Self-leveling hydropneumatic suspension unit

Claim 1

A SELF-LEVELING HYDRO-PNEUMATIC SUSPENSION UNIT COMPRISING, IN COMBINATION: (A) A CYLINDER MEMBER HAVING AN AXIS AND FORMED WITH A CAVITY THEREIN; (B) A PISTON MEMBER AXIALLY MOVABLE IN SAID CAVITY AND AXIALLY DEFINING A CHAMBER IN A PORTION OF THE CAVITY, SAID CHAMBER EXPANDING AND CONTRACTING DURING THE AXIAL MOVEMENT OF THE PISTON MEMBER OUTWARD AND INWARD OF SAID CHAMBER; (C) TWO FASTENING MEANS FOR FASTENING SAID MEMBERS RESPECTIVELY TO A SUSPENDED MASS AND TO A STRUCTURE FROM WHICH SAID MASS IS TO BE SUSPENDED; (D) A LIQUID SUSTANTIALLY FILLING SAID CHAMBER; (E) YIELDABLY RESILIENT MEANS FOR MAINTAINING SAID LIQUID IN THE CHAMBER UNDER A PRESSURE SUBSTANTIALLY GREATER THAN ATMOSHPERIC PRESSURE; (F) AN ADDITIONAL SUPPLY OF SAID LIQUID; (G) PUMP MEANS FOR PUMPING LIQUID FROM SAID SUPPLY TO SAID CHAMBER IN RESPONSE TO AXIAL RECIPROCATING MOVEMENT OF SAID PISTON MEMBER IN A PREDETERMINED AXIAL PORTION OF SAID CYLINDER MEMBER; (H) BY-PASS MEANS RESPONSIVE TO A POSITION OF SAID PISTON MEMBER OUTWARDLY SPACED FROM SAID PRETERMINED PORTION OF SAID CYLINDER MEMBER FOR CONNECTING SAID CHAMBER TO SAID SUPPLY; AND (I) PUMP INACTIVATING MEANS RESPONSIVE TO A PREDETERMIND PRESSURE IN SAID CHAMBER FOR INACTIVATING SAID PUMP MEANS.