Abstract: A lifting device for swiveling a part of a piece of furniture includes a scissor jack attached to the part being swiveled and operated by a drive unit having a spindle and a gear motor which is connected to the scissor jack and runs along the spindle. Incorporated in the drive unit is a safety mechanism for stopping a movement of the scissor jack upon occurrence of a blockage. The safety mechanism includes a pair of disks rotatable about the spindle and engaging each other via a complementary tooth gearing provided about the perimeter of each disk. One disk is stationary and the other disk is a spring-loaded disk which is displaceable in axial direction relative to the one disk. In this manner, the disks can be disengaged upon blockage during downward movement of the scissor jack to disconnect the gear motor from its output element and to prevent a further movement of the scissor jack.