Abstract: Fluid pressure changes are imposed on selected interior surfaces of a plug passageway of a plug valve to create torque. In one embodiment perturbations are provided in selected flow surfaces of the valve plug to create turbulent boundary layer flow along such surfaces which generates a beneficial stabilizing torque tending to reduce or eliminate holding forces conventionally provided by mechanical parts such as detent mechanisms. In another embodiment, pilot holds between interior and exterior plug surfaces are used to alter the fluid pressure at diagonally opposite locations relative to the plug rotation axis to produce the stabilizing torque.

Abstract: A three-way valve for high pressures and having a plug member rotatable within a valve housing. A seal arrangement is offset from the plug member to define a space in which system fluid pressure may be trapped for the purpose of acting on the plug member to offset system fluid pressure applied in an opposite direction to the plug member. Accordingly, frictional engagement of the plug member with the valve housing is reduced.

Abstract: A rotary valve assembly is disclosed in which a rotary valve member is located within a casing having one or more fluid inlets and a plurality of fluid outlets. The rotary valve member has a fluid conduit which extends in a generally radial direction and which communicates with the fluid inlet. Fluid orifices communicate with the fluid conduit and exit through opposite sides of the rotary valve member to thereby minimize, or eliminate altogether, axial forces acting on the rotary valve member. Fluid outlet passages communicate with the two fluid orifices during at least part of the rotation of the rotary valve member to direct the pressurized fluid to the valve outlets. The rotary valve may include a pair of rotary valve members drivingly connected to each other such that they rotate synchronously. The connection may include gear teeth formed on the adjacent peripheries of the rotary valve members such that rotation of one of the valve members causes rotation of the other.

Abstract: A marine outboard drive having an outboard drive unit that includes a bevel gear forward, reverse transmission having hydraulically operated clutches. A hydraulic pump for actuating the clutches and for lubricating the transmission is driven off the rear end of the input shaft and control valve means selectively communicates the fluid from the hydraulic pump with the hydraulic clutches. The valve means is a rotary plug type valve but is constructed so as to minimize axial and radial forces acting that would tend to bind its movement. The construction of the outboard drive unit is such that the bevel gear transmission and hydraulically operated clutches can conveniently be inserted through like diameter oppositely facing openings formed in the upper end of the housing assembly of the outboard drive unit.

Abstract: A liquid fuel shut-off valve for insertion through the feed pipe opening and mounting inside a fuel tank including, in combination, a valve body having an inlet and an outlet joined by a first bore aligned axially with the feed pipe through which the fuel is fed to fill the tank, a valve spool rotatably mounted in a cross-bore formed in the valve body between the inlet and the outlet and attached to a float extending outward from the valve body that is responsive to the level of liquid in the tank, and a valve shut-off formed in the spool including a second bore formed transverse thereto for passing fuel between the inlet and the outlet, and a relief opening formed in the trailing edge of the wall of the second bore allowing progressive rotation of the second bore from a first position in full hydraulic alignment with the first bore to a second position in full hydraulic closure with the first bore free of a countervailing hydraulic turning moment developed by the flow of fuel there through.

Abstract: A valve stem sealing means comprising first and second seal assemblies, the first seal assembly being proximate a valve plug and comprising an expandable ring adapted to be expanded by pressure within the valve to effect a first seal around the valve stem, and the second seal assembly being nearer a free end of the valve stem and comprising a second expandable ring adapted to be expanded by contact with a selectively movable member to effect a second seal around the stem.

Abstract: A valve stem sealing means comprising first and second seal assemblies, the first seal assembly being proximate a valve plug and comprising an expandable ring adapted to be expanded by pressure within the valve to effect a first seal around the valve stem, and the second seal assembly being nearer a free end of the valve stem and comprising a second expandable ring adapted to be expanded by contact with a selectively movable member to effect a second seal around the stem.

Abstract: A butterfly valve adapted for controlled variation in the area of the leading wing of the valve plate. The valve plate is comprised of two parallel plate-like members which are relatively translatable in mutually parallel directions. The relative translational movement further covers or uncovers an open area formed through one of the two members on the leading wing thereof. Movement of the valve plate occurs as either rotational movement of the entire valve plate or relative translational movement between the foresaid members. The type of movement depends on whether the force exerted on the members by a biasing mechanism is exceeded by the torque exerted on the valve plate by a conveyed fluid.

