Connecticut Combination Vehicles CDL Practice Test

This is a free 20-question practice test for the Combination Vehicles portion of the Connecticut Commercial Driver's License knowledge exam. Questions are pulled from a pool of 55 drawn from the AAMVA CDL Manual, which is the source document the Connecticut Department of Motor Vehicles uses to write its actual exam.

How it works: Click an answer. The correct choice highlights in green, and you'll see a short explanation. Aim for 85% or better before you sit for the real test in Connecticut.

Question 1 of 20

On a tight curve or exit ramp, a tractor-trailer is most likely to roll over because:

The trailer brakes lock
The high center of gravity creates a tipping force greater than the tires can resist
The tractor accelerates
The road is dry

Correct. Centripetal forces in a curve push the cargo outward; a high center of gravity multiplies the tipping moment. Slow before the curve.

Question 2 of 20

Combination vehicles are usually:

Easier to drive than single trucks
Harder to drive than single trucks because of length, weight, and the unique handling of articulated vehicles
The same as single trucks
Faster than single trucks

Correct. Combination vehicles (tractor-trailer rigs) are heavier, longer, and articulate at the fifth wheel — all making them more demanding than single-unit trucks.

Question 3 of 20

When you couple, the locking jaws of the fifth wheel must close around:

The kingpin shank, not just the head
Just the head
The trailer skirt
The wheel

Correct. The locking jaws must engage the kingpin shank below the head. If the jaws close above the head, the connection is unsafe.

Question 4 of 20

When you supply air to the trailer for the first time after coupling, you should:

Wait until air pressure builds in the trailer reservoir, then test the trailer brakes by pulling out the trailer-supply knob
Drive away immediately
Disconnect the lines
Skip the test

Correct. Charge the trailer system. Then test the trailer brake function by tugging gently or pulling the trailer-supply knob to confirm trailer brakes apply.

Question 5 of 20

Auxiliary equipment (refrigeration, hydraulic lift gates) on the trailer:

Has no effect on the rig
Adds weight and may change rear-axle loading; verify securement and operation
Replaces the brakes
Cannot be operated while loaded

Correct. Reefer units, lift gates, and other auxiliary equipment add weight and may shift CG. Inspect securement and check operation in pre-trip.

Question 6 of 20

The "rearward amplification" effect:

Is greatest in the lead trailer
Is greatest in the rear-most trailer of doubles or triples
Does not exist
Is the same in every trailer

Correct. Rearward amplification — the crack-the-whip effect — is most severe in the rear trailer of a multi-trailer combination.

Question 7 of 20

When making a U-turn, a tractor-trailer needs:

Less space than a car
Substantially more space than a car — often more than a single intersection allows
The same space as a car
No turning space

Correct. Tractor-trailer turning radius is much larger than a car. A standard intersection rarely allows a U-turn — find a wider turning area.

Question 8 of 20

Maximum allowable trailer-brake leakage rate (engine off, brakes released, combination vehicle) is:

1 psi/min
3 psi/min
5 psi/min
7 psi/min

Correct. Combination vehicles: no more than 3 psi/min with brakes released, 4 psi/min with brakes applied.

Question 9 of 20

During a pre-trip inspection, you should also check that the cargo:

Is loaded inside the vehicle
Is secured, balanced, within weight limits, and within size limits
Is brightly colored
Is all the same shape

Correct. Cargo securement, weight balance, and size compliance are all driver responsibilities — check before each trip.

Question 10 of 20

When you are backing a trailer to the right, you should turn the steering wheel:

Left to start the trailer right
Right to start the trailer right
In the same direction every time
Never use the steering wheel; just push

Correct. When backing, the trailer goes opposite to the way you initially turn the steering wheel. To make the trailer go right (passenger side), start by turning the wheel left.

Question 11 of 20

Front-trailer (lead) wheels lock and the trailer behind continues forward — this is:

Trailer jackknife
Tractor jackknife
Tire blowout
Off-tracking

Correct. When the trailer wheels lose traction and the front-of-trailer pivots while the tractor continues forward, the result is a trailer jackknife.

