Hydro-pneumatic suspension units for vehicles

Claim 1

A HYDRO-PNEUMATIC SUSPENSION UNIT FOR A VEHICLE ADAPTED TO ACT AS A SELF-ADJUSTING STRUT COMPRISING A CYLINDER HAVING A FIRST END AND A SECOND END, A PRESSURE CHAMBER COMMUNICATING WITH ONE END OF THE CYLINDER AND CONTAINING A GAS AND A LIQUID, A PISTON MEMBER WORKING IN THE CYLINDER, A PISTON ROD MEMBER AT ONE END CARRYING SAID PISTON AND AT ITS OTHER END PROJECTING FROM THE OTHER END OF SAID CYLINDER, A WORKING CHAMBER IN SAID CYLINDER BETWEEN SAID ONE END AND SAID PISTON, A PUMPING CHAMBER IN SAID CYLINDER BETWEEN SAID PISTON AND SAID OTHER END OF SAID CYLINDER, A FIRST ONE-WAY VALVE IN SAID PISTON TO ALLOW LIQUID FLOW FROM SAID PUMPING CHAMBER INTO SAID WORKING CHAMBER, A RESERVOIR FOR LIQUID, PASSAGE MEANS CONNECTING SAID RESERVOIR TO SAID PUMPING CHAMBER, A SECOND ONE-WAY VALVE ASSOCIATED WITH SAID PASSAGE MEANS TO ALLOW LIQUID FLOW FROM SAID RESERVOIR INTO SAID PUMPING CHAMBER, OUTLET MEANS FROM SAID WORKING CHAMBER LOCATED AT SAID ONE END OF THE CYLINDER, MEANS DEFINING A PASSAGE CONNECTING SAID OUTLET MEANS AND SAID RESERVOIR DIRECTLY, A VALVE CO-OPERATING WITH SAID OUTLET MEANS, SPRING MEANS ENGAGING SAID VALVE TO BIAS SAID VALVE TO A POSITION CLOSING SAID OUTLET MEANS WHEREBY SAID VALVE MAINTAINS SAID OUTLET MEANS CLOSED WHILE SAID PISTON OCCUPIES A FIRST RANGE OF POSITIONS RELATIVE TO SAID CYLINDER, AND MECHANICAL MEANS CO-OPERATING WITH SAID PISTON AND SAID VALVE MOVE SAID VALVE POSITIVELY TO OPEN SAID OUTLET MEANS WHEN SAID PISTON MOVES INTO A SECOND RANGE OF POSITIONS RELATIVE TO SAID CYLINDER, THE POSITION OF THE PISTON IN SAID FIRST RANGE, WHEN THE PISTON IS ABOUT TO ENTER SAID SECOND RANGE, CORRESPONDING TO THE PREFERRED ADJUSTED LENGTH OF THE UNIT.