Abstract: A flow modulator (48) for a butterfly valve (40) incorporates a first protrusion (64) on the high-pressure side (52) of the modulator and a second protrusion (66) on the low-pressure side (54). The second protrusion (66) is spaced from the leading edge (60) to define a surface portion (88) of the low-pressure side (54). In operation, the second protrusion (66) functions as a flow restrictor that increases pressure in a region (86) of the flow path (44) bordered in part by the second protrusion and the surface portion (88). This increase in pressure serves to minimize the net aerodynamically-induced closing torque exerted on the modulator (46). The height of the second protrusion and its distance from the leading edge are shown to be important design parameters. In addition, the use of a third protrusion (114) for reducing torque drop-off at high rotational angles is disclosed.

Abstract: A method for facilitating control of a butterfly valve, butterfly valves (40, 180) adapted for use with the method, and a fluid system (242) incorporating such valves are disclosed. All three use or incorporate butterfly valve structure that provides for relative translational movement (246) between the valve plate (42, 182, 248) and a pivot axis (232) in order to alter fluid dynamic torque exerted on the valve plate.

Abstract: A kelly valve includes a ball valve structure (10) having a ball valve member (40) with a central bore (42) therethrough mounted within a valve chamber (38) for rotation between open and closed positions. A fluid pressure equalizing opening or port (60) is provided in the quadrant of the ball valve member (40) exposed to the upstream flow passage (20) in closed position (FIG. 2) and exposed to the valve chamber (38) in open position (FIG. 1) thereby making the ball valve member (40) easy to rotate manually even at high downstream fluid pressures.

Abstract: a balanced butterfly valve method and apparatus having a valve plate pivotally supported within a mounting body. The valve plate is capable of both rotational and translational movement in response to rotation of an input shaft. A spring is provided to resist translational movement of the valve plate. Differential gearing is used to convert rotational movement of the input shaft into rotational and translational movement of the valve plate depending on the relationship between the force exerted by the spring and the torque exerted on the valve plate by the fluid.

Abstract: A rotary valve has a valve body having at least one cylindrical hole, and casings provided with sleeves/plugs having an outer diameter substantially equal to an inner diameter of the cylindrical hole. The sleeves/plugs are provided in coaxial relation with the cylindrical hole. A flow of fluid is controlled by the relative motion between the valve body and the casings. The rotary valve may be provided with a high response time even by a small drive force.

Abstract: A balanced-torque butterfly valve (40) incorporates a pivot mechanism (52) designed to provide for bimodal movement of the valve plate (42). The valve plate (42) has a cavity (54) formed therein to receive the pivot mechanism (52) and to accommodate translational movement of the valve plate relative to the mechanism. This eliminates fluid dynamic effects that would be produced if the mechanism were positioned in the flow path (44) and external to the valve plate (42). The pivot mechanism (52) comprises a center shaft (70) rotatable relative to the valve plate (42), and a carrier shaft (72) which is in fixed rotational relation to the valve plate (42) and extends through the mounting body (46). This permits both translational movement of the valve plate (42), and detection of its rotational position from a vantage point outside of the flow path (44).

Abstract: A butterfly valve method and apparatus (10) employing a variably positionable pivot shaft (30). The apparatus (10) comprises a duct (16), a valve plate (12), and a pivot shaft (30). Near closed rotational positions of the valve plate (12), the plate is pivotally supported by a support shaft (18) which is movably secured to the duct (16). Over a substantial range of open rotational positions, the valve plate (12) is pivotally supported by the pivot shaft (30), which is translationally movable relative to the valve plate (12) so that fluid-dynamic torque exerted on the plate can be altered. The method comprises the steps of rotationally moving the valve plate (12) away from the closed position whereby fluid-dynamic torque is increased, and translationally moving the pivot shaft (30) relative to the valve plate whereby the torque is then decreased.

Abstract: A method for exploiting the net torque exerted by a conveyed fluid on the valve plate of a butterfly valve to facilitate control of the valve, and a butterfly valve (40) adapted for use with the method are disclosed. The method employs translational movement of the valve plate to facilitate rotational movement of the same and to effect dynamic torque balancing. The butterfly valve (40) employs a differential gear (50) as a mechanical resolver to produce either rotational or translational components of movement depending on whether the net torque exerted by the fluid is sufficiently high to overcome impedance to translational movement.

