CDL Combination Vehicles Practice Test 2026
You take the combination vehicles test to drive a tractor-semitrailer or other Class A combination. These questions cover driving combinations safely, trailer air brakes, the coupling steps and the extra inspection checks.
Mabilis na sagot
Passing mark: 80% correct; the number of questions varies by state (20 in Washington, 30 in Utah). Pinapatakbo ito ng Your state driver licensing agency, under federal rules set by FMCSA (49 CFR Part 383). Magsanay dito nang libre gamit ang 70 tanong, bawat isa ay may sagot at paliwanag. Sinuri laban sa mga opisyal na sanggunian noong Oktubre 10, 2026.
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Tanong 1 ng 25
Ipakita ang sagot
Sagot: C. Truck rollovers
More than half of truck driver deaths in crashes are the result of truck rollovers.
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Tanong 2 ng 25
Ipakita ang sagot
Sagot: A. About 10 times more likely
Fully loaded rigs are ten times more likely to roll over in a crash than empty rigs.
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Tanong 3 ng 25
Ipakita ang sagot
Sagot: A. As low as possible, centered and spread out
Keep the center of gravity low, and keep cargo centered so the trailer does not lean.
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Tanong 4 ng 25
Ipakita ang sagot
Sagot: B. Going slowly around corners and ramps
Drive slowly in turns and on ramps, and avoid quick lane changes, especially when fully loaded.
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Tanong 5 ng 25
Ipakita ang sagot
Sagot: C. The crack-the-whip effect that can tip over a trailer
Rearward amplification makes the rear trailer swing more than the tractor in a sudden move. It can tip the trailer over.
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Tanong 6 ng 25
Ipakita ang sagot
Sagot: B. The last trailer
Because of rearward amplification, the rearmost trailer is the most likely to turn over.
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Tanong 7 ng 25
Ipakita ang sagot
Sagot: A. The rear trailer is twice as likely to tip as the tractor
A rearward amplification of 2.0 means the rear trailer is twice as likely to turn over as the tractor.
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Tanong 8 ng 25
Ipakita ang sagot
Sagot: B. Gently and smoothly
Sudden steering can tip a trailer over. Steer gently and smoothly.
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Tanong 9 ng 25
Ipakita ang sagot
Sagot: C. It may take longer to stop, as wheels lock easily
Empty rigs have stiff springs and strong brakes but poor traction, so wheels lock easily and stopping takes longer.
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Tanong 10 ng 25
Ipakita ang sagot
Sagot: D. A tractor driving without a semitrailer
A bobtail is a tractor without a trailer. It can be hard to stop smoothly and may take longer to stop than a loaded rig.
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Tanong 11 ng 25
Ipakita ang sagot
Sagot: B. Low-slung units like lowboys, car carriers and moving vans
Trailers with low underneath clearance can hang up on raised crossings.
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Tanong 12 ng 25
Ipakita ang sagot
Sagot: A. When locked trailer wheels let the trailer swing around
A trailer jackknife happens when the trailer wheels lock and the trailer swings out. It is more likely with an empty or light trailer.
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Tanong 13 ng 25
Ipakita ang sagot
Sagot: D. Check your mirrors when you brake hard
Check the mirrors any time you brake hard. Once the trailer is out of your lane, a jackknife is hard to stop.
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Tanong 14 ng 25
Ipakita ang sagot
Sagot: B. Release the brakes to get traction back
Release the brakes so the trailer wheels grip again. Do not use the trailer hand brake, because the trailer brakes caused the skid.
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Tanong 15 ng 25
Ipakita ang sagot
Sagot: D. Rear wheels taking a shorter path than the front in a turn
In turns, the rear wheels cut inside the path of the front wheels. Longer vehicles offtrack more.
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Tanong 16 ng 25
Ipakita ang sagot
Sagot: C. The rear wheels of the last trailer
The rear wheels of the rearmost trailer offtrack the most.
