A slowing device includes a flexible slowing member that extends transversely to the trajectory of sheets being fed. The member is movable between at least two limit positions, one in which its trajectory encounters that of the sheets, the other in which the slowing member is moved aside from the trajectory of the sheets. A drive device moves the slowing member between its limit positions. The drive device for the slowing member includes a pneumatic actuator which acts on a linear cam that pivots about a transverse shaft. A roller rolls along the surface of the linear cam. The roller and the slowing member are supported by a support that pivots about a transverse shaft.