Abstract: A float positioning assembly for servo actuated proportional control valves which increases the percentage of available pilot pressure for use during normal "raise" and "lower" modes of operation thereby saving energy. The float positioning assembly is connected to one end of a proportional control valve housing in axial alignment with a slidable valve spool. It includes a differential piston which is positioned between a centering spring assembly and an end member. The centering spring assembly includes a support member which is fixed at one end to the axially slidable control valve spool. A centering spring surrounds the support member, and it is mounted between a fixed collar and a slidable collar. When the valve spool is displaced for a "lower" mode of operation, the support member slidably moves through the slidable collar, and the centering spring is slightly compressed between the fixed and slidable collars.

Abstract: A differential fluid-pressure transducer having a housing with two spaced-apart fluid inlet openings and two fluid outlet openings. A spool is slidably disposed in the housing and has two oppositely-faced surfaces disposed intermediate the inlet openings, for receiving pressure from each respective inlet opening. The spool has a fluid passageway in flow communication from one of its two surfaces to a compartment at the end of the spool, whereby fluid pressure from one of the two inlet openings acts on both the one oppositely-faced surface and on the end of the spool which defines the compartment, and the fluid pressure at the other inlet opening influences the position of the spool, all for detecting the difference in pressure at the two inlet openings. Also, the spool can slide to a position which flow communicates the compartment to one of the housing outlet openings to thereby relieve pressure in the compartment.

Abstract: Apparatus for counting particle contamination in a liquid and including a hydraulic cylinder for receiving the liquid and having mechanism for forcing the cylinder piston to exhaust the liquid from the cylinder and into a sensor where the particles are counted. The apparatus includes electric switches connected to the sensor and responsive to the position of the cylinder rod for setting the sensor in various positions for counting. Also, liquid lines are connected with the sensor, and valves are used for directing the liquid to the cylinder and the sensor, and a line restrictor creates the desired pressure in the fluid. The apparatus may receive the liquid from several lines, through a dispensing valve, or it may receive the liquid from a special container.