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Tanong 17 ng 25
Ipakita ang sagot
Sagot: D. Keep the rear near the curb, then turn wide as you finish
The button hook turn stops cars from passing you on the right. The jug-handle turn, swinging left first, is wrong.
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Tanong 18 ng 25
Ipakita ang sagot
Sagot: B. To the left
When backing a trailer, turn the wheel the opposite way from where you want the trailer to go.
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Tanong 19 ng 25
Ipakita ang sagot
Sagot: D. Turn the wheel the other way to follow it
Once the trailer starts to turn, turn the wheel the other way so the tractor follows the trailer.
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Tanong 20 ng 25
Ipakita ang sagot
Sagot: D. Toward the driver's side
Backing toward the driver's side lets you see the trailer better.
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Tanong 21 ng 25
Ipakita ang sagot
Sagot: C. Turn the top of the wheel toward the drift
Correct drift right away by turning the top of the wheel toward the drift. Back slowly so you can correct early.
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Tanong 22 ng 25
Ipakita ang sagot
Sagot: D. Pull forward (a pull-up) to reposition
Use pull-ups to get back into position when needed.
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Tanong 23 ng 25
Ipakita ang sagot
Sagot: B. At least 8 seconds
Allow 1 second per 10 feet of length (7 seconds) and add 1 second above 40 mph.
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Tanong 24 ng 25
Ipakita ang sagot
Sagot: A. Testing the trailer brakes
Use the trailer hand valve only to test the trailer brakes. Do not use it while driving or to park.
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Tanong 25 ng 25
Ipakita ang sagot
Sagot: D. The hand valve brakes only the trailer, so it may skid
Using the trailer brakes alone can make the trailer skid. The foot brake applies air to all wheels.
Keyboard: 1–4 para sumagot, Enter para sa susunod na tanong.
Ang tunay na pagsusulit: 80% correct; the number of questions varies by state (20 in Washington, 30 in Utah)
Ang dapat malaman bago ang pagsusulit
- Federal rules set the passing score for every CDL knowledge test: you must answer at least 80% of the questions correctly.
- The number of questions varies by state. Washington's combination test has 20 questions, so you need 16 correct.
- Utah's combination test has 30 questions, so at 80% you need 24 correct.
- Class A covers combinations with a gross combination weight rating of 26,001 pounds or more when the towed vehicle is rated over 10,000 pounds.
- If your Class A skills test vehicle is joined by a pintle hook instead of a fifth wheel, your CDL will be restricted from fifth-wheel tractor-trailers.
- Trailers and converter dollies built on or after March 1, 1998 must have antilock brakes, with a yellow warning lamp on the left side.
Mga madalas itanong
Who needs the combination vehicles test?
Anyone applying for a Class A CDL to drive a tractor-trailer or other heavy combination takes the combination vehicles knowledge test.
How many questions are on the combination test?
It depends on your state. Washington uses 20 questions and Utah uses 30. Either way, you need 80% to pass.
What is the most important coupling check?
Make sure there is no space between the upper and lower fifth wheel, the locking jaws are closed around the shank of the kingpin, and the locking lever is in the lock position with the safety latch over it.
What is the trailer hand valve for?
Only for testing the trailer brakes. Do not use it for normal stops or for parking.
Mga sanggunian
- Georgia DDS CDL Manual, Section 6.1: Driving Combination Vehicles Safely
- Georgia DDS CDL Manual, Section 6.2: Combination Vehicle Air Brakes
- Georgia DDS CDL Manual, Sections 6.3 and 6.4: Antilock Brakes and Coupling
- Georgia DDS CDL Manual, Sections 7.3 and 7.4: Inspecting Doubles and Triples
- Commercial Driver License Manual, Section 5: Air Brakes (Rhode Island DMV)
- 49 CFR Part 383 Subpart F: Vehicle groups and endorsements (eCFR)
- 49 CFR Part 383 Subpart H: Tests and passing scores (eCFR)
- Washington State Department of Licensing: CDL knowledge test
- Utah Driver License Division: CDL written knowledge tests