Two compatible semitrailers will form a set of doubles. One carries a much heavier load. Which order does the manual recommend for the safest handling?
Correct answer: Put the heavier trailer directly behind the tractor
The more heavily loaded semitrailer belongs in the first position behind the tractor, with the lighter one behind it. Working brakes do not make trailer order irrelevant to handling.
Source: New Jersey CDL Manual, March 2025 cover; Section 7, July 2017 footer, printed 7-1, physical 96 > 7.2.1 Coupling Twin Trailers, trailer-loading order paragraph. ↗
On a slippery grade, why does adding trailers call for extra caution even though the combination now has more axles?
Correct answer: The drive axles must pull more unpowered axles
The manual describes greater length and more dead, or unpowered, axles for the drive axles to pull. Additional trailer axles do not become powered axles, and adverse conditions increase the chance of skids and lost traction.
Source: New Jersey CDL Manual, March 2025 cover; Section 7, July 2017 footer, printed 7-1, physical 96 > 7.1.6 Adverse Conditions. ↗
Several parking spaces are long enough for your doubles, but some end at a wall. Which feature should guide your choice before entering a space?
Correct answer: A clear route that lets the combination pull straight through
For doubles and triples, the manual emphasizes choosing a place with a straight-through exit. Space to fit the parked rig alone does not establish that it can leave without a difficult backing maneuver.
Source: New Jersey CDL Manual, March 2025 cover; Section 7, July 2017 footer, printed 7-1, physical 96 > 7.1.7 Parking the Vehicle. ↗
A converter dolly has spring brakes and is ready to be repositioned under controlled conditions. Which release method does the manual specify for that design?
Correct answer: Use the dolly's parking-brake control
The manual distinguishes a dolly with spring brakes from the other dolly arrangement it describes. For the spring-brake-equipped dolly, use its parking-brake control; do not transfer the tank-drain release instruction to that design.
Source: New Jersey CDL Manual, March 2025 cover; Section 7, July 2017 footer, printed 7-2, physical 97 > 7.2.1 Position Converter Dolly in Front of Second (Rear) Trailer, brake-design alternatives. ↗
The first trailer has towed an empty converter dolly close to the second trailer for positioning. No rear trailer rests on the dolly yet. Before unhooking this dolly from the first trailer, what should happen to its support?
Correct answer: Lower the dolly support before unhooking
In this positioning method, the dolly support is raised for towing and lowered before the dolly is unhooked. This scenario concerns an unloaded dolly; it does not authorize releasing a pintle hook while a rear trailer is still on the dolly.
Source: New Jersey CDL Manual, March 2025 cover; Section 7, July 2017 footer, printed 7-2, physical 97 > 7.2.1 Position Converter Dolly in Front of Second (Rear) Trailer, tractor/first-semitrailer positioning sequence. ↗
A rear trailer is secured with its brakes locked and wheels chocked. Its height would let the converter dolly pass underneath without lifting the trailer at all. What adjustment is needed before coupling?
Correct answer: Lower it so the dolly will raise it slightly
The trailer should be slightly lower than the center of the dolly's fifth wheel so that backing the dolly underneath raises it slightly. The kingpin is part of the connection; it does not replace contact between the fifth-wheel plates.
Source: New Jersey CDL Manual, March 2025 cover; Section 7, July 2017 footer, printed 7-3, physical 98 > 7.2.1 Connect Converter Dolly to Rear Trailer, securement and height checks. ↗
A twin-trailer driver has inspected the tractor's fifth wheel but has not examined the converter dolly's fifth wheel. How complete is the coupling inspection?
Correct answer: Incomplete; the dolly's fifth wheel also needs inspection
The dolly has its own fifth-wheel coupling to the rear trailer. Doubles add critical components, and a satisfactory tractor coupling or successful movement does not establish that the dolly coupling passes its inspection.
Source: New Jersey CDL Manual, March 2025 cover; Section 7, July 2017 footer, printed 7-1, 7-2 and 7-4, physical 96, 97 and 99 > 7.1.3 Inspect Completely; Figure 7.1; 7.3.1 Coupling System Areas. ↗
A dolly's pintle-hook latch looks closed, but the dolly's eye is not seated in the hook. What does this mean for the connection?
Correct answer: It is incorrect and must be corrected before travel
The inspection calls for both the dolly eye to be in the trailer's pintle hook and the hook to be latched. A closed-looking latch or weight on the dolly does not make an unseated eye a correct connection.
Source: New Jersey CDL Manual, March 2025 cover; Section 7, July 2017 footer, printed 7-4, physical 99 > 7.3.1 Additional Checks, Double and Triple Trailers, pintle-eye and hook-latch checks. ↗
A spare tire sits in the converter dolly's carrier, but its retaining device is loose. What should be done before departure?
Correct answer: Secure the spare tire in its carrier
When a spare tire is carried on the converter gear, the manual requires checking that it is secured. Its weight and the dolly's need to articulate do not justify a loose tire.
Source: New Jersey CDL Manual, March 2025 cover; Section 7, July 2017 footer, printed 7-4, physical 99 > 7.3.1 Additional Checks, Double and Triple Trailers, spare tire on converter gear. ↗
A double is straight on firm, level ground and secured for uncoupling. Before the dolly is withdrawn from beneath the rear trailer, how should that trailer's landing gear be positioned?
Correct answer: Lowered enough to take some weight off the dolly
The rear-trailer uncoupling sequence lowers its landing gear enough to remove some weight from the dolly before the dolly is released and pulled out. These support steps accompany the specified brakes, chocks, line disconnections and latch sequence.
Source: New Jersey CDL Manual, March 2025 cover; Section 7, July 2017 footer, printed 7-3, physical 98 > 7.2.2 Uncoupling Twin Trailers, Uncouple Rear Trailer. ↗
