Abstract: A turbocharger comprises a center housing, and a shaft positioned therein having a first end and a second end. A turbine housing is attached to one side of the center housing and has a turbine wheel disposed therein that is coupled to the first end of the shaft. A first variable geometry member is disposed within the turbine housing between an exhaust gas inlet and the turbine wheel. A compressor housing is attached to another side of the center housing opposite the turbine housing, and includes a compressor impeller disposed therein. The compressor impeller is coupled to the second end of the shaft. A second variable geometry member is disposed within the compressor housing, and is interposed between an air outlet and the compressor impeller. An actuator assembly is disposed within the turbocharger and is connected to both of the variable geometry members to provide simultaneous actuation of the same.

Abstract: A shaft seal for use with a unison ring actuator crank is disposed within a center or bearing housing of a variable nozzle turbocharger to reduce leakage of hot exhaust gas from an adjacent turbine housing. A seal ring is disposed within the turbine housing backing plate which has two differently sized diameter sections. The seal ring is positioned within a relatively larger diameter opening section and has an inside diameter sized to permit independent rotation around the shaft and an outside diameter sized to cover a relatively smaller diameter opening section. A relieved back surface directed towards the center housing such as a conical back surface that is tapered axially inwardly moving radially from the outside diameter to the inside diameter of the seal ring provides the desired sealing while not adding to the operating friction of the crank.

Abstract: An exhaust-gas turbocharger for an internal combustion engine has a turbine having a variable turbine geometry for the variable setting of the effective flow inlet cross section to the turbine wheel. The exhaust-gas turbocharger has a compressor which is connected to the turbine via a shaft. The variable turbine geometry can be adjusted by means of a regulating device between a closed position and an open position. To compensate for wear, a stop limiting an end position of the variable turbine geometry is provided, and the position of this stop can be set in a variable manner.

Abstract: A turbocharger with variable geometry turbine inlet nozzle employs a rotating unison ring for actuation of multiple vanes. A crank arm engages a slot in the unison ring to convert linear actuator motion into rotation of the unison ring. A crank pin having a rectangular tongue adapted to be received in the slot and a circular body received in an aperture in the crank arm reduces contact stresses between the crank tongue and unison ring slot. The crank pin is retained in the crank arm by the unison ring and center housing flange of the turbocharger.

Abstract: A turbocharger with variable geometry turbine inlet nozzle employs a rotating unison ring for actuation of multiple vanes. A crank arm engages a slot in the unison ring to convert linear actuator motion into rotation of the unison ring. A crank pin having a rectangular tongue adapted to be received in the slot and a circular body received in an aperture in the crank arm reduces contact stresses between the crank tongue and unison ring slot. The crank pin is retained in the crank arm by the unison ring and center housing flange of the turbocharger.

Abstract: A vane adjustment mechanism, for controlling the quantity of exhaust gas including a base unit having an inner base unit and an outer base unit. The inner base unit (2A) has first and second flanges, and is forced into the outer base unit (2B). A plurality of U-shaped indentations (2c) are spaced at regular angular intervals and each indentation extends from the first flange (2a) to the second flange (2b), so that the U-shaped indentations form vane shaft holes for accommodating the vane lever units (3) when the inner base unit is inserted into the outer base unit to block the U-shaped indentations in such a way that the vane lever units are free to rotate. A link plate (4) has U-shaped indentations, in which protrusions of the vane lever units (3) engage, all along the circumferential edge of the link plate.

Abstract: Disclosed is a producing method of an exhaust gas vane blade for superchargers of motor vehicles. The vane blade consists of a pivot part and a blade part with a streamlined section, which are integrally formed with each other. The vane blade is made of a heat resisting steel. The diameter of the pivot part is larger than the thickness of the blade part. The method comprises a multi-step cold-forging of a blank material of the above steel.

Abstract: This invention is developed to solve the problems described above. The object of this invention is to provide a vane adjustment mechanism to control the quantity of exhaust gas, which will have fewer components and a simpler design, which will operate in a stable fashion, and which will be extremely durable. The base unit comprises an inner base unit having first and second flanges, and an outer base unit 2B into which the inner base unit 2A is forced. A plurality of U-shaped indentations 2c spaced at regular angular intervals on the inside surface of the inner or outer base unit from the first flange 2a to the second flange 2b, so that the U-shaped indentations form the vane shaft holes to accommodate the vane lever units when the inner base unit is forced into the outer base unit to block the U-shaped indentations in such a way that the vane lever units are free to rotate.

