Load balancing system for hydraulic jack

Claim 1

IN AN ENGINE DRIVEN VEHICLE HAVING A MACHINE COMPONENT ACTUATED BY A HYDRAULIC JACK, APPARATUS FOR BALANCING AT LEAST A PORTION OF THE WEIGHT OF SAID MACHINE COMPONENT, SAID APPARATUS COMPROSING IN COMBINATION, A HYDRAULIC JACK HAVING THE USUAL CYLINDER, PISTON AND ROD, SAID ROD HAVING A BORE OPENING AT ITS INNER END, A TUBE HAVING A FIRST END FIXEDLY SECURED TO AND EXTENDING THROUGH THE HEAD END OF SAID CYLINDER, SAID TUBE HAVING A SECOND END PORTION EXTENDING INTO SAID ROD BORE, A STATIONARY WALL MEMBER FIXEDLY SECURED TO THE TUBE ANS SLIDABLY FITTING THE ROD BORE TO DEFINE ONE END OF AN INTERNAL EXPANSIBLE CHAMBER WITHIN SAID ROD BORE, HYDRAULIC FLUID MEANS FOR EXTENDING AND RETRACTING SAID JACK, AND A HYDRAULIC CIRCUIT FOR DIRECTING FLUID FROM A PRESSURE FLUID RESERVOIR THROUGH SAID TUBE AND INTO SAID EXPANSIBLE CHAMBER, SAID HYDRAULIC CIRCUIT COMPRISING AN ACCUMULATOR CHARGEABLE TO A PREDETERMINED PRESSURE BY EXTENDING AND RETRACTING SAID JACK, A PRESSURE CONTROL VALVE LOCATED IN SAID HYDRAULIC CIRCUIT BETWEEN SAID ACCUMULATOR AND SAID EXPANDIBLE CHAMBER FOR PREVENTING FLUID FLOW BETWEEN SAID EXPANDIBLE CHAMBER AND SAID ACCUMULATOR WHEN THE PRESSURE IN THE HYDRAULIC CIRCUIT DROPS BELOW SAID PREDETERMINED PRESSURE, CHECK VALVE MEANS LOCATED IN SAID HYDRAULIC CIRCUIT BETWEEN SAID EXPANSIBLE CHAMBER AND SAID RESERVIOR TO COMMUNICATE PRESSURE FLUID FROM SAID RESERVIOR TO SAID EXPANSIBLE CHAMBER WHEN THE PRESSURE IN THE HYDRAULIC CIRCUIT DROPS BELOW SAID PREDETERMINED PRESSURE, WHEREBY DURING NORMAL OPERATION SAID EXPANSIBLE CHAMBER IS SUPPLIED WITH PRESSURE FLUID WHICH IS SUFFICIENT TO BALANCE OR OFFSET AT LEAST A PORTION OF THE WEIGHT OF SAID MACHINE COMPONENT, AND A SAFETY VALVE SITUATED BETWEEN SAID PRESSURE FLUID RESERVOIR AND SAID ACCUMULATOR, MEANS RESPONSIVE TO OPERATION OF SAID ENGINE TO NORMALLY CLOSE SAID SAFETY VALVE AND PREVENT FLUIDFLOW FROM SAID ACCUMULATOR TO SAID RESERVOIR, SAID SAFETY VALUE FURTHER HAVING MEANS OPERABLE TO OPEN SAID SAFETY VALUE TO ALLOW FLUID TO FLOW FROM SAID ACCUMULATOR TO SAID RESERVOIR WHEN SAID ENGINE IS SHUT DOWN.