NJ CDL Doubles/Triples study plan
NJ CDL Doubles/Triples · Give each week a clear focus.
8 weeks · About 6 hours per week
Coupling and uncoupling twin trailers
Memorize the full coupling sequence for twin trailers from tractor to second trailer, reciting each step and the reason it comes in that order
Identify every component of a converter dolly by name and function, including the pintle hook, lunette eye, dolly landing gear, and air lines
Explain why the second trailer's air lines must be connected and checked before the supply valve is opened
List the three most common coupling failures in doubles work and the physical symptom each one produces
Your checkpoint
A written, numbered coupling checklist of at least 15 steps with a one-sentence justification for each step, self-quizzed to 100 percent accuracy from memory
Coupling and uncoupling twin trailers & Inspecting converter dollies and the second trailer
Recite the uncoupling sequence in reverse order and state the order in which air lines and electrical cords are disconnected
Describe how to verify the pintle hook latch is fully closed and seated on the lunette eye using both a visual check and a physical tug test
Explain the correct procedure for raising and lowering dolly landing gear and where the dolly should be parked when dropped
Identify the inspection points unique to the second trailer that do not exist on a single trailer
Your checkpoint
A side-by-side coupling versus uncoupling comparison table with at least 12 matched step pairs and the safety consequence of getting each step out of order
Inspecting converter dollies and the second trailer
Build a complete pre-trip inspection walkaround order for a doubles or triples combination covering tractor, first trailer, dolly, and rear trailers
List the specific dolly inspection items including frame cracks, pintle hook wear, safety pin, air line condition, and mud flap and light function
Describe how to check that the rear trailer's brakes apply and release in sync with the tractor using the tractor protection valve
Explain what to look for in the air line gladhands and couplers that indicates a leak or a mismatched connection
Your checkpoint
A full written pre-trip inspection script of at least 30 checkpoints in walkaround order, timed to finish in under 30 minutes without notes
Braking and stopping with doubles/triples
Explain how braking distance and stopping time change when pulling two or three trailers versus a single trailer
Describe the correct use of the trailer hand valve and why it should not be used for parking
State the procedure for a brake check on a multi-trailer combination including the static and rolling tests
Identify the signs of brake lag or uneven braking across trailers and the action to take
Your checkpoint
A one-page braking reference sheet covering stopping distance factors, hand valve rules, and the full brake check procedure, scored at least 90 percent on a self-made 20-question quiz
Milestones
Week 4: Recite the coupling and uncoupling sequences and complete the 30-point pre-trip script from memory in one sitting with no more than two errors
Week 6: Explain offtracking, sway control, and backing rules aloud for 10 minutes without notes, covering all three domains studied so far
Week 8: Score at least 90 percent on a timed 50-question mixed practice test spanning all eight domains, with no domain below 80 percent