Abstract: Apparatus and systems for a fire resistant rated fenestration including curtain wall systems for multiple story buildings capable of withstanding a seismic load. Fire resistant panels are mounted in a fire resistant mullion where the mullion may be one element, or may have an inner structural shell and an outer shell. A barrier of fire resistant material is disposed between the inner and outer shells. A sealer compound or a fire resistant compressible filler seals the space between the mullion and the fire resistant panels. The inner structural shell member is connected to an elastic panel fastener that is connected at its opposite end to fire resistant panels. The fastener allows the fire resistant panels to move in response to a seismic load without damage to the mullion or panels.

Abstract: This invention relates to a space-dividing wall panel system which includes components which are compatible with various types of wall panels and furniture components therefor. These components include a connector bracket having multiple inserts for supporting furniture components thereon, and an interface assembly also is provided which is compatible with various wall panel systems. A spiral cable manager also is provided for supporting cabling within the wall panels.

Abstract: A connector for connecting a horizontal member with at least one vertical member in an interlocking manner includes plastic body in the shape of a cylinder, having one flat side which extends parallel to a longitudinal axis of the cylinder. A pin projects outwardly near a top end in of the plastic body, in a radial manner. A through hole is provided in the plastic body through which a securing screw can be threaded into at least one vertical member against which the connector is disposed.

Abstract: A Dyligomer is disclosed.

Abstract: A wooden floor truss/foundation wall combination is not made entirely from all-weather wood. In one embodiment, opposed end studs of untreated lumber rest upon treated lumber resting upon a footing just inside and near the bottom of the concrete foundation stem wall. In another embodiment, the end stud bottoms rest in a pocket depression in the footing lined with an environmental barrier to protect the stud bottom from dampness in the concrete footing. In another embodiment, an elongated floor joist member extends to the foundation wall to rest on a pad on the wall or in a pocket depression in the wall that is lined with an environmental barrier, or to hang on a joist hanger connected to the wall, and frame webbing extends down from the floor joist member to an environmentally-lined corner between the top of the footing and the bottom of the inside foundation wall.

Abstract: A post cap assembly having a body including a generally vertical side defining an interior volume. A one locating member projecting into the interior volume and having a stop formed thereon for positioning the post cap on a support. Furthermore, the post cap having an upper portion to selectively receive a light source. The light source reflected down over and substantially illuminating only the sides of the post cap through apertures selectively formed in eaves on the tops of the sides.

Abstract: A straw bale wall vent box is provided in a wall joinery system comprising a lower member, a substantially planar top member, and a plurality of rebar disposed through the top member and a bottom side of the lower member. The lower member can further include insulation, a drainage floor sloping downwardly from an exterior side, and a trim piece extending from the bottom side towards the plaster screed. In some embodiments the trim piece joins the plaster screed. In those embodiments in which the trim piece joins the plaster screed, both sides of the lower member can each include at least one aperture. Additional embodiments are directed to a straw bale wall vent system comprising a plurality of wall vent boxes placed side by side so that the first and second sides of adjacent vent boxes are substantially in contact.

Abstract: A tile assembly and method of installing tile is shown where each tile has an underside, and a support board is adhered to the underside of one ore more tiles. One such tile assembly is connected to another tile assembly by a tongue and groove arrangement, where each tile assembly is not cemented, screwed or otherwise adhered to the floor. The space between the tiles is filled with a flexible group made of rubber silicone, white sand and dye. The tiles may be made of any suitable material such as of ceramic, stone, marble, granite, vinyl composition tile (vct), brick, or other composite materials that use mortar to set the material to a floor or sub-floor.

Abstract: Boards, whether or of wood or man made materials, have downwardly converging sides in the manner of an inverted trapezoid to create a downwardly expanding space between such boards when used for decking, porches, balconies, walkways and the like. The downwardly expanding space between adjacent boards reduces the likelihood of clogging by debris and the like to which the decking, etc. is expected to be subjected.

Abstract: Provided herein are blocks useful in the construction of walls and other structures. The blocks include in their design features which render them to be interlocking, and which provide for a wall constructed from the blocks to include a plurality of horizontal and vertical channels that are adapted to receive reinforcing rods (“rebar”). Once a two-dimensional network of rebar is disposed in the interior of such a wall constructed from blocks according to a preferred form of the invention, a castable concrete may be poured into the wall and caused to exist in the spaces between the rebar and the blocks of the invention. By such construction, a wall comprising concrete in its interior that is reinforced in two dimensions is provided, wherein reinforcement in the third dimension is provided by the interlocking feature of the tops and bottom portions of blocks in adjacent rows with one another.

