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 ↗
The tractor's service-line signal reaches a trailer relay valve. Where does that valve obtain the air it sends to the trailer brakes?
Correct answer: From the trailer's air tank
The service line carries the control signal. The relay valve uses air stored in the trailer's tank to apply its brakes; the service signal does not itself provide the full supply for the trailer brake application.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-6, physical 87 > 6.2.6 Trailer Air Tanks ↗
The tractor and trailer air lines look secure while straight, but become taut as the rig turns. What needs correction before travel?
Correct answer: The lines need secure support with enough slack for turns
Trailer air lines need both proper support and enough slack for the combination to turn. A line that is tight only because the rig is straight has not passed that clearance check.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-13, physical 94 > 6.5.1 Additional Things to Check during a Walk-around Inspection > Coupling System Areas > Air and electric lines to trailer ↗
On a fifth wheel that requires grease, the plate has not received the required lubrication. What effect can that missing lubrication have?
Correct answer: Friction at the fifth wheel can impair steering
The fifth-wheel plate must be lubricated as required for its design. Excessive friction at that connection can cause steering problems; this does not prescribe one lubricant or service interval for every fifth wheel.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-7, physical 88 > 6.4.1 Coupling Tractor-Semitrailers > Step 1 Inspect Fifth Wheel ↗
A loaded semitrailer is waiting for its tractor. Why check cargo securement before the tractor backs into the coupling?
Correct answer: Coupling can move the trailer and shift unsecured cargo
The coupling inspection includes making sure cargo is secured against movement caused by the tractor coupling to the trailer. A stationary trailer still needs that protection before the maneuver starts.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-8, physical 89 > 6.4.1 Coupling Tractor-Semitrailers > Step 2 Inspect Area and Chock Wheels ↗
A tractor is positioned diagonally to a parked semitrailer before backing underneath it. What is the concern with continuing that approach?
Correct answer: It could push the trailer sideways and damage its supports
The manual calls for positioning the tractor directly in front of the trailer. Backing underneath at an angle can force the trailer sideways and break its landing gear.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-8, physical 89 > 6.4.1 Coupling Tractor-Semitrailers > Step 3 Position Tractor ↗
Before going beneath the trailer to inspect the coupling, the driver has set the parking brakes and placed the transmission in neutral. What further preparation does the manual specify?
Correct answer: Shut off the engine and take the key
The manual includes engine shutdown and taking the key so another person cannot move the truck while the driver is underneath it. These actions are part of securing the vehicle, not a replacement for the parking brake and neutral.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-8, physical 89 > 6.4.1 Coupling Tractor-Semitrailers > Step 12 Secure Vehicle ↗
During a properly prepared coupling-security check, the landing gear is slightly off the ground and the trailer brakes remain locked. How does the driver check that the coupling holds?
Correct answer: Pull gently forward against the braked trailer
A gentle forward pull against the locked trailer brakes checks that the trailer is attached to the tractor. The subsequent secured visual inspection is also required; this item describes only the pull portion of the procedure.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-8, physical 89 > 6.4.1 Coupling Tractor-Semitrailers > Step 11 Check Connection for Security ↗
A secured visual inspection shows the fifth-wheel jaws gripping the kingpin's enlarged head instead of its shank. How should that finding be treated?
Correct answer: As an incorrect coupling that must be corrected
The jaws belong around the kingpin's shank, not the enlarged head. A closed-looking control does not make incorrect jaw engagement safe; the coupling must be right before the rig is moved.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-13, physical 94 > 6.5.1 Additional Things to Check during a Walk-around Inspection > Coupling System Areas; Figure 6.8 ↗
The fifth-wheel locking lever is in its lock position, but the separate safety latch is not engaged. What does the inspection still require?
Correct answer: Put the safety latch in its proper securing position
The manual requires checking both the locking lever and the safety latch. Some fifth-wheel designs require the catch to be placed by hand, so lever position alone is insufficient.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-8, physical 89 > 6.4.1 Coupling Tractor-Semitrailers > Step 13 Inspect Coupling ↗
The trailer lights work during a check, but the electrical connector's safety catch has not been fastened. What remains to be done?
