New Hampshire Doubles/Triples CDL Practice Test

This is a free 20-question practice test for the Doubles/Triples portion of the New Hampshire Commercial Driver's License knowledge exam. Questions are pulled from a pool of 50 drawn from the AAMVA CDL Manual, which is the source document the New Hampshire Division 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 New Hampshire.

Question 1 of 20

Before connecting a converter dolly, you should:

Inspect tires, brakes, fifth-wheel jaws, and overall condition
Skip inspection
Only check the tires
Only check the lights

Correct. Pre-trip the dolly: tires, brake adjustment, fifth-wheel jaws (open and clean), pintle hook, electrical receptacle, lights.

Question 2 of 20

Drivers should always couple the heaviest trailer:

Behind the tractor (in the front position)
At the rear
In the middle
It does not matter

Correct. Heaviest trailer goes directly behind the tractor; lightest goes at the rear. This minimizes rearward amplification and rollover risk.

Question 3 of 20

During a pre-trip on doubles, the trailer-supply line:

Should be open from tractor to rear-most trailer
Should be open at the front but closed at the rear-most trailer
Should be closed everywhere
Should always be disconnected

Correct. The supply line carries air from tractor through every trailer; verify open valves at every coupled connection and a closed valve at the rear of the rear-most trailer.

Question 4 of 20

When you uncouple a converter dolly, you should:

Disconnect air and electrical, secure or remove safety chains, then release the pintle hook
Just yank it off
Drive forward fast
Use only the trailer brake

Correct. Park level, disconnect air and electric, lower trailer landing gear if applicable, remove safety chains, then release the pintle hook to free the dolly.

Question 5 of 20

When traveling on bridges with weight or length limits:

Verify the rig's overall length and weight comply with posted limits
Ignore signs
Drive faster
Honk the horn

Correct. Multi-trailer rigs may exceed length or weight limits on certain bridges. Plan routes to comply with posted limits.

Question 6 of 20

The "T" endorsement is required to:

Drive any commercial vehicle
Pull two or more trailers
Drive a bus
Haul hazmat

Correct. The T endorsement is required to pull more than one trailer (doubles or triples).

Question 7 of 20

In a multi-trailer combination, the most violent movement during evasive maneuvers happens at:

The tractor
The first trailer
The last trailer
The cab

Correct. Rearward amplification (crack-the-whip effect) is greatest at the rear-most trailer. The last trailer in a triple can be thrown sideways with much greater force than the tractor.

Question 8 of 20

The driver of a doubles rig should:

Make slow, gradual steering and braking inputs
Drive aggressively
Use only the trailer brake
Honk frequently

Correct. Smooth, gradual inputs are critical. Avoid abrupt steering and abrupt braking.

Question 9 of 20

Driving doubles or triples on the highway:

Requires gentler steering, longer following distance, and earlier braking
Allows the same maneuvers as a single trailer
Allows higher cornering speeds
Has no special concerns

Correct. Multi-trailer rigs are more sensitive to abrupt steering, take longer to brake, and amplify any movement to the rear. Be gentle and plan ahead.

Question 10 of 20

Safety chains on a converter dolly are required to:

Prevent the dolly from disconnecting if the pintle hook fails
Decorate the rig
Bind cargo
Add weight

Correct. Safety chains catch the dolly if the pintle hook releases or fails — preventing the trailer behind from breaking loose.

Question 11 of 20

You discover a flat tire on the rear trailer of a triple. You should:

Continue driving
Pull off safely, set warning devices, and have the tire repaired or replaced before continuing
Drive only at night
Drive faster to balance

Correct. A flat tire affects rig stability and brake load. Pull off safely, use warning devices, and address the tire.

Question 12 of 20

Doubles and triples should not be driven:

On slippery roads at normal speed
On dry, straight highways
In any conditions
Only at low speed

Correct. On slippery roads, multi-trailer rigs lose stability quickly. Reduce speed substantially and increase following distance.

Question 13 of 20

A "set of doubles" typically refers to:

A tractor pulling two trailers
One tractor with one long trailer
Two tractors and a trailer
Two tractors and two trailers

Correct. A "set of doubles" is one tractor pulling two trailers (typically two pups, each about 28 feet long, in LTL operations).

Question 14 of 20

Glad-hand shut-off valves at the rear of trailers (for connecting to a following trailer) must be:

Open at the rear of the rear-most trailer
Open at the rear of any trailer that has another trailer behind it; closed at the rear of the last trailer
Always closed
Always open

Correct. Open the shut-off valves where the next trailer is connected; close them at the rear of the last trailer to prevent air loss.

Question 15 of 20

On a triple, the air pressure to the rearmost trailer:

Is the same as the lead
Is delayed by line length, so braking response at the rear trailer lags noticeably
Is faster
Does not exist

Correct. Greater line length = greater brake-lag at the rear. Plan braking earlier than you would for a single trailer.

Question 16 of 20

When pulling triples, you should:

Make abrupt lane changes
Drive in the right lane and avoid abrupt steering
Drive in the left lane
Drive at top speed

Correct. Stay right, plan lane changes well in advance, signal early, and avoid abrupt steering. Triples crack-the-whip violently.

Question 17 of 20

A tractor pulling doubles cannot brake as quickly as a tractor pulling a single trailer because:

Doubles are heavier and brake response is delayed in longer air lines
Doubles are lighter
Brakes are bigger
Tractors brake better with doubles

Correct. Greater weight and longer air lines mean longer braking distance. Plan stopping distance with extra margin.

Question 18 of 20

Triples are restricted in many states. You should:

Drive triples anywhere
Verify state-by-state legality before crossing into a state
Use a special placard
Avoid driving in cities

Correct. Many states restrict triples to specific routes (turnpikes, designated corridors). Verify legality and route before crossing into a state.

Question 19 of 20

A converter-dolly fifth wheel must be:

Properly lubricated and have correctly functioning locking jaws
Painted
Wide
Empty

Correct. Inspect for proper lubrication, no excessive wear, and confirm the locking jaws operate correctly. The dolly fifth wheel is just as critical as the tractor's.

Question 20 of 20

Air pressure on a triple-trailer rig takes:

Less time to reach the rear trailer than on a single
Significantly more time to reach the rear trailer's brake chambers
The same time
No air pressure is needed

Correct. Each additional trailer adds line length. Brake response at the rear trailer of a triple is noticeably delayed — brake earlier.

About the New Hampshire Doubles/Triples exam

Most states administer 20 Doubles/Triples questions and require 80% to pass. The exam emphasizes coupling and uncoupling the converter dolly, rearward amplification (the "crack-the-whip" effect), and the unique inspection and handling demands of multi-trailer rigs.

The New Hampshire Division of Motor Vehicles follows the federal CDL standards established by FMCSA. To earn the Doubles/Triples 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 Doubles/Triples question bank or browse all New Hampshire CDL practice tests.