Abstract: A multiple-bore throttle valve wherein the valve shaft is restrained from end play at a point between two of the flow bores. A passageway in the valve body between the flow bores intersects the valve shaft bore non-diametrically. The valve shaft has a circumferential groove at the point of intersection. A pin pressed into both the passageway and the groove axially restrains the shaft at that location. Since thermal expansion or contraction of the shaft in its axial direction can proceed only from the point of restraint, a dual-bore valve in accordance with the invention exhibits length changes in each bore equivalent to that of a single bore valve, which is less than half the shaft length change exhibited in at least one bore of a prior art dual-bore throttle valve. Similarly, a triple-bore valve exhibits expansion comparable to individual prior art single-bore and dual-bore valves, and a quadruple-bore valve exhibits expansion comparable to a prior art dual-bore valve.

Abstract: A damper mounting assembly for mounting a damper within an HVAC duct is provided. A damper mounting assembly has attachment clips secured to the damper blade before the damper blade is positioned within the duct. Shaft segments are inserted from outside the duct through axially aligned holes in the duct and are permanently received within the attachment clips affixed to the damper blade to provide support and control for the damper blade within the duct. A damper control handle is affixed to one of the shaft segments so that the position of the damper blade within the duct may be adjusted and thereafter locked in place.

Abstract: An improved valve disc assembly that can be easily and conveniently disassembled and reassembled with accurate positioning of the valve disc within the through bore of the valve body. A split clamp ring is provided for securing the seat retaining ring and valve seat onto the valve body for sealing engagement with the valve disc. The shaft through which movement of the valve disc to and between open and closed positions is accomplished, also includes a detent that automatically positions the valve disc within the bore upon reassembly of the valve.

Abstract: A throttle lever assembly for controlling the actuation of a throttle valve in an internal combustion engine has a throttle shaft pivotally secured to a housing. An idle stop lever is mounted to and radially extends from an end portion of the shaft for engaging a depending member of the housing to stop the rotation of the throttle lever assembly at an idle position. A return cam formed of thermoplastic/thermoset material is overmolded the end portion of the shaft and a portion of the idle stop lever. The molded return cam has a channel disposed about its cam surface for receiving an accelerator cable, a stud extending axially from the outer surface of the cam return, and a spring retainer extending axially from the inner surface of the return cam for maintaining a return spring in coaxial relationship with the shaft. The return cam may also include an idle stop member to replace the discrete idle stop lever.

Abstract: The object of the present invention is to provide an actuator possible to transmit an output from a power rod of the actuator as rotary motion, and to provide an exhaust brake unit using the actuator, easy to assemble, a small space necessary for installation, able to place the actuator in such a manner that an axis of a power rod of the actuator and an axis of a valve shaft are aligned in a line, and heat transfer from an exhaust channel to the actuator is minimized.

Abstract: A low friction fluid motor has a diaphragm mounted in a shell to divide the shell into first and second chambers, a port means for connecting the second chamber to a pressure or vacuum source, and an actuator assembly. The actuator assembly is connected to the diaphragm and includes an actuator member extending out of the shell through an aperture. The actuator is free of any seal member which is interposed between the actuator member and the shell and which functions to form a seal between the actuator member and the aperture in the shell. The aperture is oversized relative to the actuator member to allow free passage of the actuator member from the actuator assembly through the first chamber and out of the fluid motor.

Abstract: A valve gear comprises a valve 1 having a valve element and a valve stem, and an actuator having a driving shaft for operating the valve element of the valve. A connecting portion 7 is provided on either the valve or the actuator. A sleeve having a smooth inner surface is fixedly or rotatably fitted in a bore formed in the connecting portion 7 so as to slidably receive the valve stem and the driving shaft and slidably contact the inner smooth surface of the sleeve with outer surfaces of the valve stem and the driving shaft. The valve stem and the driving shaft inserted into the sleeve through the opposite ends, of the sleeve are provided at their end portions with respective coupling portions, so that the stem and the shaft are able to engage with each other only at the particular one point of relative rotation of the stem and the shaft.