Abstract: A framing assembly system for steel building that substantially reduces assembly time while maintaining excellent strength and mechanical integrity. In fabricating this type of building, foundation assemblies are first placed in concrete footings at a precise location in both the horizontal and vertical planes. Once the concrete has cured, columns are placed over the foundation assembly and bolted into place using pre-drilled holes in the columns and foundation assembly, thereby eliminating the difficult task of holding the columns erect while at the same time trying to precisely position the column in the horizontal and vertical planes. Trusses are connected to the top of the columns by means of bolts passes through pre-drilled holes.

Abstract: A support assembly comprising first and second parts, each part comprising a pair of spaced parallel elongate members (12, 14, 62), and a support arrangement (16) extending between the elongate members (12, 14, 62), the first and second parts being mountable together with the planes thereof inclined relative to each other and first ones of the elongate members (12, 62) aligned adjacent and parallel to each other such that the apex defined by the meeting of the first elongate members (12, 62) provides a first support surface, and opposite sides of the other elongate members (14, 62) define second spaced support surfaces.

Abstract: A hemp building material for creating a reinforced structure utilizing hemp fibers. The hemp building material includes an elongate structure having a plurality of bast fibers contained within the elongate structure. The bast fibers are orientated substantially parallel to the longitudinal axis of the elongate structure. The bast fibers are preferably positioned within the lower portion of the elongate structure to provide tensile resistance to the elongate structure during the supporting of a vertical load. The elongate structure may have various configurations and may be constructed of various materials such as but not limited to plastic and composite materials.

Abstract: A building construction framing system utilizes studs and joining members which are respectively extruded and molded from a composite plastic/wood flour material. Along its length, each stud has a central web with transverse outer edge flanges and an intermediate transverse flange that defines with the outer edge flanges a separated pair of longitudinally extending lateral pockets on each side of the web. A series of first studs are arranged in a spaced apart, parallel relationship with their opposite ends abutting parallel, spaced apart second and third studs. The joining members are positioned at the opposite ends of the first studs, are recessed in the lateral pockets of the first, second and third studs, and are secured to their adjacent studs using suitable fastening members.

Abstract: The structural wooden joist described comprises an elongated lower chord, an elongated upper chord and an openwork web structure joining the chords and consisting of a series of connector members formed of inclined branches and adhesively secured to the lower and upper chords. Each branch of a connector member is formed of at least two planks having contiguous sides adhesively joined to one another. The connector members define a series of triangular openings in the web structure.

Abstract: The structural wooden joist described comprises a lower chord, an upper chord, a plurality of connector members spaced along the joists and extending between the upper and lower chords, a plurality of plates attaching the connector members to the lower and upper chords and a laminated panel structure mounted at each end section of the joist. Each panel structure extends from an opposite end of the upper/lower chords to adjacent a first of the plurality of attachment plates and defines an uninterrupted surface which is formed of a series of elongated vertical planks secured edgewise to one another whereby the joist has opposite ends which are trimmable to provide one of reduced width.

Abstract: The present invention is method and resulting assembly for applying a flexible liner to the outer surface of a pre-cast concrete walled container to be buried in an earthen excavation.

Abstract: A forming panel and method for using the same in construction of self-sustaining concrete wall structures is provided wherein a flexible barrier element is provided along a margin on the forming panel for impeding the flow of water and fine particles of a concrete mix pour past the barrier element. The margin may be along the perimeter edge of the forming panel or along an opening interior to the perimeter of the forming panel. When located near the perimeter, the flexible barrier element may be positioned in a slot extending parallel to the margin and located in the frame. When located near an interior opening, the barrier element may be provided on a reinforcing member positioned around the opening or on a door which shifts to improve access through the opening during placement of forming ties or the like.

Abstract: A manufacturing facility and method for assembling a composite box structure on a railway car underframe are provided. The composite box structure may be defined in part by an exterior metal surface, interior side stakes attached to the exterior metal surface, foam insulation disposed between the side stakes and attached to the metal surface and at least one layer of reinforced plastic material forming an interior surface. The composite box structure preferably includes a pair of end walls, a pair of side walls, a floor assembly and a roof assembly. The composite box structure may be assembled on a railway car underframe to form a temperature controlled boxcar or on insulated boxcar.

