Practice Exam Questions And Correct

CDL Double/Triple Trailers (T) Endorsement Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the main danger of off-tracking when driving double or triple

trailers?

• Reduced fuel efficiency
• Increased tire wear
• Rear trailers not following the path of the front trailer
• Lower speed limits

Off-tracking occurs when the rear trailers cut corners tighter than the tractor, increasing the risk of hitting curbs, vehicles, or pedestrians.

2. When coupling a double trailer, the trailer air lines must be connected:

• After pulling out of the lot
• Before backing under the kingpin
• Only after starting the engine
• Only if the tractor has a manual transmission 1 / 4

Air lines must be connected before backing under the kingpin to ensure brakes function and air flows correctly.

• How should you brake when descending a long, steep hill with

double/triple trailers?

• Apply full brakes continuously
• Downshift only
• Use a combination of engine braking and controlled brake

application

• Pump brakes rapidly

Continuous braking can cause brake fade. Using engine braking and controlled brake applications maintains control and prevents overheating.

• What is the maximum speed limit for a double or triple trailer on most

highways?

• 65 mph
• 60 mph
• 55 mph
• 50 mph

Many states and federal guidelines set a 60 mph speed limit for combination vehicles with double or triple trailers.

5. When backing a double/triple trailer, the best technique is:

• Turn the wheel sharply and quickly
• Have one person outside giving directions 2 / 4

• Turn the steering wheel in small, controlled amounts
• Back as fast as possible to reduce time

Small, controlled movements reduce the risk of jackknifing and allow better correction.

• What is a “converter dolly”?
• A type of brake system
• A trailer used to connect a second trailer to a tractor-trailer

combination

• A device to improve fuel efficiency
• A safety harness for the driver

A converter dolly is a two-axle trailer used to attach a second trailer behind the first.

• How often should you check the securement of your double/triple

trailers?

• Only at the start of the trip
• Every 200 miles
• Before driving and during inspections, especially after coupling
• Only when leaving a loading dock

Double/triple trailers must be checked frequently to prevent accidents caused by loose connections.

• What is the main hazard when making a right turn with a double/triple

trailer?

• Tires losing pressure 3 / 4

• Rear trailers cutting across lanes or hitting objects
• Engine stalling
• Losing the trailer brakes

The rear trailers track inside of the tractor's path, which may hit curbs, vehicles, or pedestrians.

9. When uncoupling a double trailer, the tractor must be:

• Running at high RPM
• Fully stopped with brakes applied
• Moving slowly forward
• On a hill

The tractor must be stopped and secured to prevent movement that could cause accidents or damage.

• What is a “jackknife” in combination vehicles?
• A tool for tire repair
• A type of hitch
• When the trailer swings out and forms a sharp angle with the

tractor

• A braking technique

Jackknifing occurs when the tractor and trailer fold in on each other, usually due to over-braking or loss of traction.

• How does the length of a triple trailer affect stopping distance?
• No effect
• Slightly reduces it
• / 4