Abstract: An air passage switching system includes a case forming an air passage, and a butterfly door for opening and closing the air passage. The door includes a door body, a rotation shaft for rotating the door body, and a seal member attached to the door body. A link member is connected to a first end of the rotation shaft, and the first end of the rotation shaft is rotatably held in a shaft receiving portion of the case through the link member. A first cylindrical portion is formed in the door body concentrically with the rotation shaft at an outer peripheral side of the first end, and a second cylindrical portion protruding to a side of the door body is formed in the case. The first cylindrical portion and the second cylindrical portion are engaged so that a small gap is formed between an outer peripheral surface of the second cylindrical portion, and an inner peripheral surface of the first cylindrical portion and an end of the seal member.

Abstract: An extension assembly for use with a damper assembly and for extending the damper assembly control shaft. The extension assembly is provided for coupling of a handle to the control shaft and includes an extension member, a locking member and a securing member. The extension member includes a connecting portion having a closed end and an open end. The open end includes a bore dimensioned to operatively receive the control shaft. The extension member further includes a shaft portion extending longitudinally from the closed end of the connecting portion. The shaft portion includes two parallel flat sides merging transversely with two opposite arcuate sides and dimensioned to be received by an aperture in the handle. The locking member provides the function of locking the control shaft within bore. The securing member ensures that the handle will remain a fixed distance from duct and provides a lock tight surface for a nut to engage and hold the handle.

Abstract: The objection of the present invention is to provide an actuator possible to transmit an output from a power rod of the actuator as rotary motion, and to provide an exhaust brake unit using the actuator, easy to assemble, a small space necessary for installation, able to place the actuator in such a manner that an axis of a power rod of the actuator and an axis of a valve shaft are aligned in a line, and heat transfer from an exhaust channel to the actuator is minimized.

Abstract: An alternate valve assembly for a smoke re-combustion device of a engine includes a pair of alternate valves which are symmetrically installed at each inlet of filters connected with branches of an exhaust manifold.

Abstract: A valve system for use in batch processing, particularly for preventing exposure of material to the environment during transfer from one container to another. The system in effect comprises two butterfly valve discs (5, 6; 105, 106), one (5; 105) on a container (12; 107) for transporting material to or from a reaction vessel (3; 103) and the other on the reaction vessel (3; 103) itself. Each valve disc (5, 6; 105, 106), when closed, shuts off the container (12; 107) or vessel (3; 103) respectively from the environment. When the container (12; 107) is connected to the vessel (3; 103) a shaft (9; 109) connected to one valve disc (5; 105) interengages with a shaft (10) connected to the other valve disc (6; 1006) to enable the discs (5, 6; 105, 106) to move simultaneously, and material may be transferred from the container (12; 107) to the vessel (3; 103) or vice versa.

Abstract: A gas turbine system has a shaft assembly for controlling a flap for the hot gases in the form of a solid stub shaft connected to a tubular shaft via a mechanical entrainer system either in the form of a set of links articulated to the stub shaft and the tubular shaft or in a radial claw arrangement in which between radial claws on the stub shaft, axial entrainers of the hollow shaft engage.

Abstract: A throttle body (10) for use with an air intake system of an internal combustion engine. The throttle body (10) includes a throttle valve (18), which includes a throttle plate (20) mounted to a throttle shaft (22) within a slot (26). The throttle shaft also includes a notch (32) extending between the slot (26) and the surface of the throttle shaft (22). The notch (32) allows for ease of manufacturing and assembly and also allows for a slight increase in air flow past the throttle valve with minimal reduction in bending strength of the shaft.

