Abstract: A servo valve body is made by first boring a central cylindrical passageway, for receiving a valve spool, through an elongated, substantially rectangular valve block of tool steel. A plurality of cross slots are cut through the valve block, from one side through to the opposite side, at intervals along the length of the block, orthogonally to the axis of the passageway. The cross slots are cut by use of electronic discharge machining technology. The cross slots serve as fluid flow chambers when the cross slots are terminated by transition plates secured to the opposite sides of the valve block. The transition plates provide fluid inlet, outlet and drain ports. The valve block in combination with the transition plates comprises the servo valve body.

Abstract: A double-containment thermoplastic pipe assembly provides for transfer of differential thermal expansion forces to rigid external supports. The assembly includes a flanged restraint coupling having an inner carrier pipe portion, an outer containment pipe portion, a wall connecting the inner and outer pipe portions, and a radially extending flange around the outside of the containment pipe portion. The flange is secured to an external support such as a manhole for underground system by being cast into the wall of a cast-in-place manhole or by being engaged by rings on each side of the flange for precast manhole systems. The outer pipe terminates at the manhole wall so that the containment function within the manhole is performed by the manhole inself. For above-ground applications, the coupling is secured by engagement of the flange with a cast concrete wall or metal saddle connected to an underground footing.

Abstract: The disclosed valve may be configured for use as a pressure relief valve, pressure regulator valve or pressure reducing valve. A pair of opposed valve members defines a radial flow path therebetween which extends from the outer radial peripheries of each valve member to an axial bore formed in one of the valve members. The other valve member comprises a substantially pressure balanced piston, the axial movements of which control flow through the valve. A pilot valve for relieving pressure above the piston has its inlet positioned within a cavity formed on the upper surface of the piston.In a second disclosed valve, a pair of opposed valve members defines a radial flow path therebetween which extends from the outer radial peripheries of each valve member to an axial bore formed in one of the valve members. The other valve member is mounted on a stem having an upper end which is urged upwardly by a spring disposed around the stem.

Abstract: The disclosed valve may be configured for use as a pressure relief valve, pressure regulator valve or pressure reducing valve. A pair of opposed valve members defines a radial flow path therebetween which extends from the outer radial peripheries of each valve member to an axial bore formed in one of the valve members. The other valve member comprises a substantially pressure balanced piston, the axial movements of which control flow through the valve. A pilot valve for relieving pressure above the piston has its inlet positioned within a cavity formed on the upper surface of the piston.

Abstract: A cartridge valve is received in a housing for restricting fluid flow to the top of a piston in the housing. The cartridge valve includes a pair of opposed substantially parallel working faces, one of which is movable toward the other. The fixed face includes a central bore into which fluid flows radially from the outer peripheries of the working faces.

Abstract: A valve body includes a cylindrical seat having a substantially flat working face. A cylindrical valve member having a working surface thereon is slidable toward and away from the seat face to vary flow from the outer peripheries of the seat and valve member into an orifice extending into the seat and in communication with the seat face. The valve member is mounted on a stem which is in threaded engagement with the radially inner surface of an annular member. The outer surface of the annular member is in threaded engagement with the valve body. The inner threads have 12 threads per inch and the outer threads have 11 threads per inch thereby moving the valve stem 0.0075 inches per 360.degree. revolution of the annular member.

Abstract: A pair of opposed valve members defines a radial flow path therebetween which extends from the outer radial peripheries of each valve member to an axial bore formed in one of the valve members. The other valve member is mounted on a stem having an upper end which is urged upwardly by a spring disposed around the stem. A substantially cylindrical element is threadably engaged in the upper end of a valve body in which the valve members are received and the stem is urged thereagainst. In another embodiment, the stem is fixedly connected to the cylindrical element. Rotational movement of the cylindrical element axially moves the stem thereby controlling flow through the valve.

Abstract: The disclosed valve may be configured for use as a pressure relief valve, pressure regulator valve or pressure reducing valve. A pair of opposed valve members defines a radial flow path therebetween which extends from the outer radial peripheries of each valve member to an axial bore formed in one of the valve members. The other valve member comprises a substantially pressure balanced piston, the axial movements of which control flow through the valve. A pilot valve for relieving pressure above the piston has its inlet positioned within a cavity formed on the upper surface of the piston. In a second disclosed valve, a pair of opposed valve members defines a radial flow path therebetween which extends from the outer radial peripheries of each valve member to an axial bore formed in one of the valve members. The other valve member is mounted on a stem having an upper end which is urged upwardly by a spring disposed around the stem.

Abstract: The disclosed valve may be configured for use as a pressure relief valve, pressure regulator valve or pressure reducing valve. A pair of opposed valve members defines a radial flow path therebetween which extends from the outer radial peripheries of each valve member to an axial bore formed in one of the valve members. The other valve member comprises a substantially pressure balanced piston, the axial movements of which control flow through the valve. A pilot valve for relieving pressure above the piston has its inlet positioned within a cavity formed on the upper surface of the piston.

