Abstract: A universal housing body for a refrigeration expansion device including a movable orifice piston. The body is adapted for interchangeable use with a piston of a first variety having a radial boss portion extending along a first axial distance, L.sub.1, from a forward boss end having an annular sealing surface of a first maximum sealing diameter, d.sub.max1, to a rearward boss end, and a piston of a second variety having a radial boss portion and an annular seal member having a forward surface defining with a rearward end of the boss portion a second axial distance, L.sub.2, therebetween greater than the first axial distance L.sub.1, and having a second minimum sealing diameter, d.sub.min2, greater than d.sub.min1 and less than d.sub.max1. The housing body has an internal fluid passageway extending from a forward end to a rearward end which couplable with a flange end of an associated adapter. An annular valve seat, having an inner diametric extent, d.sub.i, intermediate d.sub.min2 and d.sub.

Abstract: An actuator (24) for a valve (10) includes a housing tube (26) enclosing an internal cavity (48). A plunger (42) is mounted for movement in the internal cavity. The plunger includes four slots (50). Rollable spheres (58) are positioned in the slots between staked areas (62). A magnetic field created by electrical current passing through a coil (34) moves the plunger downward to open fluid flow through a control element (20). Flow through the control element enables controlled flow from an inlet (14) to an outlet (16) of the valve. The actuator construction provides for substantial elimination of sliding friction acting on the plunger, reduces hysteresis and the amount of power required to move the plunger, and facilitates accurate control of fluid flow rate through the control element.