Coupling a triple trailer is different from coupling other combinations because

you couple the third trailer to the second trailer before you couple them to the first trailer.

you couple the second trailer to the first trailer and then couple them both to the tractor.

you do not have to use a converter dolly.

The best way to stop all skids is to

use stab or controlled braking.

When uncoupling the rear semitrailer, you should lower its landing gear

enough to remove some of the trailer's weight from the converter dolly.

Which of these statements about checking your mirrors is true?

Use your mirrors to keep an eye on your tires.

Proper adjustment of your mirrors can eliminate blind spots.

You can adjust your mirrors accurately only when you're driving in traffic.

A safe speed for a single-trailer combination vehicle on a curve

may be too fast for a set of doubles or triples.

is below a safe speed for a set of doubles or triples.

is the speed at which you should drive when you're pulling doubles or triples.

During an inspection of a double or triple combination, check the usual things for any combination vehicle and also check

the shut-off valves, the converter dolly or dollies, and the air brakes on all trailers.

the fifth wheel and the landing gear.

the trailers and the radios in the tractor.

Which of the following will result in the best control on a curve?

Slow to a safe speed before entering the curve, then accelerate slightly through it.

Brake and downshift in the curve.

Slow to a safe speed before entering the curve, then coast through it.

Which of these is true?

You must drive a double or triple very smoothly to avoid a rollover or jackknife.

Empty rigs are more likely to turn over than fully loaded rigs.

When you're driving a straight truck, you need to look farther ahead than when you're pulling doubles or triples.

When driving through deep standing water, you should

apply light pressure on the brakes.

drive through as fast as possible to avoid getting your brakes wet.

pump the brake pedal to restore brake effectiveness.

Which of these statements about speed management and braking is true?

You need about four times as much braking distance at 40 mph as at 20 mph.

The stopping distance of a truck is the distance it takes to stop once the brakes are applied.

Speed limits posted on curves are safe for all trucks.

What is the definition of "off-tracking?"

How the rear wheels follow a different path from the front wheels in a turn

How the rear wheels are more likely to leave the roadside or "track"

Stopping for too long on breaks and getting "off the track" of your original schedule

Why must you inspect your double or triple combination vehicle more extensively than a vehicle with only one such semitrailer?

There are more critical parts to check.

Its design makes it more likely to have problems.

The types of cargoes it carries make it more likely to have problems.

Which of these is not a good thing to do when driving on slippery roads?

Use the engine brake or speed retarder.

Keep other traffic out of your side space.

Use a light touch on the accelerator and brake pedals.

Which of these statements about quick steering movements and doubles/triples is true?

Doubles/triples flip over from quick steering movements more easily than do many other vehicles.

You should apply the brakes at the same time that you perform quick steering movements.

Countersteering is easier with doubles/triples than with most other vehicles.

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20 questions
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Texas CDL: Double & Triple Trailers Practice Test

20 double & triple trailers questions for the Texas CDL Knowledge Test, out of 101 in the app. Answer each to see whether you got it right and why. The real Texas Double/Triple Trailers test has 20 questions and you need 16 correct (80%) to pass.

Facts updated Oct 26, 2026
Official source: law.cornell.edu
Independent, not affiliated with the DMV. How we write our questions

How it works

1Pick an answer20 questions, one tap each.
2See the ruleRight or wrong, every answer is explained.
3Get your scoreCompared with the real 80% pass mark.

