Hydrostatic drive

A valve device for a hydraulic drive, the valve device comprising:

• a pair of first valves, each first valve located in respective first and second load lines, said first and second load lines are connectable to a fluid power displacement unit and a fluid outlet displacement unit, said pair of first valves being configured to selectively open and close their respective load lines;
• a pair of second valves with non-return functions;
• a pair of third valves with proportional functions;
• a pair of fourth valves with proportional pressure relief functions;
• said second valves, said third valves, and said fourth valves being connected to and positioned between said first and second load lines by connecting lines;
• and
• an accumulator being disposed in an accumulator circuit, said accumulator circuit being subdivided into a low-pressure side and a high-pressure side, said pairs of first, second, third, and fourth valves being connected to said accumulator circuit;
• and
• one of said pair of second valves is connected to and positioned between said first load line and said low-pressure side of the accumulator circuit, the other one of the said pair of second valves being connected to and positioned between said second load line and said low-pressure side of the accumulator circuit.

A hydrostatic drive, comprising:

• a fluid power displacement unit having an adjustable volumetric flow and being coupled to a power supply;
• a fluid output displacement unit having an adjustable volumetric flow and being coupled to an output drive, said power and output displacement units being connected to one another in a closed loop circuit by first and second load lines connected to respective input and output sides of said power and output displacement units;
• an accumulator disposed in an accumulator circuit that is connected to said power and output displacement units, said accumulator circuit being subdivided into a low-pressure side and a high-pressure side;
• a valve system being coupled to and controlling said power and output displacement units and said accumulator circuit, said valve system being connected to said first and second load lines and including first and second directional valves in said first and second load lines, respectively;
• first and second non-return valves connected to one another and also connected to and disposed between said first and second load lines;
• first and second proportional valves connected to one another, said first and second proportional valves being connected to and disposed between said first and second load lines, being in parallel to said first and second non-return valves, and being connected to said high-pressure side of said accumulator circuit at a connection between said first and second proportional valves;
• and
• first and second proportional relief valves being connected to one another, said first and second proportional relief valves being connected to said first and second load lines at locations between said first and second directional valves and said first and second proportional valves, and being fluidly in parallel to said first and second proportional valves.

A hydrostatic drive comprising:

• a first fluid displacement unit having an adjustable volumetric flow and being coupled to a power supply;
• a second fluid displacement unit having an adjustable volumetric flow and being coupled to an output drive, said first displacement unit being connected to said second displacement unit in a closed loop circuit by first and second load lines connected to respective input and output sides of said first and second displacement units;
• an accumulator disposed in an accumulator circuit being connected to said first and second displacement units, said accumulator circuit being subdivided into a low-pressure side and a high-pressure side;
• a valve system configured to control said first and second displacement units and said accumulator circuit, said valve system being connected to said first and second load lines;
• a first valve with a non-return function being connected to and positioned between said first load line and said low-pressure side of said accumulator circuit;
• a second valve with a non-return function being connected to and positioned between said second load line and said low-pressure side of said accumulator circuit;
• a permanent fluid volume supply being connected to said second displacement unit and being connected to said low-pressure side of said accumulator circuit between said first and second valves with non-return functions, said permanent fluid supply being connected to a feed line at an inlet of said permanent fluid supply and being connected to a tank at an outlet of said permanent fluid supply, said feed line being permanently connected to said low-pressure side of said accumulator circuit via a connection point;
• a non-return valve being disposed in said feed line between said connection point and said inlet;
• and
• a pressure relief valve being disposed in said feed line between said connection point and said outlet.

A hydrostatic drive comprising:

• a first fluid displacement unit having an adjustable volumetric flow and being coupled to a power supply;
• a second fluid displacement unit having an adjustable volumetric flow and being coupled to an output drive, said first displacement unit being connected to said second displacement unit in a closed loop circuit by first and second load lines connected to respective input and output sides of said first and second displacement units;
• an accumulator disposed in an accumulator circuit being connected to said first and second displacement units, said accumulator circuit being subdivided into a low-pressure side and a high-pressure side;
• a valve system configured to control said first and second displacement units and said accumulator circuit, said valve system being connected to said first and second load lines;
• a first valve with a non-return function being connected to and positioned between said first load line and said low-pressure side of said accumulator circuit;
• a second valve with a non-return function being connected to and positioned between said second load line and said low-pressure side of said accumulator circuit;
• and
• a first proportional valve and a second proportional valve with proportional functions being connected to said first and second load lines, respectively, said high-pressure side of said accumulator circuit being connected at a connection located between said first and second proportional valves.