Vehicle suspension systems

Claim 1

A DUAL RATE PNEUMATIC SPRING SUSPENSION SYSTEM FOR A VEHICLE COMPRISING, A FIRST CYLINDER AND A FIRST PISTON RECIPROCABLE THEREIN, A SECOND CYLINDER COAXIALLY DISPOSED WITHIN THE FIRST CYLINDER AND A SECOND PISTON RECIPROCABLE WITHIN THE SECOND CYLINDER, MEANS DEFINING FIRST AND SECOND GAS CHAMBERS WITHIN THE RESPECTIVE FIRST AND SECOND CYLINDERS TO PROVIDE PNEUMATIC SPRINGS, SAID SPRINGS RESISTING AXIAL MOVEMENT OF EACH PISTON INWARDLY OF EACH CYLINDER, PRESSURE TRANSMITTING MEANS INCLUDING A PASSAGEWAY FROM THE FIRST GAS CHAMBER TO AN OPEN END OF THE SECOND CYLINDER AND LIQUID IN THE PASSAGEWAY DIRECTLY EXPOSED TO THE GAS IN THE FIRST GAS CHAMBER FOR TRANSMITTING ALL PRESSURE FROM THE FIRST CHAMBER TO THE PISTON IN THE SECOND CHAMBER, AND A STOP FOR LIMITING AXIAL MOVEMENT OF THE SECOND PISTON OUTWARDLY OF THE SECOND CYLINDER AT PRESSURES IN THE FIRST CHAMBER BELOW THE PRECHARGE PRESSURE IN THE SECOND CHAMBER, WHEREIN MOVEMENT OF THE FIRST PISTON INWARDLY OF THE FIRST CYLINDER COMPRESSES THE GAS IN THE FIRST CHAMBER WITHOUT COMPRESSION OF THE GAS IN THE SECOND CHAMBER UNTIL THE PRESSURE IN THE FIRST CHAMBER EQUALS THE PRECHARGED PRESSURE IN THE SECOND CHAMBER AND CONTINUED INWARD MOVEMENT OF THE FIRST PISTON COMPRESSES THE GAS IN BOTH THE FIRST AND SECOND CHAMBERS AT A LOWERED SPRING RATE IN COMPARISON TO THAT WHICH WOULD BE PRODUCED BY THE FIRST CHAMBER ALONE, SAID MEANS DEFINING FIRST AND SECOND GAS CHAMBERS IN THE RESPECTIVE FIRST AND SECOND CYLINDERS INCLUDING A CAP DEFINING THE UPPER BOUNDARIES OF THE GAS CHAMBER, A SHROUD, CAP SCREW FASTENING MEANS EXTENDING THROUGH THE CAP AND DISPOSED BENEATH THE SHROUD, AND A CHARGING VALVE FOR THE FIRST GAS CHAMBER SO LOCATED IN THE CAP WITH RESPECT TO THE CAP SCREW FASTENING MEANS AND THE SHROUD AS TO REQUIRE REMOVAL OF THE VALVE AND VENTING OF THE PRESSURE IN SAID CHAMBER PRIOR TO REMOVAL OF THE CAP.