Abstract: A guide blade-adjusting device for a turbocharger has an adjusting ring that is guided in a simple manner on the guide blade carrier plate. The adjusting ring comprises noses projecting in the axial direction. At least one the noses radially guides the adjusting ring on the guide blade carrier plate.

Abstract: A shaft seal for use with a unison ring actuator crank is disposed within a center or bearing housing of a variable nozzle turbocharger to reduce leakage of hot exhaust gas from an adjacent turbine housing. A seal ring is disposed within the turbine housing backing plate which has two differently sized diameter sections. The seal ring is positioned within a relatively larger diameter opening section and has an inside diameter sized to permit independent rotation around the shaft and an outside diameter sized to cover a relatively smaller diameter opening section. A relieved back surface directed towards the center housing such as a conical back surface that is tapered axially inwardly moving radially from the outside diameter to the inside diameter of the seal ring provides the desired sealing while not adding to the operating friction of the crank.

Abstract: A vane and post arrangement for a variable geometry turbocharger employs vanes having a hole in a first end surface receiving a post extending from a surface of the nozzle in the turbine housing. A second end surface on each vane incorporates an extending tab which is received in a respective slot in a unison ring for rotation of the vanes on the posts upon movement of the unison ring.

Abstract: A nozzle drive mechanism is provided for a link plate 112, which can operate all nozzle vanes smoothly and synchronously. The nozzle vanes 104 supported in such a way that the nozzle vanes are free to rotate between open and closed positions on nozzle shafts. The nozzle vanes are connected to levers which correspond to the nozzle shafts so as to rotate along with the levers. Each boss at the end of each lever 114 functions as a shaft which is parallel to the nozzle shaft. The shafts (bosses) in the nozzle vanes engage in oblong holes in the link plate in such a way that they are free to swing, and are thereby connected to the link plate. A declined straight or curved centerline which runs through the oblong hole to the oblong direction, extends at a given angle with respect to the radius of the link plate.

Abstract: An internal combustion engine having an exhaust-gas turbocharger is provided. The exhaust-gas turbocharger includes a variable turbine geometry that allows for a greater range of use. The exhaust-gas turbocharger is used as a throttling device to dimension the combustion-air quantity delivered to the engine. The variable turbine geometry can be adjusted in such a way that the direction of rotation of the rotor of the exhaust-gas turbocharger is reversed. The intake pressure in the air inlet of the internal combustion engine is set as a function of the direction of rotation of the rotor.

Abstract: An exhaust-gas turbocharger for an internal combustion engine has a turbine having a variable turbine geometry for the variable setting of the effective flow inlet cross section to the turbine wheel. The exhaust-gas turbocharger has a compressor which is connected to the turbine via a shaft. The variable turbine geometry can be adjusted by means of a regulating device between a closed position and an open position. To compensate for wear, a stop limiting an end position of the variable turbine geometry is provided, and the position of this stop can be set in a variable manner.

Abstract: A variable geometry turbocharger employs multiple vanes in the turbine inlet with a unison ring and integral cast wall in the turbine housing forming the nozzle walls. The unison ring incorporates actuation slots receiving tabs on the vanes for opening the closing the nozzle area upon rotation of the unison ring. An integral electrohydraulic actuator rotates the unison ring through a rack and pinion driven crank shaft with direct position feedback to the spring biased variable current solenoid via a cam on the crank shaft.

Abstract: A turbine disposed in a water passageway includes a hub and associated runner blades. Each blade comprises an inner edge and a distal outer edge, a leading edge and a trailing edge separated by a water directing surface. Each blade is rotatable relative to the hub about a blade rotational axis. The water passageway includes a spherically-shaped discharge ring that conforms to the outer edges of the blades to improve certain turbine parameters such as cavitation, efficiency, flow disturbance, and fish survivability. The turbine hub may also include a spherically-shaped outer surface in a region swept by the inner edges of the blades when the blades are rotated from maximum to minimum pitch, as well as seals attached to the inner edges of the blades. The hub may also be associated with blades in which the chord is reduced in the root region of the blade.

