Abstract: A poppet-type valve unit having annular elastomeric poppet which cooperates with an annular valve seat. The exterior profile defined by a pair of generally frusto-conical surfaces which are disposed radially inwardly and outwardly with respect to one another. The inner frusto-conical surface extends at a steeper angle or slope relative to valve movement direction than does the outer frusto-conical surface, thereby defining a peak where the two frusto-conical surfaces meet. This peak substantially corresponds in diameter to the diameter of the valve seat. This increases the flow area between the poppet and valve seat when the poppet is opened.

Abstract: A valve assembly having a single stem slidably supported within a bore formed in a one-piece valve body provided solely with four ports. The stem is hollow to permit the exhaust from two load ports to be directed into a single exhaust port. This single exhaust port can desirably be provided with a pair of flow controls to permit individualized control of the exhaust from each load port. The valve poppets are preferably axially press fit unto the valve stem, particularly on portions of the valve stem which are of slightly different diameters, to permit the individual poppets to be precisely axially positioned relative to one another and relative to the valve seats to achieve high tolerance and precision of operation.

Abstract: A valve assembly having a single stem slidably supported within a bore formed in a one-piece valve body provided with three ports which communicate with the bore at axially spaced locations therealong. The axially centermost port functions as a load port. The valve stem has a single valve poppet mounted thereon in encircling relationship thereto, which valve poppet is axially movable between a pair of opposed valve seats formed on the valve body for controlling communication between the load port and the bore. The stem has a passageway extending axially therethrough to maintain a balanced pressure axially of the valve stem.

Abstract: A four-way valve assembly provided with a housing having an elongate bore in which a single shiftable valve is slidably disposed. Electric solenoids are connected to opposite ends of the housing for effecting shifting of the valve between opposite ends positions. A pair of sleevelike liners are disposed in the bore, and an inlet port communicates with the bore between adjacent inner ends of the liners. A pair of load ports communicate with the bore through the individual liners and are spaced axially on opposite sides of the inlet port. A pair of exhaust ports communicate with the bore adjacent opposite ends thereof in axially outwardly spaced relationship relative to the load ports. The valve has an elastic valve ring mounted centrally of the rodlike stem and disposed to axially shift between and sealingly coact with valve seats formed on opposed inner ends of the liners.