Abstract: An orientation-independent electro-hydraulic actuator that includes a housing having an interior space forming a fluid reservoir, a pump connected to the housing, an electric motor drivingly coupled to the pump; and a piston-cylinder assembly having a piston axially movable within a cylinder. The cylinder is in fluid communication with the pump to effect movement of the piston in response to fluid flow between the cylinder and the fluid reservoir. The pump has one or more inlet/outlet ports communicating with a volumetric centroid region of the fluid reservoir. The fluid reservoir includes a volume of hydraulic fluid such that when the piston is fully extended, the volume of fluid in the reservoir is at a minimum and at least one of the inlet/outlet ports is submerged in hydraulic fluid.

Abstract: An improvement to the component based hydraulic systems is an integrated electro-hydraulic actuator (EHA) that contains all components necessary to achieve power up, gravity return actuation of a lift mechanism such as the forks of a pallet truck. Further, improvements to known power-up, gravity-down component-based hydraulic circuits are described herein. The improvements provide for power up, gravity return functionality with fewer components as compared known systems. Finally, a method for controlling the EHA and/or hydraulic circuits described above is detailed herein and provides a user with maximum control of a lift mechanism during lower or “down mode,” but also provides for the least amount of energy consumption by the actuator.

Abstract: An orientation-independent electro-hydraulic actuator that includes a housing having an interior space forming a fluid reservoir, a pump connected to the housing, an electric motor drivingly coupled to the pump; and a piston-cylinder assembly having a piston axially movable within a cylinder. The cylinder is in fluid communication with the pump to effect movement of the piston in response to fluid flow between the cylinder and the fluid reservoir. The pump has one or more inlet/outlet ports communicating with a volumetric centroid region of the fluid reservoir. The fluid reservoir includes a volume of hydraulic fluid such that when the piston is fully extended, the volume of fluid in the reservoir is at a minimum and at least one of the inlet/outlet ports is submerged in hydraulic fluid.