A solenoid valve of the hung diaphragm type includes a diaphragm assembly having a pilot valve seat mounted for movement toward and away from a main valve seat in a valve body, Hydraulic control valves a plunger assembly consisting of a valve disc holder reciprocably mounted in the pole piece of the electromagnetic valve resiliently supports a valve disc for cooperation with the pilot valve seat, being actuated by a plunger slideably mounted in an enclosure tube. Balance Valves The valve holder is biased to an upper position and a pickup extension spring is coupled between the valve holder and diaphragm valve assembly to lift the latter from the main valve seat. API CAST STEEL VALVESA necked down end of the valve holder prevents abrasion at the edge of the pole piece while a groove in the actuating face of the plunger prevents excessive distortion of the end of the pole piece due to repetitive impacts.  A solenoid valve, comprising a valve body having a main valve seat, a diaphragm valve assembly supported in said body for movement toward and away from said main valve seat, said diaphragm valve assembly comprising a diaphragm valve, means for limiting valve movement and a pilot valve seat, a plunger assembly supported for movement toward and away from said pilot valve seat, said plunger assembly comprising a valve disc engageable with said pilot valve seat for controlling fluid flow therethrough, main spring means for biasing said plunger assembly and a plunger for moving said plunger assembly, an electromagnet mounted on said body for actuating said plunger in response to electrical current, and a pickup spring joining said plunger assembly and said diaphragm valve assembly for providing bias force upon said diaphragm valve assembly, said plunger assembly further comprising a disc holder having a stem vertically slideable in a pole piece and a disc spring resiliently supporting said valve disc therein, and said disc holder being engaged by said pickup spring. In known forms of solenoid valves of this type a diaphragm is disposed relative to a main valve seat for controlling the flow of fluid through the valve, being aided in its closing and opening actions by the fluid under pressure being controlled by the valve. In such an arrangement a pilot valve is often typically used to open or close an orifice through the diaphragm itself to achieve the necessary differential fluid pressures for control of the position of the diaphragm and which pilot valve opening is selectively opened and closed by the moving plunger of the electromagnetic coil assembly. In arrangements of this type the pilot valve is controlled by an elastomeric valve disc supported in a disc holder which receives its actuation from the moveable plunger. Spring means are provided for return movement of the disc holder and its assembly to a normally inactivated position while a second spring acting between the valve body and the diaphragm assembly serves to urge the latter also to a normally open position. The springs are selected in order to obtain a proper operating characteristic for the valve assembly and it is apparent with a great number of components involved that assembly procedures for the valve structure are difficult and complicated and subject to misassembly at high production levels.

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