Abstract: A turbine installation having reduced inner and outer gaps comprises a water passageway and a turbine runner disposed in the passageway downstream of a discharge ring. The turbine runner includes a hollow hub having spaced apart inner and outer surfaces and a longitudinal axis and a plurality of runner blades. Each blade comprises a hydrofoil having an inner edge and a distal outer edge, a leading edge and a trailing edge separated by a water directing surface. Each blade is pivotally connected to the hub about a rotational axis extending in a direction generally perpendicular to the longitudinal axis so that its inner edge is proximate the hub. Each blade is rotatable between a maximum pitch position and a minimum pitch position. The discharge ring has a spherical configuration cooperable with the outer edge of each of the blades to reduce an outer gap formed between the outer edge of each of the blades and the passageway.

Abstract: A housing for a double spiral circulation pump includes a spiral housing and a multipartite rib. The spiral housing defines a flow channel. The multipartite rib is disposed in the housing to divide the flow channel. The multipartite rib includes at least two rib parts spaced from each other to define a gap therebetween.

Abstract: A radial-flow exhaust-gas turbocharger turbine is provided with a row of adjustable guide blades which are rotatable via adjusting shafts mounted in a casing. The guide blades are each provided with sealing discs on their longitudinal sides running at right angles to the adjusting-shaft axes. The diameter of the sealing discs is a multiple of the thickness of the guide blades. The sealing discs which are located on the side remote from the adjusting shafts form bearing points for the guide blades in the casing.

Abstract: A blade for a Kaplan turbine has substantially linear touching lines for contacting, in the closed position of the guide blade array, adjacent guide blades, the contact lines being linear or curved and running generally parallel to the pivot axis of the blade. The trailing side of the blade extends progressively inwardly and with a progressively increasing distance from the touching line on the trailing side.

Abstract: A radial-flow exhaust gas turbocharger turbine includes a row of individually adjustable guide vanes, each guide vane mounted on a rotatable shalt supported in the turbine casing. A chord of each guide vane is not greater that a largest diameter of the shaft on which the guide vane is mounted. When viewed in the axial direction, a profile of each vane lies completely within a radially outer contour of the associated shaft. This permits the design of a one-piece adjustable unit formed of a guide vane, a rotatable shaft, and a pivoting lever. The adjustable unit can be inserted into the casing or removed from the casing as a single unit to facilitate installation and maintenance.

Abstract: The invention provides a regulating system (23) for controlling the heating of the gases on the downstream side of the regulating system, attenuating the aerodynamic noise produced by the gyratory flow on the downstream side of the directing vanes (24) of the regulating system and facilitating the endoscopic inspection of the blades and vanes of a compressor (3) owing to the provision of a throughway passage (27) in the regulating system (23), and in particular a throughway opening in at least one directing vane (24).

Abstract: The invention relates to a compressor provided with an impeller having a rotating shaft for the purpose of compressing air, and an air inlet having a circular cross-section centered on the rotating shaft so as to provide air for the impeller. Further provided are a plurality of movable vanes respectively pivoted in the inlet near the outer circumference of the circular cross-section, a mechanism for tilting these vanes, and a mechanism for causing a specific movable vane to project further downstream than the other movable vanes. When a circular flow is set up in the air inlet by the movable vanes, Karman vortices are produced from the rear ends of the vanes, and when the phases of these vortices combine together, noise is generated. A specific movable vane, the rear end of which projects further downstream than those of the other vanes, disrupts and interferes with the phase combination of the Karman vortices produced by the other vanes, and thereby prevents noise.

Abstract: Wicket gates and axial flow or mixed flow runner blades for a hydraulic turbine with the wicket gates arranged in a generally circular array around a central axis and with the gates pivotal about pivot axes parallel to the central axis. Each of the wicket gates is provided with a trailing edge shaped to present a discharge angle which varies from a small discharge angle at the bottom of the gate to a large discharge angle at the top of the gate. The discharge angle at any point along the length of the trailing edge is preselected such that water flow having a known radial velocity vector at the trailing edge will have a constant circumferential velocity vector along the length of the trailing edge. The shape of the runner blades is related to the shape of the wicket gates such that the whirl value for the fluid flow exiting the runner blades is between about zero and a value that is less than the change in whirl from the inlet to the exit of the runner apparatus formed by the runner blades.

