A tractor stays upright during an abrupt lane change. Does that alone show that its trailer was safe from rollover?
Correct answer: No; the trailer can overturn while the tractor stays upright
A sharp steering movement can be amplified toward the rear of a combination. The trailer may overturn even when the tractor does not, so the tractor's behavior alone does not establish the trailer's stability.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-1, physical 82 > 6.1.2 Steer Gently ↗
Before departure, a semitrailer leans because heavy cargo is concentrated along one side. Which loading change addresses that added rollover risk?
Correct answer: Redistribute the cargo so the load is centered
A load concentrated on one side can make the trailer lean and increase rollover risk. Centering the cargo addresses that lateral imbalance; securing the load and controlling speed remain necessary.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-1, physical 82 > 6.1.1 Rollover Risks ↗
During hard braking, the trailer starts moving sideways relative to the tractor. Which observation gives the driver an early chance to recognize this?
Correct answer: The trailer's movement in the mirrors
The manual identifies mirror observation as the earliest and best way to detect the beginning of a trailer skid. Detection becomes more difficult to act on once the trailer has swung out of its lane; this item is not a skid-recovery procedure.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-2, physical 83 > 6.1.5 Prevent Trailer Skids > Recognize the Skid ↗
A tractor-trailer driver swings left before starting a tight right turn, leaving a large opening on the right. What additional hazard does that setup create?
Correct answer: Another driver may enter the opening on the right
Swinging left before a right turn can invite traffic into the space the turning combination needs. The manual advises keeping the rear close to the curb while allowing sufficient clearance for the turn and people nearby.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-3, physical 84 > 6.1.6 Turn Wide ↗
In a clear practice area, a straight tractor-semitrailer begins backing. The driver wants the trailer's rear to start moving left. Which initial steering input produces that response?
Correct answer: Turn the top of the wheel right
At the start of a backing turn, trailer steering works opposite to backing a single vehicle. An initial movement of the top of the steering wheel to the right starts the trailer left; later steering must change to follow its path.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-3, physical 84 > 6.1.7 Backing with a Trailer ↗
While backing a tractor-semitrailer slowly along a straight, clear path, the trailer begins drifting right. Which early correction does the manual describe?
Correct answer: Turn the top of the steering wheel toward the right
To correct a trailer's drift during backing, turn the top of the steering wheel in the direction of the drift. Slow movement gives time for small corrections before the trailer gets far off its intended path.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-4, physical 85 > 6.1.7 Backing with a Trailer > Correct Drift Immediately ↗
A trailer's backing angle has become awkward, and there is room to reposition safely. Which action does the manual support?
Correct answer: Stop and make a forward pull-up as needed
A driver may pull forward to reposition the combination during backing. Continuing an unsuitable backing path is not a requirement; the area must be checked before any movement.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-4, physical 85 > 6.1.7 Backing with a Trailer > Pull Forward ↗
A tractor protection valve fails to work correctly when a large leak develops in a trailer air hose. What additional danger does that failure create?
Correct answer: The trailer leak can drain the tractor's air supply
The protection valve is intended to preserve air in the tractor when the trailer system has a serious leak. If it fails, air loss can spread to the tractor and cause emergency brake application with possible loss of control.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-14, physical 95 > 6.5.2 Combination Vehicle Brake Check > Test Tractor Protection Valve (continued from printed 6-13) ↗
A disconnected trailer air coupler has grit on its rubber seal. What should happen before the couplers are joined?
Correct answer: Clean the couplers and their rubber seals
Glad-hand rubber seals help make the air connection leak-tight. The manual calls for cleaning the couplers and seals before connection; trapped dirt should not be treated as something normal air pressure will repair.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-5, physical 86 > 6.2.5 Hose Couplers (Glad Hands) ↗
A tractor's air hoses are not color-coded, but each has a readable metal identification tag. What should guide the connection to the trailer?
Correct answer: The service and emergency labels on the tags
The manual describes both color coding and metal tags as ways to identify the lines. Match service to service and emergency (supply) to emergency; hose reach or position is not a reliable substitute.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-5, physical 86 > 6.2.5 Hose Couplers (Glad Hands) ↗
After connecting a spring-brake-equipped trailer, its spring brakes do not release when the trailer air supply control is pushed in. Which connection error should be checked?
Correct answer: Whether the service and supply air lines were crossed
Crossed lines can send supply air into the service line instead of charging the trailer reservoirs, leaving insufficient air to release the spring brakes. This is a possible cause to check, not proof that crossed lines are the only possible fault.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-6, physical 87 > 6.2.5 Hose Couplers (Glad Hands), continuation from printed 6-5 ↗
A tractor has dedicated dummy couplers for its air hoses. Why attach the disconnected glad hands to those fittings?
Correct answer: To keep water and dirt out of the air connections
Dummy couplers provide a protected place for unused air connections. Their purpose is to help keep contamination out, not to operate trailer brakes or the mechanical coupling.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-6, physical 87 > 6.2.5 Hose Couplers (Glad Hands), continuation from printed 6-5 ↗
