Method and system for regulating the linear position of a fifth wheel

A system for regulating the linear position of a fifth wheel of a tractor unit while the tractor unit is in motion, the system comprising:

• a switching device operatively connected to the fifth wheel and configured for setting the fifth wheel in various linear positions relative to the tractor unit, in the tractor unit's longitudinal direction, in order to regulate the distance between the tractor unit and a semi-trailer coupled to the tractor unit via the fifth wheel, and
• an electronic control device configured and operable to control the switching device, and the control device is operable to determine a set-point value (fbör) for the linear position of the fifth wheel on the basis of the vehicle speed, and is operable to control the switching device on the basis of the set-point value (fbör),
• wherein the control device is configured and operable to control the switching device based on the set-point value (fbör) of the control device to cause the switching device to cause forward movement of the fifth wheel to reduce the distance between the tractor unit and the semi-trailer in response to an increase in the vehicle speed and to cause a faster rate of movement of the fifth wheel at times when the tractor unit is performing a gear change operation than at times when the tractor unit is not performing a gear change operation, and/or
• in response to a decrease in the vehicle speed, the control device causes the switching device to cause orders a rearward movement of the fifth wheel in order to increase the distance between the tractor unit and the semi-trailer, and
• the control device is configured and operable to simultaneously order braking of the semi-trailer relative to the tractor unit, in order thereby to facilitate the rearward movement of the fifth wheel.

A computer program product comprising computer program code programmed on a programmable data storage medium, in a tractor unit which is provided with a fifth wheel and the fifth wheel can by means of a switching device be set in various linear positions relative to the tractor unit, in the tractor unit's longitudinal direction, in order to regulate the distance between the tractor unit and a semi-trailer coupled to the tractor unit via the fifth wheel,

• the program being configured and operable for causing an electronic control device of the tractor unit to:
• receive or determine a value which represents the prevailing vehicle speed,
• determine a set-point value fbör for the linear position of the fifth wheel on the basis of the vehicle speed and control the switching device on the basis of that set-point value fbör, and
• control the switching device in such a way that forward movement of the fifth wheel to reduce the distance between the tractor unit and the semi-trailer in response to an increase in the vehicle speed is effected by the switching device at a faster rate of movement of the fifth wheel at times when the tractor unit is performing a gear change operation than at times when the tractor unit is not performing a gear change operation, and/or
• order braking of the semi-trailer relative to the tractor unit when the switching device has to effect a rearward movement of the fifth wheel in order to increase the distance between the tractor unit and the semi-trailer in response to a decrease in the vehicle speed, in order to facilitate the rearward movement of the fifth wheel.