Abstract: In a cassette loading and unloading apparatus, a device is provided for centering X-ray film cassettes of various sizes, which can be transported on rollers (19), by means of two parallel bars (16, 17) movable towards and away from each other, respectively. The bars (16, 17) have U-shaped recesses (16a, 17a) for passage of rollers (19). Of the lugs of bars (16, 17) formed by the recesses and projecting through the rollers, one lug (16b, 17b) of each bar (16, 17) is slidably guided on a guide rail (14) extending below rollers (19). Moreover, a second lug (16f, 17f) of each bar (16, 17) is in engagement with a driving mechanism (30, 34, 38, 45). The rollers (19), the guide rail (14) and the bars (16, 17) are arranged on the upper side of support plate (10), and the driving mechanism (30, 34, 38, 45) is provided on the lower side of that plate. They jointly form a prefinished assembly unit. FIGS. 1 and 2 are to be published.

Abstract: A sheet feeder includes a supply tray from which the paper sheets are individually withdrawn from the bottom of the stack. The stack supporting bottom of the tray is inclined relative to a horizontal plane, its angle of inclination being adjustable. The inclination of a supported stack can be adjusted according to stack weight or height. The weight of the sheet stack exerting pressure on stack support and/or the sheet separating device can thereby be controlled such that uniform sheet removal conditions are achieved.