Abstract: A flow regulating cartridge assembly that can be adjusted from substantially zero flow to a predetermined maximum flow determined by the maximum size of a flow controlling orifice located within the valve assembly. The valve includes a spool slidably mounted within a step bore located in the valve body which is operative to control the fluid communication between an inlet port and a bypass port. The spool includes an adjustable orifice for adjusting a regulated fluid flow through a regulated port. The spool member threadedly carries an adjustment stem which includes a tapered end that is adapted to move into and out of the orifice to adjust its effective orifice size. A coupling member including an adjustment segment extending externally of the valve body includes a coupling arrangement which allows relative axial movement between the adjustment stem and the coupling member but prevents relative rotation.

Abstract: A control valve that can be used as a pilot-assisted pressure relief valve or as a sequence valve, which is substantially insensitive to system back pressure. The valve comprises a valve body 10 defining a multistep bore 36, and a valve member 44 engageable with a coaxial valve seat 46, both supported for reciprocating motion within the bore 36 and cooperating to control the fluid communication between first and second ports 30, 32 defined in the valve body 10. A primary biasing spring 48 enclosed within a vented spring chamber 52 urges the valve member 44 into engagement with the valve seat 46. Fluid pressure at the first port 30 exerts fluid forces on the valve member 44 that opposes the primary spring force. The valve member 44 is a unitary element including first and second annuli 44a, 44b joined by a reduced diameter shank portion 44c. A radial surface on the first annuli 44a defines a net effective pressure area against which fluid pressure at the port 30 is applied.

Abstract: A pilot-assisted pressure relief valve including a valve body 10 defining a first and second plurality of ports 30, 32 and an internal stepped bore 40 that slidably supports an elongate, tubular primary piston 34 engageable with a valve seat 36 mounted at one end of the valve body bore, which cooperate to control fluid communication between the first and second plurality of ports. The piston 34 is biased towards a flow interrupting position by a spring and is biased towards an open position by fluid pressure at the first plurality of ports. A pilot-operated piston 70 is mounted coaxially with the primary piston and is operative to engage the primary piston 34 and oppose the spring force thereby reducing the effective relief setting of the valve.

Abstract: A normally open, two stage solenoid actuated flow control valve having a pressure relief function, in which a poppet assembly comprising a spring biased poppet, a range spring and a spring adjusting screw, controls the communication of balancing fluid pressure to a primary valve member. The adjustment screw includes an axial extending shaft engageable with an externally extending adjustment stem; rotation of the stem effects concurrent rotation and axial displacement of the adjusting screw within the poppet sleeve. An armature is disposed in axial alignment with and intermediate the stem and the poppet assemby so that the poppet assembly can be driven to engagement with its associated seat by the actuation of the solenoid or by the direct axial displacement of the adjustment stem.

Abstract: A vehicle power steering system which effects steering with a pair of fluid actuated cylinders, one cylinder being operatively connected to each steerable wheel. Each cylinder is normally powered independently of the other cylinder so that both cylinders steer the vehicle. A pressurized fluid flow from a single source is divided for parallel flow along companion fluid flow paths to the individual cylinders. In response to a pre-determined pressure decrease sensed in one of those fluid flow paths a pressure responsive fluid diverter automatically diverts fluid flow from the reduced pressure flow path to the companion path so that all pressurized fluid in the system is then utilized to power one of the cylinders.

Abstract: A free delivery controlled return valve, of the type employed in fluid power hoisting apparatus, which controls the speed at which a load is lowered as a function of load magnitude. An improved valve structure is disclosed which overcomes false load signals, such as those generated when the hoisting apparatus' lift cylinders are fully extended against a stop, and which thus permits the load platform to descend at an appropriate speed. An improved fluid sonic muffler is also disclosed.

Abstract: A vehicle power steering system which effects steering with a pair of fluid actuated cylinders, one cylinder being operatively connected to each steerable wheel. Each cylinder is normally powered independently of the other cylinder so that both cylinders steer the vehicle. A pressurized fluid flow from a single source is divided for parallel flow along companion fluid flow paths to the indivdual cylinders. In response to a pre-determined pressure decrease sensed in one of those fluid flow paths a pressure responsive fluid diverter automatically diverts fluid flow from the reduced pressure flow path to the companion path so that all pressurized fluid in the system is then utilized to power one of the cylinders.

Abstract: The combined sensor and control comprises a flow sensor through which passes working hydraulic fluid delivered by a pump through a hydraulic power circuit to a hydraulically operated power mechanism which is subjected to variations in load. The sensor senses incipient changes in a preselected rate of flow of the working hydraulic fluid by detection of very slight changes in the differentials in the pressure of the working fluid at opposite sides of a restricting orifice through which the working fluid is constrained to pass. These differentials in pressure, or pressure drops, operate a pneumatic pressure control device by which pneumatic pressure supplied to an actuator through a circuit, isolated from the working hydraulic circuit, is controlled. The pressure control device causes the applied pneumatic pressure to be varied almost instantly in a manner analogous to the slight variations in the normal preselected differential in pressure across the orifice.