A seat base frame has pairs of tracks, each having an upper rail longitudinally displaceably guided relative to a lower rail and lockable by means of a locking device on the lower rail. A seat structure is connected to the upper rails, and a transverse support extends substantially perpendicular to the upper rails and is connected thereto. The transverse support is fixed in the axial direction thereof relative to the upper rails and rotatably connected thereto, wherein an actuating lever and a control lever are disposed rotationally fixed relative to each other and spaced apart from each other on the transverse support such that each can be engaged by a locking device for adjusting the locking device between a locked position fixing the upper rail relative to the lower rail and a release position releasing the upper rail relative to the lower rail.