Abstract: A method for opening a sealingly closed, balanced-torque butterfly valve, and apparatus adapted for use with the method. The butterfly valve (40) comprises a valve plate (42) having a peripherally disposed seal (162) seated in an annular recess (160). A flow passage (164, 166) is formed in the valve plate (42) and fluidically connects the recess (160) to the downstream-facing surface of the valve plate. A check valve (168) is disposed in the flow passage (164, 166) to alternately block or permit flow therethrough. Outwardly directed pressure exerted by high-pressure fluid on the seal (162) is relieved by opening the check valve (168) in reponse to a slight translational movement of the valve plate (42) relative to a rotatable shaft (72) which pivotally connects the valve plate to the duct (146).

Abstract: A rotary fluid pressure device is provided of the type including a gerotor gear set (17) including an orbiting and rotating star (27) providing output torque by means of a main drive shaft (41). The device includes a valve housing section including a relatively thicker outer housing (61) and a relatively thinner inner housing (73) press-fit within the outer housing with an interference fit causing a preload force equal to the equivalent force of a predetermined fluid pressure, to avoid expansion of the spool bore (81). Disposed within the spool bore is a spool valve (55) which is relatively solid and able to withstand the predetermined fluid pressure without collapse of the spool valve. The spool valve defines axial slots (93) and (95) communicating by means of passages (97 and 99) with pressure-balancing recesses (101 and 103), whereby the valve spool is axially pressure balanced. The motor has improved volumetric efficiency, as well as improved mechanical efficiency.

Abstract: A butterfly valve includes a duct defining a fluid flow path and a plate-like valve member pivotal in the duct to in one position span and close the latter. The valve member is pivotal to a second position spanning the duct and extending parallel to the flow path to allow fluid flow therein. Means are provided for altering the effective area distribution of the valve member about its pivot axis to decrease the operating torque required by the inventive valve in comparison with conventional butterfly valves.

Abstract: A butterfly valve includes a duct defining a fluid flow path and a plate-like valve member pivotal in the duct to in one position span and close the latter. The valve member is pivotal to a second position spanning the duct and extending parallel to the flow path to allow fluid flow therein. Means are provided for altering the effective area distribution of the valve member about its pivot axis to decrease the operating torque required by the inventive valve in comparison with conventional butterfly valves.

Abstract: A butterfly valve includes a duct defining a fluid flow path and a plate-like valve member pivotal in the duct to in one position open and close the latter. The valve member is pivotal to a second position spanning the duct and extending parallel to the flow path to allow fluid flow therein. Means are provided for altering the effective area distribution of the valve member about its pivot axis in order to effect pivotal movement of the valve member in response to fluid dynamic flow forces. An actuator carried upon the valve member cooperates with the duct to forcefully effect initial opening and final closing movements of the valve member.

Abstract: A gasketless air damper includes a cylindrical sleeve having an inwardly protruding integral seal ridge. A circular blade damper disposed for rotation in the sleeve has integral oppositely oriented edge seals that aerodynamically interact with airflow through the damper and which, in a closed position, provide for a tight gasketless seal between the damper blade and the seal ridge integrally formed in the damper sleeve.

Abstract: An improved hydrostatic steering mechanism is disclosed having a rotary valve with a radially displaced resilient feedback mechanism.

Abstract: A fluid controller (15) is provided of the type for directing pressurized fluid from a source (13) to a steering cylinder (17). The controller includes a housing defining right and left turn ports (32 and 34) and corresponding annular grooves (32g and 34g). The controller valving includes a cylindrical sleeve (37) and a spool (35). Steering against the cylinder stops results in trapped pressurized fluid in one of the annular grooves (32g or 34g) after the valving returns to the neutral position. The sleeve (37) is provided with pressure balancing passages (93 and 97) which are positioned to communicate trapped pressurized fluid into pressure balancing areas (85 or 99, respectively). The pressurized fluid in the balancing areas is able to counteract the clamping force on the sleeve resulting from the trapped fluid in one of the annular grooves (32g or 34g), and thereby prevent a subsequent stiction condition when the vehicle operator attempts to begin the next steering maneuver.

Abstract: A profiled seal which is subjected to the influence of gas pressure forces in a pressure chamber associated with a rotary slide valve is provided with an enlargement, facing the slide valve, of its inner cross section in order to prevent an inadmissibly large increase of the contact pressure forces between the profiled seal and the slide valve, with an enlargement.