Abstract: A butterfly valve assembly is disclosed wherein a wedged shaped pin is used to position and fasten the butterfly disc to the valve shaft. The valve shaft, butterfly disc and wedged shaped pin are designed to cooperate in a manner that prevents relative movement between the valve shaft and butterfly disc without the necessity of pre-assembling and drilling the valve shaft and butterfly disc. This allows manufacture and repair without having to maintain the valve shaft and butterfly disc as a matched set. In the preferred embodiment, the butterfly disc has two intersecting apertures, one for insertion of the valve shaft, the other for insertion of a wedged shaped locking pin. The valve shaft is notched such that when it is inserted in the corresponding disc a locking pin with a wedged shaped flat may be inserted through a corresponding disc aperture causing an interference fit between the shaft pin and disc thus locking the disc in position relative to the shaft.

Abstract: A throttle plate-throttle shaft construction is formed by molding both components from composite plastic, the shaft having integral bosses which are received in holes formed in the throttle plate. The bosses are ultrasonically staked to lock the throttle plate onto the throttle shaft.

Abstract: An exhaust butterfly in an exhaust conduit of an internal combustion engine is supported by way of bearing journals by positive plug-in connections. To simplify installation, the bearing journals and the bearing sleeves are designed in such a way that, to install the exhaust butterfly, the bearing journals are each pressed completely into the respective bearing sleeves counter to the force of a spring. In the case of a multiflow exhaust line, between adjacent exhaust lines cylindrical transverse passages are provided in each of which a driver is rotatably mounted. At one end, the driver has a recess which is designed as a bearing sleeve and into which the bearing journal of the first exhaust butterfly is inserted to produce a driving connection. The other end of the driver is designed as a bearing journal which is likewise inserted into a recess in the second exhaust butterfly to produce a driving connection.

Abstract: An exhaust flow control valve operable over high temperature ranges, comprising: a cylindrical flow housing having a cylinder axis and defining a flow passage; a valve plate pivotably mounted within the cylindrical flow housing, wherein the valve plate has a first facing surface, a second facing surface and a perimeter surface and wherein the valve plate has a pivot axis perpendicular to cylinder axis; a first seat extending radially inward from a first approximate 180 degree portion of an inner perimeter of the cylindrical flow housing, wherein the first seat forms a first partial annular surface having a substantially constant width in a radial direction over an entire arcuate length of the first seat and wherein the first seat faces a first direction parallel to the cylinder axis; a second seat extending radially inward from a second approximate 180 degree portion of the inner perimeter of the cylindrical flow housing, wherein the second seat forms a second partial annular surface having a substantially co

Abstract: A drop tube for underground fuel storage tanks and the like has a flow restriction section that includes a plate or disc mounted for rotation and controlled by a float located outside the section. Unlike overfill shut-off valves that slam against a sealing valve seat and require springs and cams for their operation, the subject restrictor simply and slowly rotates the plate between a non-restricting position and one in which the plate closes off the delivery liquid flow. Since the plate and interior wall of the tube are not sealed, liquid above the restrictor can bleed past the plate into the storage tank after the delivery valve on the truck is closed. Overfill is unlikely because it would take several hours to overfill with the plate in the restricting position.

Abstract: A chemically-resistant fluid control valve is disclosed generally comprising fluid inlet and outlet passages separated by fluid control means, which control means comprise a flapper plate disposed in the fluid passageway and mounted on a rotatable shaft that passes laterally through the fluid passageway by means of releasable fasteners adapted to engage correspondingly-shaped fastener elements of the flapper plate, which elements are also adapted to receive the shaft in a channel between the fastener elements, wherein at least all wetted surfaces of each of the several components consist essentially of a chemically-resistant material.

Abstract: A fluid flow control damper assembly and associated method are characterized by a self-contained unit comprising a support base for external mounting to a side of a duct, a damper vane mounted to the support base for movement between open and closed positions, the damper vane being located inwardly of the inner side of the support base for positioning interiorly of the duct when the support base is mounted to the duct, and an actuator mounted to the support base and operatively connected to the damper vane for moving the damper between the open and closed positions, and wherein the support base functions to close an access opening in a side wall of the duct of sufficient size to permit insertion of the damper vane therethrough.

