Abstract: A box machine is retrofitted by removing the upper feed roll, sheet feeder, and by replacing the lower feed roll with a drive shaft. A transport section and a sheet feeder are then inserted into the box machine. The transport section comprises transport wheels driven by the drive shaft which engage a sheet to transport it to the box machine without crushing. The sheet feeder comprises feed wheels driven by a servo motor for feeding the lowermost sheet of a stack to the transport section. A feed interrupter is movable from a raised stop-feed position to a lowered feed position by cams rotated by a servo motor. A controller coordinates the velocity of the feed wheels and position of the feed interrupter. Retrofitted machines eliminate the need to increase Edge Crush Test ratings of sheets from the corrugator 15% to 20% greater than printed in the certificate stamp.