Pressure equalizing means for a double cardan joint centering device

Claim 1

A UNIVERSAL JOINT ASSEMBLY COMPRISING, A PAIR OF CONNECTED UNIVERSAL JOINTS, CENTERING MEANS FOR SAID JOINT COMPRISING COOPERATING MEMBERS ONE HAVING A SOCKET MEANS AND THE OTHER HAVING A STEM EXTENDING AXIALLY INTO SAID SOCKET MEANS, A BALL MEMBER ROTATABLY AND AXIALLY MOVABLE ON SAID STEM AND ENGAGING SAID SOCKET MEANS, MEANS DEFINING A RESEVOIR INWARDLY FROM THE ENGAGEMENT OF SAID BALL MEMBER AND SOCKET MEANS, A SEAL ABUTTING SAID SOCKET MEANS AND SAID BALL MEMBER OUTWARDLY FROM SAID RESERVOIR TO PREVENT THE ESCAPE OF LUBRICANT THEREFROM, SAID SOCKET MEANS HAVING A PLURALITY OF AXIALLY EXTENDING GROOVES ON THE INNER SURFACE THEREOF EXTENDING FROM THE AREA OF SAID SEAL TO THE OPPOSITE SIDE OF THE ENGAGEMENT BETWEEN SAID SOCKET MEANS AND SAID BALL MEMBER, AND SAID SOCKET MEANS HAVING A CIRCUMFERENTIALLY EXTENDING GROOVE ON THE INNER SURFACE THEREOF IN THE AREA OF THE ENGAGEMENT BETWEEN SAID SOCKET MEANS AND SAID BALL MEMBER AND CONFLUENT WITH SAID AXIAL GROOVES, WHEREBY THE PRESSURE IN THE AREA OF SAID SEAL AND THE PRESSURE IN THE RESEVOIR ARE MAINTAINED SUBSTANTIALLY EQUAL.