Seal assembly having a plastic annular sealing member with an integral sealing lip

A track joint (12) comprising:

• first and second pivotally connected overlapping links (14, 16) coaxially mounted along a pivot axis (18) to a concentrically disposed track pin (20) and associated cylindrical bushing (22) respectively, the bushing (22) having a radially extending, axially inwardly facing end face (34), a counterbore (26) disposed in the first link (14) and defined by a radially extending, axially outwardly facing end face (28) and a cylindrical surface (30);
• an annular spacer member (24) surrounding the pin (20) and extending between the end faces (28, 34) of the counterbore (26) and the bushing (22);
• and a seal assembly (10) disposed in the counterbore (26) for retaining lubricant in the track joint (12) and for preventing the ingress of contaminants therein, the seal assembly (10) including an annular polymeric plastic sealing member (36) having an integral sealing lip (38), load means (42) borne by the first link (14) for urging the sealing lip (38) into sealing engagement with the bushing end face (34), said sealing member (36) having a dry coefficient of dynamic friction on lapped hardened steel in the range of approximately 0.05 to approximately 0.35 and a load/velocity relationship (PV) in the range of approximately 70.0 (2,000) to approximately 1576.0 (45,000).

A seal assembly (10) positioned between first and second relatively movable members (14, 22) for sealing therebetween and cooperating therewith in defining a lubricant holding chamber (35) comprising:

• an annular sealing member (36) having an integral sealing lip (38) for retaining lubricant in the chamber (35) and for preventing the ingress of contaminants therein, the annular sealing member (36) being of a thermoplastic resin selected from the group consisting of hexamethyleneadipamide containing approximately 18% polytetrafluoroethylene (PTFE) and approximately 2% silicone oil and ultra-high molecular weight polyethylene (UHMW-PE);
• and
• load means (42) borne by the first member (14) for urging the sealing lip (38) into sealing engagement with the second member (22).