FIELD: mechanical engineering. SUBSTANCE: invention relates to rotary support devices for automobile and tractor trailers. The slewing support device of a biaxial trailer contains a traction lever pivotally connected to the tractor, a turntable consisting of two round plates - the upper and the lower, connected by means of a pivot pin. The upper plate of the turntable is connected to the frame of the trailer body by means of brackets and a horizontal transverse axis, and the lower plate is connected to the frame of the front pivot bogie by means of brackets and a horizontal transverse axis. A driving power hydraulic cylinder is attached to the traction lever of the front wheeled bogie, the rod of which is connected to the tractor via a hinge. The master power hydraulic cylinder is connected through a closed hydraulic system with a working power hydraulic cylinder mounted on the frame of the front bogie, the rod of which is pivotally connected to the lower plate of the turntable. EFFECT: reduction in the longitudinal inclination angle of the turntable pivot pin in order to reduce the turning resistance without using the tractor's hydraulic system and allowing to reduce the lateral horizontal deviations of a biaxial trailer during straight-line motion. 1 cl, 3 dwg.