180 from the position shown in broken lines in fig7 and then turned rearwardly to the solid line position wherein the gate lies across the top of the stack and supports the incoming stream of carton blanks being fed to the machine the gate is held in its horizontal position shown in fig7 by reason of the engagement of the rods and their bottom strap 184 with the horizontal flange portion of the support member 178 operation of the machine described above is as follows the operator rolls the machine to a position behind a cutter on a printing press or behind a pair of single sheet feed conveyors and adjusts the bolts 26 to lock the machine in appropriate position to receive the feed streams over the rear of the machine and against the front finger stops 140 both elevators 28 in chambers a and b are elevated to their upper positions as illustrated at the right of fig4 with motor 102 operating the jogger plates 90 90 39 oscillate in the manner explained and force the carbon blanks or sheets against the forward stop fingers 140 and the center partition wall 20 so that the sheets form precise stacks on the elevators with their marginal edges accurately aligned as the stacks are being formed by the incoming sheets when one of the elevators 28 30 approaches its lowermost position at the bottom of chamber a or b the operator de energizes the appropriate motor 54 56 and stops the elevator at this time the operator immediately lifts the chamber gate 182 184 and swings it inwardly to a horizontal position above the completed stack as depicted in solid lines in fig7 the gate rods 182 serve as a bottom supporting surface.