A terminal tractor includes a fifth wheel coupling which is rotatable relative to a longitudinal axis of the terminal tractor such that an opening in the fifth wheel coupling may be reoriented depending on the terminal tractor's direction of approach to a semi-trailer.

A trailer assembly with improved lateral support structure and steering system control of the axial wheels on a front elongated trailer and a rear elongated trailer to remain in a collinear following configuration to carry elongated loads extending over the extended lengths of the combination of the front elongated trailer and the rear elongated trailer and allow ready turning control.

A breakaway fifth wheel coupling may couple a semi-tractor to a semi-trailer. In one embodiment, a breakaway fifth wheel coupling may include a top plate, a bottom brace, and a release mechanism that releasably attaches the top plate to the bottom brace. When a rollover event is detected, the release mechanism may allow the top plate to release from the bottom brace, thereby allowing the semi-tractor to separate from the semi-trailer. The fifth wheel coupling may include a pair of pivot rails that promote consistent decoupling of the top plate from the bottom brace. The breakaway fifth wheel coupling may reduce the likelihood of the semi-tractor participating in a rollover accident.

A fifth wheel control arrangement (100) for an articulated vehicle comprising a fifth wheel having a biased hinge joint and an actuator (115) arranged to control a biasing force and/or a damping force of the biased hinge joint. The control arrangement comprises a control unit configured to automatically control the actuator in response to one or more input sensor signals associated with a current state of the articulated vehicle, to obtain a target wheel axle load of the articulated vehicle and/or to stabilize the articulated vehicle.