Sheet-extracting device with a cassette for receiving a stack of sheets

A sheet-extracting apparatus with a cassette for receiving a stack of sheets, said sheet-extracting device comprising:

• an extracting apparatus having at least two extracting rollers for abutting against a top sheet which is to be extracted;
• a pressing device that can press a front end side of said stack, with a pressing force against said extracting device;
• a guide fork having a plurality of legs, said legs directed perpendicularly with respect to a plane of said sheets;
• a drive shaft having a first end rotatably mounted in a frame-mounted bearing and a displaceable end opposite the first end of said drive shaft displaceably mounted perpendicularly with respect to said plane;
• a universal joint;
• a tubular floating shaft having a central section, said tubular floating shaft connected to said drive shaft in a rotationally fixed manner;
• said rollers of said extracting device being arranged axially spaced from one another on said tubular floating shaft, the central section of said tubular floating shaft mounted with radial play on said drive shaft via said universal joint means, said drive shaft passing through said tubular floating shaft in a longitudinal direction, said tubular floating shaft adjustably guided between said plurality of legs of said guide fork;
• a pressing motor that can displace said pressing device against the rear end of said stack;
• a spring which acts on said displaceable end of said drive shaft, said pressing force determined by said spring, said spring having an excursion displacement which is a measure of said pressing force;
• a displacement sensor for measuring said excursion displacement of said spring, said sensor located near the displaceable end of said drive shaft;
• and
• said cassette removable from said sheet-extracting device and fittable thereon, said drive shaft assuming a first displacement position when said cassette has been removed and a second displacement position when said cassette has been fitted to said sheet-extracting device, said displacement sensor having a measuring range, said measuring range determining an absence or a presence of said cassette, and in the direction of increasing excursion of said spring, said measuring range is adjoined by a further measuring range through which said displacement sensor measures said pressing force of said stack of sheets on said extracting device and emits a signal for readjusting said pressing motor, dependent on said pressing force.