Abstract: A method and apparatus for eliminating vortex whistle noise in a radial-to-axial compressor intake uses a plurality of vortex-disturbing tabs mounted to the trailing edges of inlet guide vanes and extending into the flow path between adjacent vanes. The tabs are mounted to the guide vane so that the tab is always perpendicular to the guide vane, regardless of the vanes angular position.

Abstract: A hydroelectric installation includes a hydraulic machine connected vertically below an electric machine by a shaft, in a concrete installation pit. A guide vane assembly of the hydraulic machine is operated by a motor-driven operating unit which projects below the hydraulic machine in a lower working space of the pit. The shaft has a thrust bearing which bears down against the upper cover of the hydraulic machine and thereby substantially cancels upward hydraulic force exerted on that upper cover. In the installation procedure, the outer casing, speed ring and upper cover of the hydraulic machine are installed first, so that the hydraulic machine can be assembled downwardly in the lower working space concurrently with upward assembly of the electric machine in an upper working space of the pit. This shortens installation time.

Abstract: The invention relates to a method to calculate optimum wicket gate positions based on only the initial face-to-face readings comprising the steps of measuring the initial gate openings, determining an optimum unit opening, and rotating each gate to the optimum opening. The method results in a one time adjustment that is more accurate and faster than conventional methods.

Abstract: This invention relates to an improvement in an apparatus for directing the flow of water from the penstock to the vanes of a hydraulic turbine, generally referred to as a wicket gate, and a method for making the improved wicket gate. The improved wicket gate comprises a rotatable planar body made either of a high-strength plastic material or metal, onto which a viscoelastic material is affixed. The improvement lies in the application of the viscoelastic material to the rotatable planar body in such a way that the viscoelastic material becomes an integral component of the rotatable planar body. This improvement extends the maintenance life cycle by reducing marine growth, erosion and pitting caused by cavitation.

Abstract: A turboexpander-generator system employing a housing with a rotatably mounted shaft oriented vertically with a turboexpander associated with the upper end of the housing and shaft, a generator associated with the housing and shaft below the turboexpander and a lubricant pump located at the lower end of the housing and shaft. The lubricant pump controls an actuator valve which controls the variable inlet nozzles to the turboexpander. Thus, a speed control system is achieved through use of the lubricant pump pressure. A seal gas separator is provided with two ports located in the turboexpander exducer at positions of different pressure. High pressure is used to provide a seal between the bearings and the turboexpander. Low pressure is directed to the area of the sump of the pump to enhance continuous lubricant return. A self-priming mechanism causes a reservoir to be charged during pump operation with return of the lubricant to the sump when the pump is off.

Abstract: Nozzle shafts and a nozzle drive mechanism are disposed on the side of a bearing casing and a compressor whose temperatures are lower than that of a turbine, and elements slidable in the radial direction of the turbine wheel are eliminated from the nozzle drive mechanism so that any adverse effects due to oxidization at high temperatures and slide wear can be eliminated. Thus durability and reliability of the device can be improved.

Abstract: A variable-displacement turbine includes a turbine wheel disposed in a housing, a scroll passage defined in the housing around the turbine wheel, at least one fixed vane and at least one movable vane disposed between the scroll passage and said turbine wheel and arranged alternately in the direction of rotation of the turbine wheel, the fixed and movable vanes jointly defining a variable nozzle which has an opening adjustable in response to angular movement of the movable vane. At least one of the fixed vane and the movable vane has a bypass passage defined therein in bypassing relation to the variable nozzle.

Abstract: An adjusting device of a compressor includes guide vanes (2) arranged in the form of a ring around a longitudinal axis (4), which vanes are in each case connected fixedly in terms of rotation to pivot pins (8) and are pivotally mounted in the housing (46). Two-armed cranks (10) are connected fixedly in terms of rotation to the pivot pins (8), cranks (10) neighboring each other in circumferential direction being linked to each other by means of coupling links (24, 26). With a lower overall volume and low use of materials, a jamming, in particular in view of thermal expansions and production tolerances, is to be avoided. For use with a radial-flow compressor, it is proposed to arrange the cranks (10) and the coupling links (24, 26) in an annular space (52) which neighbors the discharge port, into which space the pivot pins (8) parallel to the longitudinal axis (4) protrude with their free ends.

