Means for saving energy in a hydraulic circuit

Claim 1

In a hydraulic circuit in which working fluid is supplied to activate at least one function, including a function control valve communicating with the working fluid for controlling the supply of working fluid to a respective function, the improvement comprising: a free circulation valve connected into the hydraulic circuit communicating with the working fluid; a plurality of solenoid means for opening and closing said free circulation and function control valves, each solenoid means being associated with a respective one of said valves; said solenoid means associated with said free circulation valve functioning to close said free circulation valve when current thereto is interrupted; solenoid control switching means for actuating selected ones of said functions by opening said solenoid means associated therewith, for interrupting current to said solenoid means associated with said free circulation valve thereby closing the latter to prevent working fluid from passing therethrough when at least one of said function control valves is open and for supplying current to said solenoid means associated with said free circulation valve thereby opening the same to permit working fluid to pass therethrough only when all of said function control valves are closed; and wherein said hydraulic circuit further includes a pressure regulating valve communicating with the working fluid and wherein said free circulation valve is connected in said hydraulic circuit in parallel with said pressure regulating valve to permit the working fluid to bypass said pressure regulating valve when said free circulation valve is open.