Abstract: The valve shaft passes through a journal bearing in the wall of the valve body to an actuating lever attached to the shaft on the outside of the valve body. This journal bearing is sealed by an arrangement of several parts to prevent escape of exhaust gases. These parts include a bellows and ceramic thrust washers. By making the valve shaft axis non-perpendicularly intersecting the axis of the valve body wall, the entire circumference of the valve blade can be sealed to the valve body wall when the valve is closed.

Abstract: A butterfly valve disc has a circular cross-section bore for receiving the end of a drive shaft which engages with a member non-rotatably located in the bore. The member is polygonal and preferably formed with twelve sides and edges, the edges biting into the internal surface of the bore to prevent rotation. The member preferably is of harder alloy than the disc to resist wearing and is formed with a slot extending perpendicularly to the plane of the disc to receive a corresponding tongue formed at the end of the shaft. This arrangement allows a small degree of play so that if the disc is subjected to pressure on one side and therefore bends, the torque required to open the valve is not increased. Alternatively wherein the disc (or another component) is not subject to such pressure the member may be integrally formed with the shaft.

Abstract: A valve of the type for controlling engine coolant flow to a heater core having a resilient butterfly valve formed of thermoplastic elastomeric material. The outer periphery is sufficiently resilient to absorb actuator overtravel in the seated condition. The butterfly has formed integrally therewith a central hub with torque-transmitting surfaces molded therein and a pair of oppositely disposed stiffeners extend outwardly from the hub in the central region of the butterfly. Assembly is simplified by placing the butterfly in the body and inserting a winged actuator shaft through journal holes in the body into the butterfly hub such that the wings on the shaft engage the torque-transmitting surfaces in the hub.

Abstract: A butterfly valve comprising a valve body, a throttle plate located within a throat of the valve body, and opposed projecting pins connected to the throttle plate and extending into two opposed bores of the valve body. At least one pin has an annular bearing surface. A spring urges either a thrust bearing against a needle bearing which in turn bears against the annular bearing surface or a needle bearing against the thrust bearing to bear against the annular bearing surface. This urges the throttle plate against an opposed thrust bearing which bears against the opposed projecting pin connected to the throttle plate to center the throttle plate within the throat of the valve body. A set screw can be provided to accurately position the throttle plate within the throat of the valve body. Preferably the throttle plate has tapered end sections to diminish turbulence within the valve throat.

Abstract: An industrial butterfly valve which incorporates a disc valve mounted upon a valve stem, the butterfly valve having a tubular housing, with a gasket lining the interior passageway through the housing, the gasket and tubular housing having apertures provided therethrough for pivotally mounting of the valve stem and its disc element, and a sleeve provided upon the valve stem and lining the gasket apertures to prevent leakage of any fluid material therethrough or from contacting and deteriorating the contiguous gasket.

Abstract: An exhaust tube having an internal butterfly valve is coupled to the exhaust end of a conventional exhaust pipe extending from an internal combustion engine. The valve plate is mounted for swinging about an axis offset from the axis of the exhaust tube. The valve plate is spring-biased to a normal position substantially obstructing the exhaust tube. At high exhaust flow conditions, the valve plate is automatically swung to an open position in which flow through the exhaust tube is essentially unrestricted. Under back pressure conditions, the valve plate swings oppositely but still constitutes a substantial obstruction to exhaust flow. Consequently, the valve automatically opens at high flow conditions and automatically closes at low flow and back pressure conditions for more efficient operation of the internal combustion engine.