Abstract: A hydraulic valve has a tapered plug rotatable in a complementary tapered bore in a stationary housing so that the axial position of the plug controls the magnitude of a leakage path between the two parts. The magnitude of the leakage path is sensed and used to control the axial position of the plug in a negative feedback arrangement so that the valve plug floats on a film of escaping hydraulic fluid and can be readily rotated by a low power actuator. Ports in the stationary member and passages in the plug are arranged so that both static and preferably also dynamic and hydraulic forces acting on the plugs are balanced. The valve is contained in a closed housing, preferably together with the actuator.

Abstract: Valve which consists of a body (1) provided with a flow passage, of a closing member (2), such as, e.g., a flap, fitted in the flow passage (3) pivotably or turnably and having no passage opening, and, if necessary, of jointly operative sealing members (6) fitted between the closing member (2) and the valve body (1). In the flow passage (3) in the valve body (1), after the closing member (2), at the outlet side of the flow, one or several attenuation member or members (9) are fitted, which are placed one after the other at a distance from each other and from the closing member (2), which the closing member is in the closed position, and which reduce the cross-sectional area of the flow passage (3). The attenuation member or members (9) may be provided with holes or openings (12) passing through them.

Abstract: A four-way valve is provided, for selectively interconnecting pressure supply and return lines with control pressure lines of a hydraulic device, having means for independently balancing the valve against pressures exerted on the valve by any one or more of the pressure lines and at any operating position of the valve. These pressures exerted on the valve would otherwise restrict or prevent actuation of that valve. This balancing means exposes a minimum surface area of the valve to high pressure forces and isolates the fluid pressure in the pressure lines until interconnection is made by valve actuation.

Abstract: A non-locking tapered plug valve is provided which prevents taper locking of the plug member by ensuring against pressure responsive plug movement toward the small extremity thereof due to positive or negative hydraulic pressure transients. The chambers at each axial extremity of the plug member are of such volumetric relation during positive pressure transients that the chamber at the small extremity of the plug reaches equilibrium with flow passage pressure before the chamber at the large extremity of the plug member thus ensuring that any pressure responsive resultant force acting on the plug member is directed toward its large extremity. To avoid taper locking during a negative pressure transient, an equalization passage with a check valve is provided to permit unidirectional flow from the large extremity of the valve chamber to the main flow passage.

Abstract: A strainer for trapping solid particles entrained in a fluid flowing through the strainer includes a two-chambered housing, each chamber containing a removable strainer basket. The strainer also includes a plurality of valve mechanisms for routing fluid flow through the two chambers in a predetermined manner. A user actuated directional flow control valve includes a multi-ported ball member rotatably supported by and between a pair of opposed valve seat plates, each associated with a respective one of the chambers wherein rotation of the ball directs fluid flow through it into one or the other or both of the chambers. An optional seal member, engageable with the ball, acts at a predetermined position of the ball member to block inlet fluid flow through any of the ports in the ball member thereby providing a shut off condition. A pair of spring biased, normally closed, check valves are used to automatically control the flow of strained fluid out of the strainer chambers.

Abstract: A pressure balanced ball valve assembly includes a ball valve mounted within a unitary cage which has limited axial movement within a stationary tubular body. Annular pistons are slidably mounted within the cage for movement toward and away from the outer surface of the ball valve. Pressure transfer balance conduits extend from locations on one side of the ball valve to annular chambers at opposite ends of the cage. The effective area on the ball valve subjected to upstream pressure is balanced by the effective area of an annular chamber in which the same unit pressure acts on the downstream end of the cage. The balance conduits each lead from one side of the ball valve to a remote chamber at the other end of the cage.

Abstract: An automatic valve shut-off system useful for gas cylinders and the like employing a pneumatically actuated rotatable shaft to engage the valve handle on the cylinder. A control box is located remotely and conduits carry pressurized gas to energize the pneumatic activator. Solenoid or manual type operated switches select the delivery of pressurized gas to the cylinder and a pneumatic feed back device is provided to indicate the position of the valve handle.

Abstract: The invention is a novel hermetic tapered plug valve having a spring-like resilient mechanism for providing axial balance to the plug and thereby prevent valve lock up.

