Servomotor with normally stationary valve structure

Claim 1

IN A FLUID PRESSURE SERVOMOTOR: A HOUSING HAVING A GENERALLY AXIALLY EXTENDING CHAMBER HAVING A GENERALLY FIXED END WALL; A FIRST MOVABLE WALL AXIALLY SPACED APART FROM SAID END WALL AND FORMING A FIRST LOW PRESSURE CHAMBER THEREBETWEEN; A SECOND MOVABLE WALL AXIALLY SPACED ON THE OPPOSITE SIDE OF SAID FIRST MOVABLE WALL FROM SAID END WALL AND FORMING A POWER CHAMBER BETWEEN SAID MOVABLE WALLS, SAID FIRST MOVABLE WALL BEING MOVABLE TOWARD SAID SECOND MOVABLE WALL; A SECOND LOW PRESSURE CHAMBER ON THE SIDE OF SAID SECOND MOVABLE WALL OPPOSITE SAID FIRST MOVABLE WALL; A TUBULAR PROJECTION ON SAID FIRST MOVABLE WALL PROJECTING THROUGH SAID FIXED END WALL AND MOVABLY SEALED WITH RESPECT THERETO; MEANS FOR COMMUNICATING A SOURCE OF LOW PRESSURE TO SAID FIRST LOW PRESSURE CHAMBER; STOP MEANS FOR LIMITING MOVEMENT OF SAID FIRST MOVABLE WALL TOWARD SAID END WALL; CONTROL VALVE MEANS MOUNTED ON AND CARRIED BY SAID FIRST MOVABLE WALL, SAID CONTROL VALVE MEANS HAVING A CONTROL MEMBER WHICH WHEN MOVED TOWARD SAID SECOND MOVABLE WALL COMMUNICATES HIGH PRESSURE TO SAID POWER CHAMBER; AND ABUTMENT MEANS OPERATIVELY POSITIONED BETWEEN SAID CONTROL MEMBER AND SAID SECOND MOVABLE WALL FOR DRIVING SAID SECOND MOVABLE WALL WHEN INSUFFICIENT PRESSURE DIFFERENTIAL EXISTS ACROSS SAID FIRST MOVABLE WALL TO HOLD IT AGAINST SAID STOP MEANS; WHEREBY SAID FIRST MOVABLE WALL REMAINS STATIONARY WHEN HIGH PRESSURE IS ADMITTED TO SAID POWER CHAMBER AND WHEREBY SAID CONTROL MEMBER PHYSICALLY ACTUATES SAID SECOND MOVABLE WALL WHEN SUBSTANTIALLY NO PRESSURE DIFFERENTIAL EXISTS ACROSS SAID FIRST MOVABLE WALL.