Seat suspension for a tractor and the like

Claim 1

IN A SEAT SUSPENSION ARRANGEMENT FOR A VEHICLE, IN COMBINATION: (A) SEAT PAN MEANS FOR CARRYING THE OPERATOR OF THE VEHICLE; (B) A CYLINDER ENCLOSING CAVITY; (C) A PISTON MOVABLE IN SAID CAVITY AND DIVIDING THE SAME INTO TWO COMPARTMENTS, (1) SAID CYLINDER AND SAID PISTON CONSTITUTING TWO MEMBERS OF A FLUID-PRESSURE OPERATED DEVICE; (D) FASTENING MEANS FOR FASTENING ONE OF SAID MEMBERS TO SAID VEHICLE; (E) MOTION TRANSMITTING MEANS CONNECTING SAID SEAT PAN MEANS TO THE OTHER ONE OF SAID MEMBERS FOR RELATIVE MOVEMENT OF SAID MEMBERS WHEN SAID SEAT PAN MEANS MOVES RELATIVE TO THE VEHICLE; (F) A SOURCE OF FLUID UNDER SUBSTANTIALLY CONSTANT PRESSURE COMMUNICATING WITH ONE OF SAID COMPARTMENTS, SAID SOURCE INCLUDING A PUMP, A DISCHARGE OPENING, AND TO SAID PUMP AND HAVING A DISCHARGE OPENING, AND CHECK VALVE MEANS INTERPOSED IN SAID CONDUIT BETWEEN SAID PUMP AND SAID OPENING AND RESPONSIVE TO A PREDETERMINED PRESSURE FOR OPENING SAID CONDUIT TO FLOW FROM SAID PUMP TO SAID OPENING, SAID ONE COMPARTMENT COMMUNICATING WITH A PORTION OF SAID CONDUIT INTERMEDIATE SAID PUMP AND SAID CHECK VALVE MEANS; (G) A GAS CUSHION UNDER PRESSURE; AND (H) PRESSURE TRANSMITTING MEANS FOR TRANSMITTING THE PRESSURE OF SAID CUSHION TO SAID PISTON IN THE OTHER ONE OF SAID COMPARTMENTS.