When piston rod 1 moves upward, compressed air is released from box 2 through a slit regulated by screw 5. Box 2 is closed by leather membrane 3, secured to the box by helical spring 4 whose ends are joined to form a ring. When rod 1 moves downward, air can be drawn in both through the slit and through ball valve 6.
$4112$EHP,Rg$