Abstract: A device for holding down sheets which are stacked on a support has a vertical cylinder mounted above the support and provided with a piston and a piston rod extending from the piston through and to the outside of the cylinder where it carries a sheet-engaging member which exerts pressure on sheets resting on the support. A pair of conduits communicates with the cylinder chambers above and below the piston and a valve is provided which can either connect both conduits with a channel supplying compressed air or which can connect the conduit for the lower chamber with a suction channel. The positive or negative pressure in the respective conduits can be regulated.