Abstract: A method of installing differently colored roofing shingles to create the appearance of a substantially random colored pattern. The method includes the selection of at least two colors of roofing shingles. The shingles are installed in a plurality of rows on a roofing substrate in a repetitive pattern. Advantageously, the method creates a visually aesthetic roof at a desirably low cost.

Abstract: A stiffener is provided for reinforcing a hollow structure having a pair of spaced walls with a pin extending across the walls. The stiffener includes a carrier member with a layer of expandable polymer which creates a structural foam when the polymer is later expanded. The stiffener could comprise a horseshoe shaped laminate shaped to fit over the pin of the hollow structure so that when the polymer is expanded it forms a structural foam intimately bonded to the pair of spaced walls.

Abstract: A sleeve used to wrap items such as potted plants or comestibles. The sleeve has a closed curved bottom. The sleeve may also have an expansion element such as a gusset, pleats, random folds or elastic material for enabling the lower portion of the sleeve to conform to the outer and bottom surfaces of the pot to provide a decorative cover about the pot. The sleeve optionally has a detachable upper portion.

Abstract: A method for transporting and displaying a floral grouping utilizing a shape sustaining floral holding material and a sheet of material. The method includes the steps of forming the sheet of material about at least a portion of the floral holding material with a forming device such that an upper end of the floral holding material remains substantially uncovered, and thereafter securing the sheet of material about the floral holding material with a band.

Abstract: A form, fill and seal packaging machine for forming, filling and sealing a carton, molds a closure directly onto the carton. The machine includes a carton erection station adapted to receive a carton in a generally flat form and to erect the flat form carton into a tubular form defining an internal carton region. A direct injection molding station has an internal mold tool and an external mold tool. The internal mold tool is configured for receipt within the internal carton region and the internal mold tool and the external mold tool are configured to receive and clamp the carton therebetween. The direct injection molding station further includes a polymer injection system for injecting polymer from a location external of the carton to the internal mold tool. The closure is directly molded in place on the carton. A mold tool set, a method for carrying out the molding and a closure molded thereby are also disclosed.

Abstract: A method of covering a pot wherein the cover is a flattened sleeve which comprises a base portion tapered to fit a pot and may have a skirt having an edge and having a lower end having excess material therein for forming a bottom. The cover may be bondingly connected to or crimped about the pot.

Abstract: An apparatus for packaging flexible-pouch packaged goods into cartons, trays, or the like is disclosed. An infeed section receives the packages from a source, orients the packages, and presents them to a picking device. The picking device has at least one picker head which contains a plurality of grabbers. The grabbers clutch the pouches, translate them to the tray or box loading station, then deposit the pouches in a composite motion which enables the pouches to be laid down in a space efficient and visually pleasing shingled manner. The process is controlled by a control unit programmable for a variety of product packaging configurations. The apparatus and process are especially suited for use with stand-up type or gussetted pouches.

Abstract: A method and apparatus for forming a tubular package is disclosed. A longitudinally advancing strip of film material is guided about a mandrel so as to form a tubular body. As the film advances, margins of the film at the longitudinal edges are guided together into a fin and the fin is guided against the tubular body portion. The edge margins are then welded to each other and to the tubular body portion to form a tube closed cylinder. Individual packages may be formed and filled using conventional form, fill and sealing equipment.

Abstract: A screw capper 1 includes a capping head 6 which grips a cap 5, a servo motor 7 which rotates the capping head, a voltmeter 10 which measures the torque of the capping head, an encoder 11 which detects the rotational angle of the capping head, and a control device 8 which controls the servo motor. In the screw capper, when whether rotational fastening is acceptable is to be determined during the rotational fastening, the measured value of the encoder is measured from a predetermined measurement starting point until a rotational fastening completion point, and if the measured rotational angle is in the range of an acceptable decision angle which is set in advance, it is determined that the rotational fastening has been acceptably performed, whereas if the measured rotational angle is not in the range of the acceptable decision angle, it is determined that the rotational fastening is unacceptable.

