Abstract: A balancing device for a portion (2), rotable about a horizontal axis (4) in a frame and provided with a lever arm (21) fixedly connected to the portion (2) to be balanced, a spring member (26) by means of a pull-or press member (40) connected to the lever arm (21) in which the pull-or press member (40) is directed through an approx. fixed point (30') in the frame and whereby in the position wherein the center of gravity (20) of the part to be balanced is positioned precisely above the hinge pin, the direction of the pulling or pressing forces (40) extends in longitudial direction of the lever arm (4-32-30'), the spring (26) having a linear characteristic and being biassed in a special way, the balancing device being especially suited for a platform sideboard or a tilting cab.