Start the test

0/20 answered0 correctPass mark 80%

1Question 1 of 20
Coupling a triple trailer is different from coupling other combinations because
Not quite. The answer is you couple the third trailer to the second trailer before you couple them to the first trailer.
A triple combination vehicle has four units (not counting the converter dollies): a tractor and three trailers. You couple a triple as follows: 1. Couple the first trailer to the tractor the same way that you couple any combination vehicle. 2. Couple the third trailer to the second trailer using the method for coupling doubles (which will involve the use of a converter dolly). 3. Move another converter dolly into position. 4. Couple the tractor and first trailer to the second and third trailer using the method for coupling doubles (which will involve another converter dolly).
2Question 2 of 20
The best way to stop all skids is to
Not quite. The answer is restore traction to the tires.
If braking or steering force exceeds the tires' traction with the road surface, a skid may result. You can recover from the skid by restoring sufficient traction.
3Question 3 of 20
When uncoupling the rear semitrailer, you should lower its landing gear
Not quite. The answer is enough to remove some of the trailer's weight from the converter dolly.
Lower the landing gear of the second semitrailer enough to remove some of the trailer's weight from the converter dolly. This will make it easier to pull the dolly out from under the trailer.
4Question 4 of 20
Which of these double-trailer configurations includes just one 28.5-foot pup trailer?
Not quite. The answer is Rocky Mountain double
A double pup trailer consists of two 28.5-foot trailers, known as "pup trailers." A double pup trailer is also known as an STAA trailer, named for the Surface Transportation Assistance Act (STAA). This standard-double configuration is the only type of double trailer that is allowed nationwide. A Rocky Mountain double trailer consists of a 40- to 53-foot trailer followed by a 28.5-foot pup trailer. Rocky Mountain doubles are allowed in certain Western states. A turnpike double trailer consists of two 48-foot trailers. Turnpike doubles can be found traveling on expressways in the Eastern states.
5Question 5 of 20
The triple combination rig described in your official state CDL handbook has ____ pivot (articulation) points.
Not quite. The answer is 5
In this context, articulation or pivoting means movement between two units separated by a joint, such as between a tractor and a trailer. A triple combination has 3 semitrailers connected with 2 converter dollies. This combination has 5 points of articulation: (1) the fifth wheel of the tractor; (2) the pintle hook of the first trailer; (3) the fifth wheel of the first converter dolly; (4) the pintle hook of the second trailer; and (5) the fifth wheel of the second converter dolly.
6Question 6 of 20
Which of these statements about checking your mirrors is true?
Not quite. The answer is Use your mirrors to keep an eye on your tires.
Clean and adjust your mirrors as part of your pre-trip inspection, when your vehicle is parked. Adjust each mirror to show some part of your vehicle as well as the roadway. You can adjust your mirrors accurately only when your trailers are straight. While you're driving, use your mirrors to keep an eye on your tires. It's one way to spot a tire fire. However, no matter how carefully you adjust your mirrors, there will still be blind spots that your mirrors cannot show you.
7Question 7 of 20
A safe speed for a single-trailer combination vehicle on a curve
Not quite. The answer is may be too fast for a set of doubles or triples.
On curves, doubles and triples are more likely to roll over than other combination vehicles. A safe speed on a curve for a straight truck or a single-trailer combination vehicle may be too fast for a set of doubles or triples. To prevent trailers from rolling over, you must steer gently and go slowly around corners, on-ramps, off-ramps, and curves.
8Question 8 of 20
The crack-the-whip effect that troubles trucks with trailers is most likely to tip over
Not quite. The answer is the rear trailer of a triple.
In a double or triple combination, each trailer is more likely to roll over than the one in front of it. The rear trailer of a triple is 3.5 times as likely to roll over as a five-axle tractor-trailer. This is known as rearward amplification or the "crack-the-whip effect." For safety, position the heaviest trailer in front and the lightest trailer in the rear.
9Question 9 of 20
To uncouple the second trailer in a set of doubles, the shut-off valve at the rear of the first trailer should be
Not quite. The answer is closed.
To uncouple the second trailer, start by applying the parking brakes to keep your vehicle from moving. Lower the landing gear of the second trailer. Close the shut-off valves at the rear of the first trailer (and on the dolly if so equipped) to keep air from going out of the vehicle. Then disconnect the dolly air and electric lines, release the dolly brakes, and release the dolly fifth wheel latch. You are now ready to pull the first trailer and the dolly away from the second trailer.
10Question 10 of 20
During an inspection of a double or triple combination, check the usual things for any combination vehicle and also check
Not quite. The answer is the shut-off valves, the converter dolly or dollies, and the air brakes on all trailers.
To inspect a double or triple, first inspect it just as you would inspect any combination vehicle. Then check that the shut-off valves are open on all trailers but the last trailer. Check each converter dolly to be sure that the pintle hook is properly latched.
11Question 11 of 20
When you're coupling a set of doubles, which of the following is a way to secure the second trailer before coupling?
Not quite. The answer is Use wheel chocks.
If the second trailer doesn’t have spring brakes, drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, and disconnect the emergency line. This will set the trailer emergency brakes (assuming the slack adjusters are correctly adjusted). However, if you have any doubt about the effectiveness of the trailer's braking system, chock the wheels.