Abstract: An empty bag supplying apparatus used in a continuous conveying type bag-filling packaging machine in which the empty bag supplying apparatus receives empty bags and transfers these empty bags to gripper pairs of the bag-filling packaging machine that are moved continuously at a constant speed. The empty bag supplying apparatus includes downward-facing bag holding members and a reciprocating movement mechanism. The bag holding members hold the upper portions of bags. The reciprocating movement mechanism causes the bag holding members to reciprocate along an arc-shaped path and keeps the empty bags held by the holding members to be parallel to the direction of movement of the gripper pairs during the reciprocating motion. In a bag transfer region established in the arc-shaped path path, the speed of the bag holding members holding the empty bags is equal to the moving speed of the gripper pairs.

Abstract: A bitless bridle for humanely, physiologically and effectively restraining and controlling a horse or other animal at rest and at exercise comprises an elongated strap which includes a center piece at the poll, and two crossover straps at the sides, attachable to a pair of reins providing a direct link between the centerpiece and the reins. The crossover feature of the bitless bridle provides for persuasive, but non-painful, pressure to be applied to the whole of the opposite side of the head of the horse, from poll to chin or for rapid alternate pressure to be applied to both sides of the head. The centerpiece may include a plurality of holes for receiving studs for applying painless pressure on regions of special acuity at the poll and behind each ear of the animal, or may receive a separate sleeve which includes the studs in order to apply pressure over areas of special acuity.

Abstract: In a dry air filter for internal combustion engines of utility vehicles having an outlet for the dust separated in a preliminary separator stage, compressed air is delivered to the outlet, at least intermittently, and in order to produce an ejector action to keep the outlet and optionally the dust discharge valve closing off the outlet free of dust, is blown in the direction of the dust discharge valve. Preferably, surplus compressed air already to hand from an on-board compressed air generating system is used for this purpose. In order to improve the cleaning action, the compressed air is delivered into the outlet via a nozzle.

Abstract: There is provided a process for trapping particulate matter in a gas stream exiting a combustion equipment comprising providing a combustion equipment with one or more exits for exhaust gases, each exit connected to one or more ducts, and placing at least one particulate trap in each duct, wherein the particulate trap is removable and/or replaceable while the combustion equipment is online.

Abstract: A pickup reel for a harvester. The harvester includes a harvesting platform including a frame having a front edge and a cutter bar extending along the front edge. The pickup reel includes a reel support supported by the frame, a first shaft rotatably supported by the reel support and extending along an axis transverse to the frame, an arm extending radially from and being rotatable with the first shaft, a second shaft supported by the arm and being generally parallel to and radially spaced from the first shaft, the second shaft being rotatable relative to and rotatable with the arm, and a plurality of tines supported by the second shaft for rotation with the second shaft, each of the plurality of tines having a tip, the tips being movable along a tip path during rotation of the first shaft.

Abstract: A walk-behind power unit is configured to detachably mount a variety of work implements to perform a corresponding variety of operations from a single power unit. The power unit includes an implement mounting mechanism that is pivotable about a generally vertical pivot axis corresponding to the power output shaft of the engine on the power unit. An attached work implement can be moved laterally to change the operating characteristics through pivoting the implement to either side of a normal direction of travel. An landscape edger implement can be mounted so that the width of cut of the cutting disk is varied as the edger implement is pivoted. A mower implement can be attached so that the cutting path of the mower blade is offset laterally as the implement is pivoted, thus permitting the mower to mow around obstacles offset to the side of the direction of travel.

Abstract: A crop lifter for a harvesting machine reaping system with a bed plate (1) and projecting reaping fingers (2) has an elastically bendable support bar (5) with a first end (6) and a second end (7). The first end (6) is adapted to be retained on the bed plate (1). A grain lifter is connected to the second end (7) of the support bar (5). A holder (10), which has legs (15, 16), projects from the face of the support bar (5) facing the grain lifter (8). The holder (10) is adapted to receive the reaping finger (2) between the legs (15, 16). A holding means is adapted to support the reaping finger (2) in a direction towards the support bar (5). The support bar (5) includes an area with a bend (13), which opposes the portion adapted to receive the reaping finger (2) taken up by the holder (10). The portions (18, 19) on both sides of the bend 13 enclose an angle opening towards the grain lifter (8).

