

to provide additional lateral stabilization to the front trailer

31 / 40

How should you inspect a converter dolly?

as if it is an axle with a fifth wheel

as if it is an engine

as if it is a trailer

as if it is cargo

32 / 40

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

true

only in a level loading dock

only at the end of a shift

false

33 / 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?

none of the answers listed

you should hear air escape from the open valve

the emergency air line will release air

the service brakes will move to a fully applied position

34 / 40

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

closed and open

open and open

closed and latched

open and latched

35 / 40

Select the true statement about empty trucks:

they have a smaller stopping distance than full trailers

empty trucks stop in the same distance as a fully loaded truck

they have poor traction due to wheel lockup and bouncing

empty trailers are easier to stop because there is not cargo shifting

36 / 40

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

the first trailer of a triples

the last trailer of a triple

the last trailer of a double

the heaviest trailer

37 / 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

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

the trailer will jackknife

none of the answers listed

38 / 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

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

triples and doubles handle the same as singles

39 / 40

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

it is dependent on the load you are carrying

1/4 to 1/2 of an inch

zero

1 to 2 inches

40 / 40

Select the statement that is true in regards to quick steering movements and triple/double trailers:

they flip over due to quick steering movements a lot easier than other vehicles

it is easier to countersteer compared to other vehicles

as you perform quick steering movements you should apply pressure to the brake pedal

CDL Double-Triple
Trailers Test

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CDL Double-Triple Trailers Test

CDL Category Practice Tests

CDL General Knowledge Test

Combination Vehicles Test

Passenger Vehicles Test

Pre-Trip Inspections Test

Double/Triple Trailers

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CDL Air Brakes Test

Hazardous Materials Test

CDL Tanker Vehicles Test

CDL Double-Triple
Trailers Test