Abstract: The valve includes a tubular housing member that is connected in a string of a tubing that extends into an oil or gas well. The upper end of the tubular housing member is rotatable and is connected through actuators to a valve member that is pivotally supported in the tubular housing member. Rotation of the upper end of the tubular housing causes the actuators to move linearly and in opposite directions simultaneously pivot the valve member between open and closed positions. Pressure responsive means bias the seat toward the valve to maintain a fluid tight seal regardless of the direction of differential in pressure existing across the valve.

Abstract: A rotary valve having a hollow spool with a metering notch rotatable on a sleeve which is pressed into a valve body, the sleeve having an opening selectively and progressively alignable with said notch. A thrust needle bearing is trapped between a shoulder on the spool and a cap threaded into the valve body. A passage freely transmits pressure inside said hollow spool to the side of the bearing opposite said shoulders to reduce the thrust force imposed on said bearing.

Abstract: A ball valve is turned relative to its seat by means of three concentric sleeves mounted within a housing bore. Pins carried by the middle piston sleeve extend outward into slots in an outer carrier sleeve and inward into cam grooves in the outer wall of an inner drive sleeve. Axial movement of the middle sleeve under hydraulic pressure causes turning movement of the inner sleeve which then drives through bevel gears to turn the ball valve. The parts are constructed so that hydraulic forces within the housing acting to hold the ball valve in closed position against its seat are substantially balanced by forces in the opposite direction acting against the outer sleeve.

Abstract: A valve arrangement includes spherical core means rotatably mounted in a tubular member with operating means connected to the spherical core means and rotatably supported in a lateral opening in the tubular member to open and close the spherical core means for controlling flow through the tubular member. Seal means are provided between the spherical core means and tubular member and between the operating means and the tubular member with the operating means and the spherical core means having fluid passage means to conduct fluid from the tubular member fluid passage to act on the seal means between the operating means and the tubular member to substantially counterbalance the fluid pressure in the tubular member.

Abstract: The two supports for the plug in an eccentric rotary valve are joined and rotatively coupled by a wing member. As the plug is rotated from its closed position on the cooperating seat by the rotation of a shaft fixed to one of the plug supports, the wing member lies in the fluid flowing through the valve. This fluid flow causes the wing member to exert a rotative force on the shaft in the direction to move the plug in its valve-opening direction. This force shifts the inherently unstable control region of a rotative force, which the fluid flow causes the plug to exert on the shaft, and thereby extends and widens the range of the plug positions in which an external rotative force applied to the shaft, as by a valve actuator, can uniquely determine, and exert exclusive control over, the shaft and plug positions.

Abstract: The present invention encompasses a method and apparatus for assisting in the operation of air control dampers. An air deflector is positioned downstream from a rotatable damper in an air conduit. The deflector is positioned to direct air moving over one side of the damper against the damper during opening to assist in the opening movement and thereby reduce the amount of weight which would otherwise be required. The same deflector is positioned so that upon closing of the damper air will be deflected against the opposite side of the damper blade to augment the torque forces tending to close the damper while also reducing the pressure drop from one side of the damper to the other. In another embodiment of the invention a sail blade is provided upstream from the control damper to assist in closing the damper at low flow conditions.

Abstract: A rotary valve comprising a spherical segment supported on arms extending radially from aligned stub shafts. Carried by the arms is a vane which is circular in outline and of maximum thickness along the diameter parallel to the axis of the shaft, tapering to lesser thicknesses in both directions transverse of that diameter. In addition, the vane is tilted about the maximum thickness diameter in the rotary direction opposite to valve opening movement, so that it remains exposed to the flow stream through full movement of the plug. The flow stream acting against the vane biases the plug toward closed position, cancelling the effects of the flow stream acting against the plug itself.

Abstract: A control valve for fluids has two relatively rotatable plates, each having ports which cooperate to control fluid flow. The plates are biased towards one another, and one of the plates is provided with lands round its ports, these lands creating a space between the plates, to which space the fluid pressure at the valve inlet is admitted. The pressure between the plates opposes the inlet pressure acting on one of the plates, and the areas of the aforesaid one plate subjected to the inlet pressure are selected so as to produced a desired force between the plates.

Abstract: A rotary four way tandem center valve including a spool member provided with a central spool projection with four axially extending grooves in its outer peripheral surface and two intersecting channels defined therein, a first and second operation port, an inlet and outlet port, and means for directing pressure passing from the inlet port to the outlet port to a selected one of said operation ports while at the same time relieving pressure in the other operation port.