Abstract: In a reheat gas turbine engine for power generation, fuel is burnt with compressed air from a compressor in a first or primary combustor, the combustion products are passed through a high pressure turbine, the exhaust of the high pressure turbine is then burnt together with further fuel in a reheat combustor to consume the excess air, and the exhaust of the second combustor is passed through a lower pressure turbine. Excess air is supplied to the first combustor, thereby enabling so-called “lean burn” combustion for production of low levels of pollutants in the exhaust of the engine. Some turbine components of the turbines, e.g., blades or vanes, are cooled by cooling air supplies tapped off from the compressor.

Abstract: A gas turbine (5) according to the invention, which comprises a main combustion chamber (10), a cooling system for air cooling of at least the guide vanes (26, 29) and guide rings (28, 38) of various stages (25, 27) of the gas turbine (5), and a main gas passage, also includes a further combustion chamber (34), which is arranged downstream of the main combustion chamber (10) as seen in the hot-gas main direction (H). The cooling air (15) used to cool a stage (25) of the gas turbine which is arranged upstream of the further combustion chamber (34) is fed into this further combustion chamber (34). In this context, it is particularly advantageous for the cooling air (15) used to cool the various stages (25, 27) of the gas turbine (5) to be fed for combustion. This makes it possible, inter alia, to increase the output of the gas turbine (5) without having to increase the supply of fuel.

Abstract: A method is provided for using high concentrations of hydrogen peroxide to drive a turbine (20′) in a turbopump fed rocket engine (12′). The method includes the steps of: (a) receiving fuel into a fuel rich pre-burner (50); (b) receiving high concentrations of hydrogen peroxide into the pre-burner (50); (c) converting the fuel and hydrogen peroxide into a fuel rich gas; and (d) passing the fuel rich gas through a turbine (20′), thereby using high concentrations of hydrogen peroxide to drive the turbine. Thus, by utiliizing a fuel rich pre-burner (50) that operates at a very low mixture ratio, the drive gas for a turbine (20′) can be maintained at moderate temperature levels.

Abstract: A bypass gas turbine engine having an intermediate structural casing positioned between a primary flow path and a bypass flow path, and configured between a low pressure compressor and a high pressure compressor. The engine further having a bleed device arranged to deflect a portion of a gas flow from the low pressure compressor toward the bypass flow path. The bleed device includes an annular cavity defining a manifold situated upstream the intermediate casing and opening along the outer wall of the primary flow path, a plurality of conduits positioned along the intermediate casing, a plurality of tubes configured around the high pressure compressor and connecting the conduits to the bypass flow path, and at least one flow regulating valve disposed along the interior of each of the plurality of tubes.

Abstract: A catalyst deterioration detecting device of the invention has exhaust emission purifying catalyst on an exhaust passage of an internal combustion engine and air-fuel ratio sensors provided upstream and downstream of the exhaust emission purifying catalyst, respectively, and detects the deterioration of the exhaust emission purifying catalyst based on the outputs of the air-fuel ratio sensors. An index characteristic value of catalyst deterioration is calculated from the outputs of the air-fuel ratio sensors, a time-lapse changing ratio of the calculated index characteristic value of catalyst deterioration is calculated, and the deterioration of the exhaust emission purifying catalyst is determined based on the calculated time-lapse changing ratio.

Abstract: An exhaust emission control system having a nitrogen oxide adsorber and a desulfating device, and a method for desulfating a nitrogen oxide absorber. The desulfating device is managed so as to establish an oscillatingly rich and lean exhaust gas composition during a respective desulfating operation, and contain an oxygen accumulator downstream from the nitrogen oxide adsorber. The nitrogen oxide adsorber is effectively desulfated by way of a corresponding desulfating method, and released sulfur compounds are thereby simultaneously oxidized. The exhaust emission control systems can be utilized, for example, with a motor vehicle internal combustion engine.

Abstract: The present invention is provided with an NOx catalyst 17 provided in the exhaust passage of an internal combustion engine capable of lean burn and adapted to release and reduce absorbed NOx by a reducing agent, a reducing agent supplying means 19 provided in the exhaust passage on the upstream side of the NOx catalyst 17, a load detecting means for detecting the load of an internal combustion engine 1, and a reducing agent addition control means for controlling the reducing agent addition period and the reducing agent addition interval on the basis of the load of the internal combustion engine 1. The addition period and the addition interval for the reducing agent are controlled taking into account, for example, the degree to which reducing agent adheres to the wall surface in the exhaust passage depending on the velocity, temperature, etc.

