A SHEET FEEDER FOR A SHEET PROCESSING MACHINE HAVING A CONTINUOUSLY RUNNING SHEET INTAKE

摘要

The invention relates to a sheet feeding apparatus for supplying a sheet fed processing machine having a continuously running intake with successive sheets, preferably without any gaps between their leading and trailing edges and comprising retractable front sheet guides for halting the sheets and sheet advancing means adapted to operate in step with the feeding operation, said advancing means being driven from a one-turn shaft, that times the feed operation and drives the advancing means through a transmission responsible for advancing or retarding the sheets in relation to the rotation of the one-turn shaft as a function of the size of the sheets, said transmission having an output shaft moving in steps. In order to make it possible for the processing machine to be supplied with two superposed sheets at a time the apparatus comprises two superposed sheet advancing means operating in step and having superposed front sheet guides and able to be moved in step and at the same speed. At least one advancing means has two sets of sheetpulls (which will primarily be suckers) adapted to engage the sheet alined therewith on one side thereof, said sheetpull sets being offset from each other across the apparatus and being driven backwards and forwards 180 DEG out of phase with each other by means of racks guided in the direction of transport and acting on the sheetpulls. The racks of one such set mesh with gear wheels keyed on a first shaft while those of the other mesh with gears bearinged on said first shaft and in mesh with gears keyed on a second shaft, parallel to the first shaft. There is a coupling for connecting the one or the other of the two shafts with the output shaft of the transmission alternately so that by virtue of a non-reversing connection between the shafts, they alternately turn in opposite directions.