Reciprocating hydraulic motor

Claim 1

A FLUID MOTOR COMPRISING: A HOUSING HAVING A CHAMBER THREIN, A MOVABLE PRESSURE WALL WITHIN SID CHAMBER AND SEALED ABOUT ITS PERIMETER TO SAID HOUSING, MEANS FOR SELECTIVELY ADMITTING PRESSURE FLUID TO THE CHAMBER SPACE AT ONE SIDE OF SAID WALL FOR MOVING THE LATTER IN ONE DIRECTION IN THE CHAMBER, SAID WALL HAVING A PASSGE THERETHROUGH FOR VENTING PRESSURE FLUID FROM SAID SPACE AND A VALVE SEAT ABOUT SAID PASSAGE, A VALVE CARRIED BY SAID WALL SO AS TO BE HELD IN SEATING ENGAGEMENT WITH SAID VALVE SEAT BY FLUID PRESSURE IN SAID SPACE, THEREBY TO CLOSE SAID PASSAGE, COACTING MEANS ON SAID HOUSING AND VALVE FOR UNSEATING THE LATTER FROM SAID VALVE SEAT TO OPEN SAID PASSAGE AND VENT SAID SPACE UPON MOVEMENT OF SAID WALL IN ONE DIRECTION IN SAID CHAMBER TO A GIVEN POSITION, SAID COACTING MEANS INCLUDING A RESILIENT MEANS WHICH IS DEFORMED DURING TERMINAL MOVEMENT OF SAID WALL TO SAID POSITION TO YIELDABLY URGED SAID VALVE FROM SAID VALVE SEAT AFTER INITIAL UNSEATING OF THE VALVE, MEANS FOR RETURNING SAID WALL IN THE OPPOSITE DIRECTION IN SAID CHAMBER, MEANS FOR RETAINING SAID VALVE UNSEATED DURING RETURN MOVEMENT OF SAID WALL, AND MEANS FOR RESEATING SAID VALVE ON SAID VALVE SEAT UPON RETURN MOVEMENT OF SAID WALL TO A GIVEN POSITION IN SAID CHAMBER.