Bearing sealing and lubricating device

Claim 1

IN A DRILLING ASSEMBLY, A BIT BODY ADAPTED TO BE ATTACHED TO A DRILL PIPE STRING, SAID BODY HAVING A CUTTERSUPPORTING PIN, AND A ROTARY CUTTER CARRIED BY SAID PIN FOR ROTATION WITH RESPECT THERETO, SAID PIN AND CUTTER DEFINING BETWEEN THEMSELVES A SPACE IN WHICH LUBRICANT IS ADAPTED TO BE SITUATED, AND A SEALING RING CLOSING SAID SPACE, SAID BODY BEING FORMED WITH AN ELONGATED LUBRICANT-SUPPLY CHAMBER AND WITH AN ELONGATED LUBRICANT SUPPLY TWEEN SAID CHAMBER AND THE SPACE BETWEEN SAID PIN AND CUTTER, MEANS CARRIED BY SAID BODY AND COMMUNICATING WITH SAID CHAMBER FOR INITIALLY INTRODUCING LUBRICANT INTO THE LATTER AND THROUGH SAID PASSAGES INTO THE SPACE BETWEEN SAID PIN AND CUTTER UNDER A PREDETERMINED INITIAL PRESSURE, A PISTON SLIDABLE IN SAID CHAMBER AND A SPRING ACTING ON SAID PISTON FOR MAINTAINING THE PRESSURE OF THE LUBRICANT IN SAID SPACE, AND SAID BODY BEING FORMED WITH A BORE COMMUNICATING WITH ONE SIDE OF SAID PISTON AND WITH THE INTERIOR OF THE DRILL PIPE STRING FOR PROVIDING COMMUNICATION BETWEEN SAID ONE SIDE OF SAID PISTON AND THE DIFFERENTIAL PRESSURE OF THE DRILLING MUD IN THE DRILL PIPE STRING, WHEREBY THE LUBRICANT PRESSURE IN SAID SPACE IS MAINTAINED HIGHER THAN THE PRESSURE OUTSIDE OF THE DRILL.