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MD · T Endorsement

Maryland Doubles / Triples CDL Practice Test

Below are 25 exam-style questions for the Maryland Doubles / Triples CDL knowledge test, modeled on the FMCSA-aligned content used by the Maryland Motor Vehicle Administration. Try to answer each question on your own before reading the answer key directly under it. The questions and answer choices are shuffled deterministically per state and endorsement, so the order will stay the same on repeat visits — that lets you genuinely measure your improvement.

Heads up: this is a study tool, not a graded exam. Cover the answer with your hand or a sheet of paper for an honest practice run, then re-read the explanations for any questions you missed. Aim for 22 out of 25 or better, three times in a row, before scheduling the real exam.
Question 1 of 25
When you must change lanes in a doubles combination:
  • A Change at high speed
  • B Signal early and change smoothly to minimize swing
  • C Change in heavy traffic
  • D Change quickly without signaling
Correct answer: B
Smooth lane changes reduce trailer swing.
Question 2 of 25
When you couple the second trailer to the converter dolly:
  • A Trust visual inspection only
  • B Verify the fifth wheel locks around the kingpin and test by tugging gently
  • C Couple at high speed
  • D Skip the lock verification
Correct answer: B
Verification prevents the catastrophic loss of the second trailer.
Question 3 of 25
The pintle hook safety latch:
  • A Is electrical
  • B Prevents accidental release of the hook
  • C Is decorative
  • D Is the same as a fifth wheel jaw
Correct answer: B
Safety latch ensures the hook cannot release accidentally.
Question 4 of 25
When the driver brakes a doubles combination:
  • A Brakes are uneven
  • B All trailers should brake together if the system is functioning correctly
  • C Only the first trailer brakes
  • D Only the rear trailer brakes
Correct answer: B
Air-brake system applies all wheels simultaneously when functioning correctly.
Question 5 of 25
A doubles/triples driver should be especially aware of:
  • A All of the above
  • B Crosswind effects on the rear trailer
  • C Potential rollover at curves
  • D Lane changes that swing the rear
Correct answer: A
All three considerations apply to multi-trailer combinations.
Question 6 of 25
When inspecting safety chains:
  • A Tie them in knots
  • B Allow them to drag
  • C Verify they are crossed under the pintle hook and not dragging
  • D Skip the inspection
Correct answer: C
Crossing chains catches the trailer if the hook fails; dragging chains can damage roadway and themselves.
Question 7 of 25
A doubles/triples driver should test the trailer brakes:
  • A Once a year
  • B Never; the dispatcher tests them
  • C Only at the destination
  • D Before pulling away from the coupling site
Correct answer: D
Test trailer brakes immediately after coupling and before any movement.
Question 8 of 25
A doubles combination requires:
  • A Air lines from tractor to first trailer to dolly to second trailer
  • B No air-brake system
  • C Mechanical brakes only
  • D Air lines only on the tractor
Correct answer: A
Air system extends through the entire combination via glad hands at each connection.
Question 9 of 25
When uncoupling a converter dolly:
  • A Skip the parking brake
  • B Allow the dolly to roll
  • C Disconnect at high speed
  • D Set the parking brake or chock the wheels before disconnecting
Correct answer: D
Brake setting prevents dolly movement during disconnect.
Question 10 of 25
When the converter dolly's air tank is empty:
  • A Use the trailer hand valve to charge
  • B Skip the charge
  • C Charge it before coupling and verify pressure
  • D Couple without checking
Correct answer: C
Charging the dolly's tank ensures the trailer brakes will release properly.
Question 11 of 25
A doubles/triples driver should always:
  • A Skip the pre-trip
  • B Use the trailer hand valve as a parking brake
  • C Drive as if it were a single trailer
  • D Be aware of the increased complexity of the equipment and operate accordingly
Correct answer: D
Awareness of complexity is essential for safe operation.
Question 12 of 25
When you need to back a doubles combination:
  • A Avoid it; if necessary, uncouple to a single trailer first
  • B Use only mirrors
  • C Have a passenger guide you
  • D Back at full speed
Correct answer: A
Backing doubles is extremely difficult; uncouple if possible.
Question 13 of 25
When pulling doubles, the driver should be alert to:
  • A Crosswind sensitivity
  • B All of the above
  • C Reduced visibility around the second trailer
  • D Increased rollover risk in curves
Correct answer: B
All three are inherent to multi-trailer operations.
Question 14 of 25
A doubles driver should be aware of:
  • A No specific length
  • B Tractor length only
  • C Trailer length only
  • D Total combination length when turning, parking, and changing lanes
Correct answer: D
Total length affects every maneuver.
Question 15 of 25
When a triple combination encounters a tight turn:
  • A Plan the turn carefully and use multiple lanes if necessary
  • B Turn sharply
  • C Maintain speed
  • D Skip the planning
Correct answer: A
Triples require careful planning for tight turns due to extreme off-tracking.
Question 16 of 25
Safety chains on a doubles combination:
  • A Are required only on triples
  • B Are decorative
  • C Provide a backup connection in case the primary coupling fails
  • D Carry electrical signals
Correct answer: C
Safety chains hold the trailer if the primary coupling fails.
Question 17 of 25
Coupling order for doubles is generally:
  • A Tractor to second trailer first
  • B Trailers first, then tractor
  • C Random order
  • D Drop first trailer, hook converter dolly to first trailer, back tractor to second trailer, etc.
Correct answer: D
Doubles coupling has a specific order to ensure stability and safety.
Question 18 of 25
When the rear trailer of a doubles combination begins to sway:
  • A Steer sharply to correct
  • B Brake hard
  • C Reduce speed gradually and avoid sudden steering inputs
  • D Accelerate
Correct answer: C
Smooth reduction in speed allows the trailer to settle.
Question 19 of 25
A doubles/triples driver should never:
  • A All of the above
  • B Skip the brake-light test
  • C Skip the air-leak rate check
  • D Skip the parking-brake test
Correct answer: A
All three are required for safe operation.
Question 20 of 25
A "pup" trailer is:
  • A A trailer for transporting animals
  • B A tractor only
  • C A short trailer commonly used in doubles and triples
  • D A converter dolly
Correct answer: C
"Pup" is the common term for a short trailer used in multi-trailer combinations.
Question 21 of 25
A doubles/triples driver should know that:
  • A T endorsement allows triples everywhere
  • B Restrictions apply only to hazmat
  • C Federal and state rules vary; T endorsement does not override route restrictions
  • D There are no restrictions
Correct answer: C
Endorsement allows you to pull; route restrictions still apply.
Question 22 of 25
A "coupling device" on a converter dolly:
  • A Is the same as a tractor fifth wheel
  • B Is electrical only
  • C Is a single hook
  • D Includes a pintle hook on the front and a fifth wheel on the back
Correct answer: D
Converter dollies have both ends: pintle hook to attach to the lead trailer, fifth wheel for the trailing trailer's kingpin.
Question 23 of 25
A driver pulling doubles or triples should drive in:
  • A The right lane on multilane highways when possible
  • B Any lane
  • C The shoulder
  • D The left lane
Correct answer: A
Slower lanes are safer for long combinations.
Question 24 of 25
A doubles/triples driver who experiences trailer swing should:
  • A Accelerate
  • B Brake hard
  • C Steer sharply to correct
  • D Reduce speed gradually and avoid sudden steering inputs
Correct answer: D
Gradual reduction lets the trailer settle without overcorrection.
Question 25 of 25
When a doubles combination is parked:
  • A Leave brakes off
  • B Set only the tractor parking brake
  • C Use the trailer hand valve
  • D Set parking brakes on the tractor and on the trailers
Correct answer: D
All parking brakes set for stable parking.