12Question 12 of 20
Which of the following will result in the best control on a curve?
Not quite. The answer is Slow to a safe speed before entering the curve, then accelerate slightly through it.
The safest way to take a curve is to slow down before the curve and then accelerate slightly through the curve. Braking in a curve risks a skid.
13Question 13 of 20
Which of these is true?
Not quite. The answer is You must drive a double or triple very smoothly to avoid a rollover or jackknife.
Take special care when pulling two or three trailers. Doubles and triples are more likely to turn over than other combination vehicles because of the "crack-the-whip" effect. You must steer gently when pulling trailers. To prevent the trailers from rolling over, you must steer gently and go slowly around corners, on-ramps, off-ramps, and curves.
14Question 14 of 20
When driving through deep standing water, you should
Not quite. The answer is apply light pressure on the brakes.
Avoid driving through deep puddles or flowing water if possible. If not, slow down and downshift into a low gear. Gently press on the brakes and maintain pressure for a short distance when you are out of the water. This will heat up the brakes and dry them out. (However, don't overdo it, or the brakes may overheat.) Then apply the brakes to make a test stop when it is safe to do so.
15Question 15 of 20
A B-double rig or B-train double rig has ____ pivot (articulation) points.
Not quite. The answer is 2
In this context, articulation or pivoting means movement between two units separated by a joint, such as between a tractor and a trailer. The standard or STAA doubles described in your official state CDL handbook are connected with an A-dolly, which has a single drawbar connected to the front trailer. However, a B-double (also called a B-train double) has a two-drawbar B-dolly (or C-dolly), which is connected to two hitches in the front trailer. The two drawbar connections prevent this type of dolly from pivoting on the front trailer. The rear trailer connects to the dolly's fifth wheel. Hence, the only two pivot points are the tractor's fifth wheel and the B-dolly's fifth wheel. B-trains are legal in parts of Michigan and Washington State.
16Question 16 of 20
Which of these statements about speed management and braking is true?
Not quite. The answer is You need about four times as much braking distance at 40 mph as at 20 mph.
Your total stopping distance is the sum of your perception distance (how far your vehicle goes from when you see the hazard until your brain processes it), reaction distance (how far the vehicle goes from when your brain orders your foot to take action until your foot actually starts to brake), and braking distance (how far the vehicle continues to travel once you apply the brake). Your vehicle's braking distance increases as the square of your speed. For example, you need about four times as much braking distance at 40 mph as you do at 20 mph.
17Question 17 of 20
What is the definition of "off-tracking?"
Not quite. The answer is How the rear wheels follow a different path from the front wheels in a turn
Off-tracking is defined as the different paths taken by the front and rear wheels in a turn. The longer the vehicle, the greater the difference will be. As a result, the path followed by a tractor will be wider than the path of the rig itself. To compensate, you must steer the tractor wider to keep the rig from overrunning the curb or hitting some object.
18Question 18 of 20
Why must you inspect your double or triple combination vehicle more extensively than a vehicle with only one such semitrailer?
Not quite. The answer is There are more critical parts to check.
There is nothing inherently wrong with double or triple trailers. There are just more critical parts to check. For a triple, you must check the critical parts of three trailers and two converter dollies, problems in any of which can cause serious trouble.
19Question 19 of 20
Which of these is not a good thing to do when driving on slippery roads?
Not quite. The answer is Use the engine brake or speed retarder.
A retarder supplements the braking force on the drive wheels. On a slippery surface, this may cause the wheels to lock, resulting in a skid. Turn off your retarder when driving on wet, icy, or snowy roads. Instead, slow down, increase your following distance, and try to brake gently.
20Question 20 of 20
Which of these statements about quick steering movements and doubles/triples is true?
Not quite. The answer is Doubles/triples flip over from quick steering movements more easily than do many other vehicles.
Because of rearward amplification (the "crack-the-whip" effect), steering changes affect the rearmost trailer much more than they affect the front trailer or the tractor. Avoid quick or sharp steering changes that could cause the rearmost trailer to roll over.

Questions people ask

Is this Texas CDL: Double & Triple Trailers Practice Test like the real Texas CDL Knowledge Test?

The questions are written in the same style as the real test, from official sources, with an explanation for each answer. The real test has 20 questions; this free test has 20.

How many questions are on the Texas CDL Knowledge Test?

The General Knowledge test has 20 questions. Each class and endorsement adds its own test.

What score do you need to pass the Texas CDL Knowledge Test?

You need 16 out of 20 correct (80%).

How old do you have to be to take the Texas CDL Knowledge Test?

You can take it from age 18.

Where can I practice more questions?

The Driving Exam Prep app has the full question bank for your test, a step-by-step roadmap, a mistakes review and a readiness score against the real pass mark.

Official sources

Our questions are written from these official sources. Always study your official handbook too: rules change, and our practice questions may differ from your real test.

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