Abstract: A valve comprises a casing having a passageway therethrough for the flow of fluid with a bore intersecting the passageway. A flow regulating member is rotatably mounted in the bore for blocking the passageway in a valve closed position of the flow regulating member. The flow regulating member has a port therethrough for connecting and being in communication with the passageway in a valve open position. The flow regulating member and the casing define a first chamber at one end of the flow regulating member. A stem is rotatably mounted within the casing and is mechanically coupled to the flow regulating member to rotatably drive the flow regulating member within the casing. The stem has an annular rim formed toward and positioned within the first chamber. At least one annular seal surrounds the stem to effect the seal between the stem and the casing.

Abstract: An improved plug valve is of the type that includes a valve body having a bore extending therethrough and a pair of passages intersecting the bore and being substantially normal to the axis of the bore. A valve plug is disposed within the bore for selective rotation between an opened and a closed position to respectively align and misalign a port through the plug with the passages. A first circumferential sealing member between the plug and the bore above the port and the passages and a second circumferential sealing member between the plug and the bore below the port prevents fluid from escaping from an interior of the plug valve and balances fluid pressure acting on the plug. The improvements include providing opposed circumferential semi-circular grooves respectively on the bore and the plug to define a circumferential channel therebetween. The body includes a circular hole extending therethrough which is tangentially aligned with the channel.

Abstract: A tapered plug valve comprises a casing having a passageway therethrough for the flow of fluid and a tapered bore intersecting the passageway. A tapered plug is rotatably mounted in the tapered bore and is adapted to block the passageway when the valve is in a closed position. The plug has a bore which is adapted to connect and be in communication with the passageway when the valve is in an open position. The plug and the casing define an apex chamber at the small end of the tapered plug and a base chamber at the large end of the plug. A seal is provided at the large end of the tapered plug to sealingly divide the base chamber into a first and second cavity. A pressurized medium is ported into the apex chamber and the second cavity and the first cavity is vented to atmosphere.

Abstract: A rotary plug valve comprised of a valve body having a replaceable liner and valve plug disposed therein. The liner is formed of a pair of axially split complementary liner members, including an upstream liner member and a downstream liner member, having at least one radially elastically deformable retaining member disposed around the periphery thereof.

Abstract: A valve is provided adapted to multiple modes of use including filter, backwash, rinse, recirculate, and direct to waste, on a swimming pool filter of the type normally filtering water under pressure through a backwash-regenerable filtering medium disposed in a filter tank. The valve comprises closely interfitting, relatively rotatable inner and outer sections having coaxially tapered annular walls defining interiorly open spaces respectively within the sections; the outer section wall has formed therein circularly spaced outer ports including an inlet port, a first outlet port, and a second outlet port. The inner section is normally seated against the outer section wall, its interior space being adapted to define a continuation of the filter tank in continuously hydraulically filled relation against unseating pressure imbalances across the inner section.

Abstract: A ball valve to accommodate liquid flow having a rotatable ball element formed with a plurality of reaction faces which when contacted by liquid flow through the valve serve to generally counterbalance the normal self-closing forces exerted upon the ball element by the liquid flow.

Abstract: The valve body is in the form of a segmented ball section and is integrally formed on a rotatable spindle as a cantilevered extension of the spindle. The segmented ball section includes an annular seating surface on one side for seating and sealing engagement with a valve seat in one of the openings of the valve. The opposite surface of the extension is substantially flat to present a limited profile to flow when the valve body is moved out of sealing engagement with the valve seat into an open position. The configuration of the valve body places 20% less ball structure in the flowing stream compared to existing partial ball constructions. The one-sided mounting of the valve body permits complete removal of trim for maintenance or replacement without removal of the valve body from a pipeline. Thus, "out of line" trim changes can be made without having to pull the valve from the pipe.

Abstract: A valve comprising a casing having a passageway therethrough for flow of fluid and a tapered bore intersecting the passageway, a tapered plug rotatably mounted in the tapered bore adapted to block the passageway in valve closed position of the plug and the plug having a port adapted to connect and be in communication with the passageway in valve open position, the plug and casing providing chambers at opposite ends of the tapered plug, means for connecting the chambers to the port to dynamically balance the plug within the casing when the plug is partially or fully open, a biasing means is provided in the casing to axially bias the tapered plug in the direction of the larger end of the plug.