Cruciform rubber support ring for plastic cap rings

Claim 1

A SEAL FOR PREVENTING THE LEAKAGE OF FLUID BETWEEN TWO RELATIVELY MOVABLE MEMBERS HAVING MATING CYLINDRIC SURFACES WITH WORKING CLEARANCE THEREBETEEN, ONE OF SAID SURFACES HAVING AN ANNULAR GROOVE OF SUBSTANTIALLY RECTANGULAR CROSS-SECTION CONFRONTING THE OTHER SURFACE, IN WHICH GROOVE THE SEAL IS SEATED, SAID SEAL COMPRISING; A CONTINUOUS ANNULAR CAP RING OF TOUGH BUT FLEXIBLE MATERIAL HAVING A LOW COEFFICIENT OF FRICTION WITH RESPECT TO THE MATERIAL OF SAID OTHER SURFACE; SAID CAP RING HAVING A BASE COMPRISING A THIN SHELL WITH CYLINDRIC INNER AND OUTER WALLS AND A PAIR OF RADIALLY PROJECTING FLANGES AS ITS ENDS COOPERATING TO FORM A CHANNEL, SAID CAP RING INCLUDING THE FLANGES HAVING AN AXIAL LENGTH SUBSTANTIALLY THE SAME AS THAT OF THE GROOVE AND BEING RECEIVABLE THEREIN WITH SAID FLANGES EXTENDING TOARD THE BOTTOM OF THE GROOVE AND WITH ITS OUTER SURFACE SLIDABLY ENGAGEABLE WITH THE SURFACE OF THE OTHER RELATIVELY MOVABLE MEMBER, AND A RESILIENT, DEFORMABLE, RUBBER-LIKE, ANNULAR PRESSURE RING SEATED IN SAID GROOVE AND NESTED WITHIN THE CHANNEL OF SAID CAP RING FOR URGING THE CAP RING INTO SEALING ENGAGEMENT WITH THE SURFACE WHICH IT CONTACTS; SAID PRSSURE RING BEING CRUIFORM IN CROSS-SECTION WITH ONE PAIR OF ARMS EXTENDING RADIALLY AND ONE PAIR OF ARMS EXTENDING AXIALLY TO PROVIDE AN AXIALLY CENTRAL BODY PORTION EXTENDING FROM THE BOTTOM OF THE GROOVE TO THE ADJACENT WALL OF THE CAP RING AND RESILIENTLY SUPPORTING THE AXIALLY CENTRAL SECTION OF SAID CAP RING THROUGHOUT A SUBSTANTIAL PORTION OF ITS LENGTH; THE AXIALLY EXTENDING ARMS BEING SPACED GENERALLY CENTRALLY BETWEEN THE INNER AND OUTER WALLS OF SAID PRESSURE RING TO CONSTITUTE ANNULAR BOSSES, EACH PROVIDING INNER AND OUTER ANNULAR RECESSES TO FACILITATE INSTALLATION OF SAID SEAL IN AN ASSEMBLY OF RELATIVELY MOVABLE MEMBERS.