Piston-and-cylinder arrangement

Claim 1

IN A PISTON-AND-CYLINDER ARRANGEMENT, IN COMBINATION, A CYLINDER HAVING AN INNER WALL; A PISTON ASSEMBLY AXIALLY RECIPROCABLE WITHIN SAID CYLINDER AND COMPRISING FIRST AND SECOND RELATIVELY MOVABLE PISTONS JOINTLY DISPLACEABLE WITHIN SAID CYLINDER, SAID FIRST AND SECOND PISTONS BEING PROVIDED WITH INTERFITTING MEANS FORMING BETWEEN THEM A CLOSED CENTRAL COMPARTMENT OF VARIABLE VOLUME CONTAINING A GAS AND RESPECTIVE JUXTAPOSED HIGHPRESSURE SURFACES DEFINING AN ANNULAR RECESS OF VARIABLE VOLUME OUTWARDLY OF SAID COMPARTMENT CONFRONTING SAID WALL OF SAID CYLINDER, SAID RECESS EXTENDING GENERALLY TRANSVERSELY TO THE AXIS OF SAID CYLINDER, EACH OF SAID PISTONS HAVING A RESPECTIVE LOW-PRESSURE SURFACE HAVING A SURFACE AREA IN EXCESS OF THAT OF THE RESPECTIVE HIGHPRESSURE SURFACE EXPOSED TO FLUID PRESSURE IN ONE OF SAID CHAMBERS, SAID ASSEMBLY SUBDIVIDING SAID CYLINDER INTO A PAIR OF WORKING CHAMBERS ISOLATED FROM SAID COMPARTMENTS; AND A SEALING ELEMENT DEFORMABLE UNDER PRESSURE IN SAID RECESS AND DISPOSED BETWEEN SAID HIGH-PRESSURE SURFACE FOR COMPRESSION THEREBY RADIALLY OUTWARDLY INTO ENGAGEMENT WITH SAID WALL UPON INTRODUCTION OF FLUID UNDER PRESSURE INTO AT LEAST ONE OF SAID CHAMBERS AGAINST ONE OF SAID LOW-PRESSURE SURFACES TO DISPLACE SAID ASSEMBLY WITHIN SAID CYLINDER WHILE CONCURRENTLY EXERTING PRESSURE UPON ONE OF SAID PISTONS IN THE DIRECTION OF THE OTHER OF SAID PISTONS, SAID INTERFITTING MEANS INCLUDING A MALE FORMATION ON ONE OF SAID PISTONS DISPOSED ON A HIGH-PRESSURE SIDE OF SAID CYLINDER AND A FEMALE FORMATION COMPLEMENTARILY RECEIVING SAID MALE FORMATION FORMED IN THE OTHER OF SAID PISTONS, SAID MALE AND FEMALE FORMATIONS BEING AXIALLY ALIGNED, SAID RECESS BEING OF TRUNCATED CONICAL CONFIGURATION AND DIVERGING FROM SAID AXIS IN THE DIRECTION OF SAID LOW-PRESSURE SIDE OF SAID CYLINDER.