A servo valve for an actuator is described. The servo valve comprises a housing having a plurality of ports, a sleeve disposed within the housing, the sleeve comprising an axis (A), an inner surface defining a cavity for the servo valve and a plurality of metering holes, each in communication with one of the ports, and a metering rod extending axially in the cavity for reciprocation along the axis to meter flow through the metering holes. The servo valve additionally comprises a first spring seal extending between the metering rod and the sleeve to close off a first end of the cavity and a second spring seal extending between the metering rod and the sleeve to close off a second, opposite end of the cavity.

Anti-rotation assemblies for use with fluid valves are disclosed. An example apparatus includes a retainer collar coupled at an end of a plug, the plug including a plug collar around which the retainer collar is disposed, the plug and the retainer collar being substantially flush at an interface between the plug and the retainer collar, a fastener extending transversely through the retainer collar and the plug collar to couple the retainer collar at the end of the plug, when the retainer collar and the plug are disposed within a valve body, a stem extends through the retainer collar and the plug to enable the plug to be moved within the valve body; and an anti-rotation collar to receive the retainer collar, the anti-rotation collar coupled at an end of a cage, the anti-rotation collar and the retainer collar having corresponding non-circular cross-sections to inhibit rotation of the retainer collar and the plug when the plug is moved within the valve body.

An example apparatus includes a valve body defining a fluid flow passageway between an inlet and an outlet, a cage disposed in the fluid flow passageway, a plug disposed in the cage, a retainer collar coupled at an end of the plug, where an exterior surface of the retainer collar includes a first engagement surface having a first non-circular cross-section, and an anti-rotation collar coupled at an end of the cage, where the anti-rotation collar has a second engagement surface defining an aperture to receive the retainer collar, where the aperture has a second non-circular cross-section, where the engagement surfaces interact to inhibit rotation of the retainer collar and the plug.

A pressure regulating valve assembly includes a housing. Also included is a valve sleeve mounted within a bore of the housing, the valve sleeve having a first portion and a second portion, the second portion having a diameter less than the first portion and received in a sense piston bore of the housing. Further included is a valve spool mounted within the valve sleeve. Yet further included is a sense piston disposed within the second portion of the valve sleeve. Also included is a damping orifice extending through an end portion of the second portion of the valve sleeve.