Sheet feeder

Sheet feeding apparatus comprising:

• a. means for removing successive top sheets from a stack of sheets, said removing means including feed roller means and vacuum means, the vacuum means operatively connected to the feed roller means for lifting successive top sheets off the stack and into engagement with the feed roller means for transportation thereby away from the stack;
• b. primary means for positioning the stack, said primary positioning means including a platform for supporting the stack thereon and means for moving said platform;
• c. first top sheet sensing means for sensing successive top sheets of the stack, said first top sheet sensing means adapted to incrementally operate the platform moving means for elevating the platform to maintain a supply of top sheets of the stack in operative engageable relationship with the removing means;
• d. secondary means for positioning the stack, said secondary positioning means including at at least one deck for supporting a reserve portion of the stack and means for moving said at least one deck;
• e. means for sensing a first level of the platform, said first platform level sensing means adapted to operate the deck moving means for moving said at least one deck into supporting engagement with the stack reserve portion, said first platform level sensing means adapted to operate said platform moving means for lowering the platform to a second level to permit loading thereon a replenishing supply of sheets;
• f. said first top sheet sensing means adapted to incrementally operate the deck moving means for elevating said at least one deck to maintain the supply of top sheets in operative engageable relationship with the removing means;
• g. means for operating said platform moving means to raise the platform from said second level after the replenishing supply has been loaded thereon;
• h. second top sheet sensing means for sensing a level of the top sheet of the replenishing supply, said second top sheet sensing means adapted to operate said deck moving means for disengaging the deck from the stack reserve portion to permit engagement with the replenishing supply, whereby the stack reserve portion is combined with the replenishing supply on the platform to form therewith a new stack of sheets.