Correct answer: Fasten the connector's safety catch
The coupling procedure requires plugging in the electrical cord and fastening its safety catch. Working lights at one moment do not establish that an unsecured plug will remain connected.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-9, physical 90 > 6.4.1 Coupling Tractor-Semitrailers > Step 14 Connect the Electrical Cord and Check Air-lines ↗
The landing gear is fully raised, but its crank handle is hanging loose. What should the driver do before departure?
Correct answer: Secure the crank handle in its proper position
Raising the landing gear is followed by securing the crank handle. The walk-around also checks that the handle is in place and secure.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-9, physical 90 > 6.4.1 Coupling Tractor-Semitrailers > Step 15 Raise Front Trailer Supports (Landing Gear) ↗
After coupling, the trailer's full weight rests on the tractor. Which clearance does the manual specifically tell the driver to check at this stage?
Correct answer: The gap between the tractor tires and the trailer nose
With the trailer's weight on the tractor, the driver checks that the tops of the tractor tires have enough clearance below the trailer nose. A check made before the weight transfers does not establish this loaded clearance.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-9, physical 90 > 6.4.1 Coupling Tractor-Semitrailers > Step 15 Raise Front Trailer Supports (Landing Gear) ↗
A sliding fifth wheel has been moved forward. Which turning clearance must be checked before accepting that position?
Correct answer: Cab, trailer, frame, and landing-gear clearances
A fifth wheel too far forward can put the tractor frame against the landing gear or the cab against the trailer during a turn. The slide's position must leave adequate clearance.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-13, physical 94 > 6.5.1 Additional Things to Check during a Walk-around Inspection > Coupling System Areas > Sliding fifth wheel ↗
A sliding fifth wheel appears stationary, but one of its locking pins is missing. What does the manual's inspection require?
Correct answer: All locking pins must be present and locked in place
A stationary appearance does not verify the slide's locking system. The walk-around calls for every locking pin to be present and locked, as well as checking for other damage.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-13, physical 94 > 6.5.1 Additional Things to Check during a Walk-around Inspection > Coupling System Areas > Sliding fifth wheel ↗
A driver plans to leave a loaded semitrailer on ground that looks level but may be soft. What must be established about that parking surface?
Correct answer: That the surface can support the trailer's weight
Level appearance alone does not show that a parking surface will carry the trailer after the tractor is removed. The uncoupling procedure begins by checking the surface's ability to support that weight.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-9, physical 90 > 6.4.2 Uncoupling Tractor-Semitrailers > Step 1 Position Rig ↗
During uncoupling, the fifth wheel has cleared the trailer, but the driver pauses with the tractor frame still underneath. What is the reason for that intermediate position?
Correct answer: It helps support the trailer if the landing gear fails
The procedure retains the tractor frame beneath the trailer briefly as protection against failed or sinking landing gear. The driver then secures the tractor and verifies the trailer supports before pulling completely clear.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-9, physical 90 > 6.4.2 Uncoupling Tractor-Semitrailers > Step 7 Pull Tractor Partially Clear of Trailer ↗
After disconnecting a semitrailer, why does the manual say to hang the supported electrical cable with its plug pointing down?
Correct answer: To help prevent moisture from entering the plug
Pointing the disconnected plug downward helps keep moisture out. The cable must also be supported so it will not be damaged while the tractor moves.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-9, physical 90 > 6.4.2 Uncoupling Tractor-Semitrailers > Step 5 Disconnect Air-lines and Electrical Cable ↗
A pintle hook's latch closes, but its mounting is loose. Which assessment is correct?
Correct answer: The mounting can fail despite a closed latch
A pintle hook must be securely attached to its mounting surface as well as properly latched. A sound latch cannot compensate for a mounting that may separate from the tow vehicle.
Source: New Jersey CDL Manual, March 2025 cover; Section 6, July 2017 footer, printed 6-10, physical 91 > 6.4.3 Coupling a Pintle Hook > Step 1 Inspect Pintle Hook ↗
