Dual lip rod wiping seal

A piston and cylinder assembly comprising:

• a cylinder having an end wall with an axial opening formed therein;
• a piston having a rod reciprocably received in the opening in said end wall;
• a wiping seal retention groove formed in said end wall having a top wall, a bottom wall, and an annular side wall extending therebetween;
• a one-piece self supporting sealing member having a main body portion of substantially rectangular cross section received in said groove;
• said main body portion having top and bottom end walls in opposed relationship with the top and bottom end walls, respectively, of said groove;
• said main body portion having inner and outer annular side walls with said outer annular side wall in opposed relationship with the side wall of said groove;
• first and second endless lips projecting from said top end wall into the axial opening formed in the end wall of said cylinder;
• each of said lips having an inner end joined integrally to said top end wall and projecting therefrom to an outer free end with the respective free ends spaced radially from each other;
• said first lip constituting a rod engaging lip and having an inner side surface engaging the surface of said rod and projecting from said top end wall axially and radially inwardly in the unstressed condition thereof so as to apply sealing pressure to the surface of said piston rod;
• said second lip constituting a cylinder engaging lip and having an outer side surface extending between the ends thereof;
• said outer side surface of said second lip having an inner end joined to said top end wall at a location spaced radially inwardly from said outer annular side wall of said body, said outer side surface projecting axially and radially outwardly from said top end wall in the unstressed condition thereof so as to apply sealing pressure to the wall of said opening in said end wall of said cylinder;
• said sealing lips being resiliently flexed inwardly toward each other when said rod is inserted in the opening in said end wall to cause said sealing lips to apply sealing pressure to the surfaces of the rod and opening;
• the portion of said one end wall extending radially outwardly of said second lip, said outer side wall, and said other end wall constituting mounting groove engaging surfaces of said body received in said groove to support said body in said cylinder;
• a clearance being defined between the respective outer side wall of said main body portion and groove as well as a clearance being defined between said inner side wall of said main body portion and said rod to accommodate transverse movement of said rod when said sealing member is installed in said cylinder.