Expansible plug valve having a rectilinear motion

Claim 1

A valve comprising a housing having a chamber, said chamber having an open end, a valve member comprising an elastometric plug adapted to be positioned in the chamber and to be removed therefrom, said plug having a flow-through opening, means applying compressive pressure to said elastometric plug to expand the same so that it is sealed against leakage in the chamber, said means comprising a top plate and a bottom plate for the plug and connecting means extending between the same, said connecting means being actuatable to cause said plates to tend to move toward each other for compressive action on the plug, means for moving said plug rectilinearly between open and closed positions in said chamber, said last named means being constructed and arranged to apply additional compressive stress to said plug in at least one position of the latter, when said means is moved rectilinearly past both fully closed and open positions of the plug, said plug comprising an elastometric member and a structural member, said structural member including means substantially encasing said elastometric member and slidingly engaging the walls of the chamber.