Patent ID: 7648153

Claim:
Control device for a tractor having a longitudinal geometrical center axis and a system for detecting pivoting or articulating angles between the longitudinal geometrical center axis of the tractor and a longitudinal geometrical center axis of a semitrailer coupled by way of a kingpin when the semitrailer is being coupled and being pulled into and out of parking places, the semitrailer having an underside, characterized by a configuration ( 20 ) of a plurality of Hall sensors ( 21 ) located next to each other in an area which encloses a receiving opening ( 11 ) of the tractor for a fifth-wheel kingpin concentrically on a partial circular arc around the vertical geometrical center axis of the receiving opening; by at least one permanent magnet ( 30 ) which is located on the underside of the semitrailer at a radial distance (r m ) from the geometrical vertical axis ( 13 ) of the kingpin and with a distance to the Hall sensors such that with its magnetic field the at least one permanent magnet acts on and excites only the most closely adjacent Hall sensor of the configuration, and by electrical output lines of the Hall sensors ( 21 ), which lines are connected to an evaluation circuit that determines from the location of the excited Hall sensor an angle α between the longitudinal geometrical center axis of the tractor and the longitudinal geometrical center axis of the semitrailer.