Abstract: An improved stub shaft to disc connection for a butterfly valve is provided having a valve disc with a hub. The valve disc is adapted to be rotated between an open and closed position. A valve disc seat is adapted to engage the valve disc in the closed position. A shaft is joined to the valve disc to permit torque to be transmitted to the valve disc from a point remote therefrom. The shaft is joined to the valve disc by forming the valve disc with a portion of increased thickness (hub) relative to the main portion of the disc. The portion of increased thickness is formed at a point adjacent the circumference of the disc. A hole (bore) is then machined into the portion of increased thickness parallel to the disc. The bore consists of a single larger aperture contiguous with a plurality of smaller apertures, the plurality of smaller apertures, positioned at a point more distal the circumference of the disc than the single larger aperture.

Abstract: A ceramic valve assembly is housed in a recess formed in a metal pipe and is supported via gaskets by the metal pipes. Each gasket has a larger coefficient of linear expansion than that of the metal pipe. A clearance generated due to the thermal expansion difference between the metal pipe and the ceramic housing is absorbed by the large thermal expansion of the gasket so that no play is generated between the ceramic valve assembly and the metal pipe and the sealing force is maintained. Each gasket has beads constructed of spring material. An excessively large load does not act on the ceramic assembly because the beads are deformed to absorb the load.

Abstract: There is provided a valve damper which is pivotally suspended and may in its closing position cooperate with a seat, e.g., formed in a ventilating channel, and wherein an annular seal may be placed on the damper and/or seat. In order to achieve a smoke-tight closure of the damper, the latter is connected to a pivot shaft via resilient carriers, the attachment points thereof on the damper being displaced in relation to the axis of the pivot shaft.

Abstract: A butterfly valve disc has a circular cross-section bore for receiving the end of a drive shaft which engages with a member non-rotatably located in the bore. The member is polygonal and preferably formed with twelve sides and edges, the edges biting into the internal surface of the bore to prevent rotation. The member preferably is of harder alloy than the disc to resist wearing and is formed with a slot extending perpendicularly to the plane of the disc to receive a corresponding tongue formed at the end of the shaft. This arrangement allows a small degree of play so that if the disc is subjected to pressure on one side and therefore bends, the torque required to open the valve is not increased. Alternatively wherein the disc (or another component) is not subject to such pressure the member may be integrally formed with the shaft.

Abstract: The drive shaft is formed with a longitudinally extending groove and the wall of a blind bore formed in the valve disc for receiving the shaft is formed with a projection which fits in the groove by a punching operation. The mating parts are readily made by conventional metal forming techniques and there is no need to pierce the disc.

Abstract: A rotary throttle member for an internal combustion engine comprises a shaft and a butterfly valve member secured to a central length of the shaft. The shaft and butterfly valve member are single pieces of synthetic material. End portions of the shaft straddle the said central length. The central length has a uniform non-circular cross-section greater than that of the full end portion of the shaft situated on one side of the length. The shaft includes a cam for connection with and winding of a control cable, situated on the other end portion of the shaft. The butterfly valve member has a central hole of complementary cross-section of said central length and is fixed onto the central length.

Abstract: A servomotor actuated engine coolant valve with a plastic body and a thin resilient butterfly plate valve member formed of plastic material internally with a shaft hub drum having the motor shaft received therethrough for torque transmission to the butterfly plate. The butterfly plate is configured to have sufficient resiliency to absorb servomotor overtravel in the valve closed position.

Abstract: An industrial butterfly valve for use in a fluid flow line is provided having a tubular housing with a disc valve and stem mounted for pivotal movement within the flow passage found in the housing. The assembly employs a unique bolt retention component that functions to prevent back out of the bolts holding the disc to the stem and further functions to prevent leakage around the bolts. A resilient seat around the interior periphery of the flow passage provides a positive seal when the disc is rotated to a closed position the resilient seat having a pair of annular bias springs molded into the mounting edges so as to retain its shape and resist peeling or distortion upon assembly and disassembly in a flow line.