Abstract: The turbine comprises orientable vanes or flaps (10b, 10a) respectively forming the distributor and a movable part of the volute of the turbine. These vanes are disposed in such manner that (a) the intrados (15) of one thereof directs the fluid which travels thereover in a path which is no longer in contact with the other, (b) the extrados (14b) of one of the vanes is travelled over by a fluid current which feeds the other vane and (c) the extrados (14a) of the other of the vanes is travelled over by a fluid current entering directly into the turbine only between its shaft (11a) and its trailing edge (13a). The turbine has application in the supercharging of engines of motor vehicles.

Abstract: A turbocharger comprising a central housing which has at one end a radially outwardly extending annular flange. A backplate is arranged between the center housing and the turbine wheel. The outer peripheral portion of the backplate is held between the annular flange and the turbine housing. Nozzle vanes are arranged in the exhaust gas inlet passage formed between the backplate and the turbine housing. Bush insertion bores are formed in the backplate and the annular flange. Bushes are axially and movably inserted into the bush insertion bores. The axial movement of the bushes is restricted by stop means. The shafts of the nozzle vanes are rotatably supported by the bushes.

Abstract: A turbocharger having a variable nozzle vane assembly to be used in association with an engine. A plurality of pivotable vanes are mounted between the turbocharger backplate and unison ring on one side and an annular side wall, independent of the turbine housing on the other. Each vane includes a drive pin which pivots the vane in response to rotational movement of the unison ring.

Abstract: A variable-capacitance radial turbine has a swingable tongue member which is swingably mounted in an inlet throat portion of a scroll fluid passage of the turbine and which is swingable on a pivot shaft parallel to the turbine wheel axis. The right and left scroll side walls are formed with right and left seat surfaces, and the tongue member is formed with right and left sealing surfaces on both sides. The right and left seat surfaces and sealing surfaces are not perpendicular to the turbine wheel axis, and they are so shaped that when the tongue member is in a predetermined limit position, the right and left sealing surfaces are in contact with the right and left seat surfaces respectively so as to seal the clearances between the tongue member and the scroll side walls over the full length of the tongue member.

Abstract: A diametrically opposed pair of radially inwardly directed vortex-disturbing tabs are secured to a compressor intake assembly to eliminate vortex whistle therein.

Abstract: In a device for regulating the air supply of an internal combustion engine supercharged by a turbo-compressor unit driven in rotation by the engine's exhaust, the intake of the rotating compressor is controlled by an intake regulation (or gating) system capable of reducing the compressive effect of the rotor of the compressor. Control elements of said regulation (or gating) system are connected with the accelerator linkage so as to close the regulation (or gating) system and reduce the compressive effect to the maximum degree when the accelerator moves toward the idling position of the engine.

Abstract: A diametrically opposed pair of radially inwardly directed vortex-disturbing tabs are secured to a compressor intake assembly to eliminate vortex whistle therein.

Abstract: A series of airfoil cross-section equidistantly spaced normally parallel vanes are disposed linearly across the mouth of an induction housing port which lies on an essentially flat plane non-intersecting with the axis of rotation of a turbo compressor wheel. A control mechanism moves the vanes upon the compressor tending to surge so that each of the vanes is moved through an angle different from the preceeding one, whereby the air flows passing between the vanes are deflected and converge upstream of the compressor wheel and swirl theretoward in the form of a single flow to impinge on the blades of the wheel with a uniform and reduced angle of incidence.

Abstract: Disclosed is a multistage hydraulic machine system which comprises a multistage hydraulic pump/pump-turbine including a highest-pressure stage having movable guide vanes with variable opening of water path arranged round a runner and a lower-pressure stage or stages having fixed guide vanes with fixed opening of water path arranged round a runner or runners, and a control unit for controlling the operation of the multistage hydraulic pump/pump-turbine, whereby the opening of the movable guide vanes is controlled by the control unit so that such opening is larger than that of the fixed guide vanes for a large-flow normal operation of the pump/pump-turbine and smaller for a small-flow normal operation.

Abstract: The invention comprises a rotary fluid handling apparatus having first and second coaxial bodies mounted for relative axial movement therebetween and having respective opposed radially facing annular surfaces. The bodies may be, for example, the stator of a turboexpander or compressor and a relatively rotatable clamping ring for a plurality of adjustable blades. A first seal including a sealing ring is disposed between and seals between the annular surfaces, and the apparatus defines a first pressure zone which communicates with one axial side of the seal. The first body has a first stop engageable with the sealing ring to permit the force exerted on the sealing ring by the pressure of the first zone to be transmitted to the first body.