Study tips for the Maryland Doubles / Triples exam

The Doubles / Triples portion of the Maryland CDL exam is graded out of the bank of questions the Maryland Motor Vehicle Administration draws from each year. While the exact bank is not published, every question is sourced from the Doubles / Triples chapter of the Maryland CDL handbook, which itself is derived from the FMCSA Model Commercial Driver's License Manual. That means studying our practice tests, reading the corresponding handbook chapter, and re-reading the parts you got wrong is genuinely the most efficient route to a first-time pass.

Most successful applicants follow a simple cycle: take the practice test cold, write down every question you missed, open the matching chapter of the official Maryland handbook, re-read the section that contains the right answer, then re-take the practice test 24 to 48 hours later. The 24-hour delay matters — sleep is when your brain commits new information to long-term memory, and CDL knowledge questions reward that kind of consolidated learning rather than cramming.

Pay particular attention to questions that include qualifier words like always, never, only, primary, or most. CDL test writers love to flip the right answer with a single qualifier. When two answer choices look almost identical, pay attention to the verb (is it must, should, or may?) and to any numbers (14 days, 100 air miles, 8 hours, 70/8 split). On endorsement tests in particular, watch for trick framing where a true statement about a different endorsement is offered as the "correct" answer to a question that is actually about Doubles / Triples.

Test-day logistics matter too. Bring photo ID, your Social Security card or birth certificate, your medical examiner's certificate (DOT card), and proof of state residency if you haven't already submitted those documents. The Maryland Motor Vehicle Administration will not let you sit for the knowledge exam without your documentation, and most offices charge an additional fee for re-attempts. Arrive early — the wait at most CDL testing offices runs 30 to 60 minutes — and silence your phone before the exam begins.

Finally, keep your General Knowledge fundamentals sharp even when you're focused on the Doubles / Triples exam. Many states administer multiple knowledge tests in a single sitting, and questions on weight definitions (GVWR, GCWR, GAWR), stopping distance, and the pre-trip inspection routine show up across endorsements. If you're unsure on the basics, sit a fresh Maryland General Knowledge practice test before scheduling the real exam.

Next steps

Missed more than four questions? Re-read the Doubles / Triples study guide and the matching chapter in the official Maryland CDL handbook. Then come back and re-take the test. Once you can score 22 of 25 or higher on three runs in a row, you're in good shape to schedule the real exam at your local Maryland Motor Vehicle Administration office.

Already comfortable with this endorsement? Drill another: MD General Knowledge · MD Air Brakes · MD Combination Vehicles · MD Hazardous Materials · MD Passenger · MD School Bus · MD Tank Vehicle

New to the CDL process in Maryland? Read How to apply for a CDL in Maryland for the document checklist and step-by-step timeline.