Question 12 of 20

When you cross railroad tracks in a tractor-trailer, you should:

Shift gears to maintain speed
Cross in a single gear without shifting, and never start across without room to clear the rails
Stop on the tracks if the light turns red
Honk repeatedly

Correct. Crossing in one gear (without shifting) prevents stalling on the tracks. Never enter a crossing unless you can clear it without stopping.

Question 13 of 20

When you check the fifth wheel during pre-trip, you look for:

Mounting to the frame is secure, no missing or damaged parts, no visible space between the upper and lower fifth-wheel plates, locking jaws around the kingpin shank, release arm in the locked position
Only the color
Only the bolts
Only the grease

Correct. Check mount, condition, gap, jaw engagement around kingpin shank (not the head), and release-arm lock position. Lubrication should be present but not excessive.

Question 14 of 20

When approaching a curve in a tractor-trailer, you should:

Brake during the curve
Slow down before entering the curve
Speed up
Maintain steady speed

Correct. Slow before entering the curve. Once in the curve, accelerate gently to maintain stability. Braking in a curve invites trailer skid or rollover.

Question 15 of 20

When you connect the glad-hands, you should:

Cross-connect the red and blue lines so they cannot be confused
Connect both to the same color glad-hand
Pinch the seal first
Push them in straight without rotating

Correct. Push the glad-hands together so the rubber seals match, then rotate to lock. Be sure red goes to red and blue goes to blue (the lines themselves often cross to keep colors matched).

Question 16 of 20

Before uncoupling, you should:

Park on level ground, set the trailer parking brake, lower the landing gear, disconnect air and electrical lines, then release the fifth-wheel jaws
Just pull away
Disconnect electrical only
Drive forward fast

Correct. Proper sequence: park level, lower landing gear to support the trailer, disconnect lines, release jaws, then pull forward slowly. Skipping any step risks dropping the trailer.

Question 17 of 20

When making a turn, you should signal:

Just before the turn
Well in advance — at least 100 feet for a turn at low speed
Only if other vehicles are present
At the start of the turn

Correct. Signal early enough that other drivers see and process the signal — generally at least 100 feet before in town, longer at highway speeds.

Question 18 of 20

To make a trailer go where you want when backing, the steering wheel should:

Be turned in the direction you want the trailer to go
Be turned opposite to the direction you want the trailer to go (then corrected)
Stay still
Be held lightly

Correct. Backing is opposite-direction steering: to swing the trailer right, turn the wheel left first, then correct as the trailer follows.

Question 19 of 20

When inspecting the kingpin during pre-trip, look for:

Excessive wear, bending, cracks, or improper lock-jaw engagement
Only the color
Only the size
Only the grease

Correct. A worn, cracked, or bent kingpin can fail under load. The locking jaws must close completely around the shank, not just the head.

Question 20 of 20

A combination-vehicle pre-trip should include:

All single-vehicle items plus fifth wheel, kingpin, sliding fifth wheel/sliding tandem locks, mud flaps, trailer brakes, lights, and trailer tires
Only the tractor
Only the trailer
Only the cargo

Correct. You inspect the entire rig — tractor + trailer + connections + cargo securement — not just the tractor.

About the Connecticut Combination Vehicles exam

Most states administer 20 Combination Vehicles questions and require 80% to pass. The exam emphasizes the unique handling of articulated vehicles: how trailers track behind the tractor, how to prevent rollover, how to manage rearward amplification with multi-trailer combinations, and the correct sequence to couple and uncouple.

The Connecticut Department of Motor Vehicles follows the federal CDL standards established by FMCSA. To earn the Combination Vehicles credential, you must answer at least 80% of the questions correctly. Many candidates score lower the first time because the test pulls from a large pool — refreshing this page will give you a different mix of questions, drawn from the same authoritative source.

Want more practice? Try the full Combination Vehicles question bank or browse all Connecticut CDL practice tests.