Seal for steering assist fluid motor

In a fluid motor in a rack and pinion motor vehicle steering gear including a rack bar and a cylinder tube around said rack bar, the combination comprising:

• an annular bulkhead around said rack bar in an outboard end of said cylinder tube having an annular end facing a working chamber of said fluid motor,
• a bearing means between said bulkhead and said rack bar,
• a retaining means operative to prevent dislodgment of said bulkhead from said outboard end of said cylinder tube by fluid pressure in said working chamber of said fluid motor,
• a seal ring in said working chamber of said fluid motor adjacent said annular end of said bulkhead including an elastomeric body having a cylindrical outer surface compressed against said cylinder tube and an inner lip compressed against said rack bar,
• a coupling means operative to couple said seal ring to said bulkhead for unitary handling and transport outside of said cylinder tube and to uncouple said seal ring from said bulkhead within said cylinder tube to isolate said seal ring from relative movement between said bulkhead and said cylinder tube induced by movement of said rack bar relative to said cylinder tube transferred to said bulkhead through said bearing means thereby to prevent wear of said seal ring attributable to relative movement between said bulkhead and said cylinder tube,
• wherein said seal ring comprises a metal reinforcement having a cylindrical segment and an annular segment in a plane perpendicular to said cylindrical segment,
• an elastomeric body molded around said metal reinforcement with said cylindrical outer surface of said seal ring and said inner lip each integral with said elastomeric body concentric with said cylindrical segment of said metal reinforcement, and
• an annular polymeric insert on said elastomeric body between said inner lip and said bulkhead reinforcing said inner lip against being squeezed by fluid pressure in said working chamber of said fluid motor between said bulkhead and said rack bar, and
• a cylindrical shoulder on said bulkhead perpendicular to said annular end of said bulkhead,
• an annular lobe on said elastomeric body of said seal ring outboard of and longitudinally overlapping said cylindrical shoulder on said bulkhead,
• an annular groove in said cylindrical shoulder facing said annular lobe on said elastomeric body of said seal ring, and
• a flexible annular lip on said lobe on said elastomeric body of said seal ring stretched over said cylindrical shoulder on said bulkhead and seated in said annular groove in said cylindrical shoulder with predetermined clearance between said flexible annular lip and said annular groove so that said seal ring is loosely coupled to said bulkhead for unitary handling and transport.