Abstract: In a device for holding down the lower cassette portion (19a) of an X-ray film cassette which is located in a cassette unloading and reloading apparatus, a hold-down lever (20, 21) is mounted to each of two parallely guided bars (10, 12) movable towards and away from each other respectively, said hold-down lever being pivotable into, and out of the transport path of the X-ray film cassette to accurately position said cassette. Each hold-down lever (20, 21) comprises a control arm (20a, 21a) resting against each of the two side walls (19d, 19e) of the upper cassette portion (19c). Since the control arms (20a, 21a) are upwardly inclined such that they form control surfaces facing the side walls (19d, 19e) of the upper cassette portion (19c), the hold-down levers (20, 21) are held in engagement with the lower cassette portion (19a) when the upper cassette portion (19c) is in its open position and are disengaged from the lower cassette portion (19a) when the upper cassette portion (19c) is in its closed position.

Abstract: In a photographic shutter, an opening blade and a closing blade are settable in respective tensioned positions from which the blades can be released to first uncover and then recover an exposure opening. A cam device is mounted for unidirectional rotation to release the blades from their tensioned positions and to reset the blades to such positions. The cam device has an arcuate camming surface which extends spirally about the axis of the cam device from an area of minimum radius to an area of maximum radius as the cam device is rotated. A step-like surface of the cam device connects the areas of maximum and minimum radii to cause an abrupt drop from the maximum radius area to the minimum radius area. Respective springs urge the opening and closing blades against the camming surface.