Abstract: A hydraulic cylinder in which the cylinder head contains a motor-driven fluid pump, fluid reservoir, and a main control valve for the cylinder. The cylinder includes a transfer tube that extends through the center of the cylinder's piston and terminates within a hollow ported section of a piston rod. The cylinder head can additionally include two electrically-actuated pilot valves and two pilot-operated check valves. The pilot-operated check valves include structure that, in combination with passages in the cylinder head, cause both pilot-operated check valves to open when pressurized fluid is being directed to one of the pilot-operated check valves by the main control valve.

Abstract: A hydraulic cylinder in which the cylinder head contains the main control valve for the cylinder. In one fluid path from the main control valve to an area located on one side of the cylinder's piston, fluid is directed through a transfer tube that extends through the center of the piston and terminates within a hollow ported section of the piston rod. The cylinder head can additionally include two electrically-actuated pilot valves and two pilot-operated check valves. The pilot-operated check valves are located in different passages that extend to areas located on opposite sides of the piston. The pilot-operated check valves include structure that, in combination with passages in the cylinder head, cause both pilot-operated check valves to open when pressurized fluid is being directed to one of the pilot-operated check valves by the main control valve. In the preferred embodiment, electrical wiring to the cylinder head travels through one of the fluid hoses connected to the cylinder.

Abstract: A hydraulic cylinder in which the cylinder head contains a motor-driven fluid pump, fluid reservoir, and a main control valve for the cylinder. The cylinder includes a transfer tube that extends through the center of the cylinder's piston and terminates within a hollow ported section of a piston rod. The cylinder head can additionally include two electrically-actuated pilot valves and two pilot-operated check valves. The pilot-operated check valves include structure that, in combination with passages in the cylinder head, cause both pilot-operated check valves to open when pressurized fluid is being directed to one of the pilot-operated check valves by the main control valve.

Abstract: A hydraulic cylinder in which the cylinder head contains the main control valve for the cylinder. In one fluid path from the main control valve to an area located on one side of the cylinder's piston, fluid is directed through a transfer tube that extends through the center of the piston and terminates within a hollow ported section of the piston rod. The cylinder head can additionally include two electrically-actuated pilot valves and two pilot-operated check valves. The pilot-operated check valves are located in different passages that extend to areas located on opposite sides of the piston. The pilot-operated check valves include structure that, in combination with passages in the cylinder head, cause both pilot-operated check valves to open when pressurized fluid is being directed to one of the pilot-operated check valves by the main control valve. In the preferred embodiment, electrical wiring to the cylinder head travels through one of the fluid hoses connected to the cylinder.

Abstract: A hydraulic cylinder in which the cylinder head contains a motor-driven fluid pump, fluid reservoir, and a main control valve for the cylinder. The cylinder includes a transfer tube that extends through the center of the cylinder's piston and terminates within a hollow ported section of a piston rod. The cylinder head can additionally include two electrically-actuated pilot valves and two pilot-operated check valves. The pilot-operated check valves include structure that, in combination with passages in the cylinder head, cause both pilot-operated check valves to open when pressurized fluid is being directed to one of the pilot-operated check valves by the main control valve.

Abstract: A direct-drive, backlash-free servovalve in which the tip of an electric motor continually engages opposite sides of a receiving groove in the valve spool. The tip has a trapezoidal cross-section and tapers downwardly toward its extreme end. Rotation of the tip causes a translation of the valve spool, and can only progress until a side of the tip jams against one of the groove's sidewalls.

Abstract: A method and apparatus for measuring and sorting component parts of an assembly includes a single station wherein parts are continuously fed, precisely measured, sorted by measurement, and then transported. For measuring the parts a contact member is mounted for extremely precise and controlled movements by a voice coil motor. The contact member is initially referenced with respect to a datum and is then placed into contact with the part. An optical encoder senses the position of the contact member to enable a determination of the critical dimension. The contact member includes a removable portion that is shaped to measure a desired critical dimension. This may include the height, inside diameter, outside diameter, roundness, or location of a feature of the part.