Master cylinder

Claim 1

A MASTER CYLINDER FOR A HYDRAULIC BRAKE SYSTEM OF A MOTOR VEHICLE, THE MASTER CYLINDER HAVING A FLUID SUPPLY PORT IN A WALL OF THE CYLINDER IN COMMUNICATION WITH A SOURCE OF HYDRAULIC FLUID SUPPLY, A COMPRESSION CHAMBER IN THE CYLINDER, A PISTON SLIDABLE WITHIN THE CYLINDER HAVING SUFFICIENT CLEARANCE WITH THE CYLINDER WALL TO PERMIT READY PASSAGE OF FLUID BETWEEN THE PISTON AND THE CYLINDER, AN AXIAL CYLINDRICAL EXTENSION OF LESSER DIAMETER THAN THE PISTON ON AN END OF THE PISTON ADJACENT THE COMPRESSION CHAMBER WITH A SHOULDER FORMING A RADIAL WALL BETWEEN THE EXTENSION AND THE REMAINING PORTION OF THE PISTON, A RESILIENT COMBINATION VALVE AND SEALING RING CARRIED BY THE CYLINDRICAL EXTENSION OF THE PISTON WITH RADIAL CLEARANCE THEREBETWEEN, THE RING CONTACTING THE CYLINDER WALL TO SEAL THE PISTON BETWEEN THE COMPRESSION CHAMBER AND FLUID SUPPLY PORT AND CONTROL FLOW THROUGH THE FLUID SUPPLY PORT IN THE CYLINDER WALL ON A COMPRESSION STROKE OF THE PISTON, A DISHED MEMBER CARRIED BY THE PISTON ON A SECOND REDUCED DIAMETER EXTENSION OUTWARDLY OF THE CYLINDRICAL EXTENSION, A PISTON RETURN SPRING BIASING THE DISHED MEMBER TOWARD THE CYLINDRICAL EXTENSION WHILE LEAVING AN AXIAL SPACE BETWEEN THE DISHED MEMBER AND THE RING WHEN THE RING IS AGAINST THE RADIAL WALL, THE IMPROVEMENT COMPRISING A RESILIENT MEMBER INTERPOSED IN THE AXIAL SPACE BETWEEN THE DISHED MEMBER AND RESILIENT RING BIASING THE RESILIENT RING AGAINST THE RADIAL WALL.