Abstract: A hydraulic turbine wicket gate operating assembly including an eccentric pin having a separate hexagonal spacer attached provides a novel means for turning the eccentric pin and fixing it from rotation beyond a desired point. With the arrangement, a single gate operating ring can be utilized to permit all of the gates to move in unison and to provide for the simultaneous closing of each gate against each adjacent gate.

Abstract: A hydraulic turbo-machine incorporating wicket gates for purposes of controlling and closing down the flow of working fluid through the machine is provided with an annular ring gate selectively operable to take up any operating clearance between the casing and the adjacent axial edge of the wicket gates. This arrangement makes it practical to incorporate relatively large initial clearances between the wicket gates and the fixed machine structure, so as to leave provision for natural contraction of such clearances during the life of the machine, due to shrinkage of the concrete or other expected or unexpected causes. The operation of the annular ring as a piston within a cylinder is facilitated utilizing penstock water or oil under pressure as the motivating fluid.

Abstract: The invention provides a turbocharger for use with an internal combustion engine and includes a compressor for supplying air to the engine and a turbine for receiving driving exhaust gas from the engine. The turbine has a shaft integrally attached thereto with which the turbine rotates. The compressor is fitted on the turbine shaft for rotation with the turbine. The shaft is rotatively supported by ball bearing assemblies such that the compressor and turbine are overhung to one side of the bearing assemblies with the turbine separated from the bearing assemblies by the compressor. As a result of this arrangement, the bearing assemblies are removed from the turbine and the intense heat to which the turbine is subjected. This makes possible the use of limited lubrication for the bearing assemblies. The use of ball bearings also provides better control over the radial and axial movement of the turbine and compressor and permits reduced blade tip clearances.

Abstract: Advance diffuser for an axial blower having an impeller of large diameter received in a substantially circular housing and an axis extending in a given direction, includes a suction box formed with an intake opening through which a medium is drawable by suction in a direction substantially perpendicular to the given direction of the blower axis, a plurality of swirl vanes mounted on respective, mutually parallel shafts in the suction box, the suction box having a pair of mutually opposing parallel walls wherein the shafts are rotatably mounted, a pair of casing surface sections mutually connecting the parallel walls and tangentially merging with and surrounding the substantially circular outline of the impeller housing, the suction box having another wall facing toward the impeller and formed with a suction opening, the parallel shafts whereon the swirl vanes are respectively mounted being disposed along an arc surrounding part of the suction opening, the arc having end points mutually connectible by a secant

Abstract: A gas turbine engine of the two shaft free turbine type has a first gasifier turbine for driving a compressor to supply air to a combustor for combustion with fuel to produce motive fluid for driving the compressor turbine and a second free wheeling power turbine. An air brake with a compressor impeller directly coupled to the power turbine has an inlet and an exhaust and a close coupled iris throttle assembly for regulating the inlet flow of air into the compressor to obtain maximized power turn down ratios without aerodynamic instability.

Abstract: A plurality of threaded studs are rigidly connected to the turbine head cover about each wicket gate shaft. A packing ring is adjustably connected to the threaded studs to hold the wicket gate shaft packing between the head cover and the wicket gate shaft. A thrust ring is also adjustably attached to the threaded studs to provide thrust clearance adjustment between the thrust ring and the wicket gate.

Abstract: A turbo-machine such as a hydraulic turbine and/or pump-turbine is provided with a combined scroll case distributor wherein the customary stay ring of the scroll case is dispensed with and the distributor integrated with the scroll case, the edges of the distributor that define the distributor slot being held in spaced relation by a series of bolts, on which may be mounted the wicket gates of the machine. The arrangement results in a marked reduction in size and weight of the scroll case components, with potential benefit in the characteristic form of the machine performance.

Abstract: A device to produce vehicle braking from a two-shaft gas turbine engine including an air brake with a centrifugal impeller on the power turbine shaft, the impeller having blades forwardly turned at the impeller exit through an angle greater than sixty degrees for absorbing energy from the power turbine shaft thereby to control power transfer to an output shaft. The system includes a variable inlet control assembly to throttle inlet air flow to the air brake impeller so as to regulate the amount of power absorption from the power turbine shaft.