Abstract: A pipeline valve is provided which includes a valve body having a spherical bore with a cylindrical valve seat. The cylindrical valve seat is positioned along the centerline of the spherical valve body and can be machined in the valve body. Alternatively, the valve seat can be an elastomeric material which is inserted into the valve body. The butterfly valve disk is conical in shape. In one embodiment, the disk is constructed from two halves, fastened together, having a movable T-seal perimetrial surface.The T-seal is received by a groove recessed within the disk. Behind the T-seal, an elastomer or linear expander biasing member can be disposed to force the T-seal in a direction towards the valve seat. The valve disk is connected to a control shaft by an attachment assembly which allows for self-alignment of the disk. The control shaft terminates in a forked end having two legs which define an aperture corresponding to coupling pads on either side of the disk.

Abstract: A butterfly valve (30) in which an actuator (38) is secured to the plate (36). The actuator (38) is carried with the plate (36) when the latter moves. The plate (36) may be revolvable and translatable relative to the shaft (42). The actuator (38) may be used to open and adjust a pilot valve (94) secured to and carried with the plate (36), and to revolve or translate the plate (36) relative to the shaft (42) in order to vary hydrodynamic torque exerted on the plate (36).

Abstract: A method and device are disclosed for fitting a shaft-butterfly valve unit in a pipe formed by a butterfly valve body. The device comprises a frame receiving the pipe with its unit. It also comprises a first thruster for moving the shaft in a first direction as far as the first abutment position and a second thruster for moving the shaft in the opposite direction as far as the second abutment position. A sensor detects the abutment positions, and the gap (j) between the abutment positions is computed. The first or second motor is controlled for moving the shaft from the first or second abutment position by a distance equal to a predetermined fraction of the gap.

Abstract: A high temperature control damper for use in an air flotation dryer with built-in afterburner or any other high temperature environment. Two damper blades are mounted between high temperature bearings and rotate in an insulated housing. The inner ends of the damper engage in a ship-lap joint, and the outer ends of the damper engage against sealing flanges.

Abstract: There is disclosed a butterfly valve having a stem which extends through a disc rotatable within a seat about an annular hub to open and close the valve. The stem and disc have flat sides which engage one another in order to rotate the disc within the stem, and outer end of the stem is releasably retained in a bore through a neck on the hub.

Abstract: Disc-stem connection for a butterfly valve using interfitted slots on the disc and stem for mechanical connection. An oversize slot on the disc creates channels between the disc and the stem which allows deep penetration of a weld bead. Centralization of the stems within the oversize slots is effected by means of small spacers interposed between the stems and the slot edges. The spacers are small enough so that the necessary space created for the weld is not displaced.

Abstract: The invention is a butterfly-type check valve (8) wherein the valve plate (18) moves translationally relative to a pivot axis (90) and incident to its own rotational movement. The invention employs biasing means (102, 104, 108) for initiating movement of the valve plate when the latter is at a closed rotational position, thereby eliminating the need for a pilot valve.

Abstract: A butterfly-type check valve (8) in which a valve plate (18) moves translationally relative to a pivot axis (90) and incident to rotational movement (118) of the plate. The translational movement is effected by mechanical links (38, 40) which are pivotally secured to the plate and a support assembly (52, 54, 56, 76, 78). The translational movement is guided by two trunnions (30, 32) pivotally secured to the support assembly, and two rods (20, 22) rigidly secured to the plate and extending through the trunnions.

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 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 butterfly valve (30) is described in which the plate member (32) is in facing relationship with a hollow shaft (34) and is moved by pistons (50, 52) disposed in the shaft. The pistons (50, 52) are mechanically coupled to the plate member (32) by cam followers (58, 60) which ride along cams (40, 42, 46, 48) formed in the shaft (34) and plate member. The plate member (32) is capable of both revolutionary and translation movement relative to the longitudinal axis of the shaft (34) toward the end of minimizing the externally supplied energy required to operate the valve (30). The pistons (50, 52) collectively have a center of mass that coincides with the center of the duct (68) toward the end of minimizing vibrational effects.

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.