Abstract: A diesel powered vehicle is provided with an SCR system which uses an external reducing reagent to convert NOx emissions in a manner which accounts for the effects of NOx transient emissions on the reducing catalyst. Actual NOx emissions produced by the engine are filtered using a variable NOx time constant in turn correlated to the reductant/NOx storage capacity of the reducing catalyst at its current temperature to account for changes in the SCR system attributed to NOx transient emissions. Catalyst temperature is filtered using a variable catalyst time constant corresponding to current space velocity of the exhaust gas to account for changes in the catalyst temperature attributed to NOx transient emissions. The reductant is metered on the basis of the filtered, corrected NOx concentration applied at a NSR ratio based, in turn, on the filtered, corrected reducing catalyst temperature.

Abstract: An apparatus and method of use with internal combustion engines, such as used for land vehicles, for the on-board recovery and purification of water. The source of water is from the vehicle's exhaust, where it is collected by condensation. The water recovery system consists of a device for cooling the exhaust so as to condense out the water, such as a counter-current flow heat exchanger in combination with a chiller (a refrigerant-cooled heat exchanger), which cools the exhaust below its dew point. Exhaust condensate is collected at the outlet of the chiller. These cooling devices may be coupled with the vehicle's air conditioning system. The condensed water then flows through the water purification portion of the present invention.

Abstract: A power plant and method for the generation of power from flowing air utilizes a generally vertically extending duct having an inlet open to atmosphere at an elevation above an outlet. A spray system is mounted adjacent the inlet for spraying droplets of a predetermined amount of water into the air causing the air and droplet mixture to become cooler and denser than the outside air to create a down draft of fluid within the duct. A power system mounted adjacent the outlet recovers energy from the downdraft of fluid passing through it. The predetermined amount of water sprayed is greater than the amount of water that would theoretically and potentially evaporate in the air throughout the entire elevation over an unlimited time period using fresh water droplets. The power plant can also be synergistically combined with desalination systems and aquaculture.

Abstract: A hydraulic system, particularly suitable for use in a work machine, is provided with a hydraulic pressure source. A first hydraulic load is associated with a first load function. A second hydraulic load is associated with a second load function. An independent metering valve assembly includes a plurality of independently and electronically controllable valves. The independent metering valve assembly includes an inlet fluidly coupled with the pressure source, a first outlet fluidly coupled with the first hydraulic load, and a second outlet fluidly coupled with the second hydraulic load. The hydraulic system is configured such that the independent metering valve assembly may operate and drive multiple hydraulic load functions.

Abstract: An apparatus and method for diagnosing mechanical problems in turbocharged engines. In its preferred embodiment, the apparatus consists of a boot that is coupled to a turbocharge system—preferably at the air inlet thereof. The apparatus further includes a source of air pressure that may be delivered to the turbocharge system, a first pressure gauge to measure the pressure of the air that is being delivered, and a second pressure gauge to measure the pressure of the air within the turbocharge system. Under pressure, and with the engine off, the turbocharge system can be inspected for leaks. In addition, under pressure, the operation of turbocharge system components—such as the wastegate valve/diaphragm and the boost sensor—can also be inspected.

Abstract: The invention provides a method and apparatus for recovering work from a gas turbine and providing a cooled inlet air, a refrigeration capacity and that may use a common working fluid in both systems . More importantly the system provides a working fluid for more efficient heat transfer by maintaining a supercritical working fluid in an energy recovery system, for example, recovery of waste heat from a gas turbine exhaust.

Abstract: A segmented radiant gas burner features wide modulation of thermal output simply by the independent control of fuel gas flow to each burner segment. The burner also features a porous fiber burner face, preferably having dual porosities, and a metal liner positioned to provide a compact combustion zone adjacent the burner face. The segmented radiant burner is ideally suited for use with gas turbines not only because of its compactness and broad thermal modulation but also because only the flow of fuel gas to each burner segment requires control while the flow of compressed air into all segments of the burner remains unchanged.

Abstract: A gas turbine which is capable of operating in more than one pressure mode. The gas turbine, which may include a single fixed spool, multiple fixed spools, or a combination of fixed spool(s) and a free turbine, can operate in a positive pressure mode, a transatmospheric mode, or a subatmospheric mode. Valving is provided to control the particular pressure mode of operation in response to system requirements and to switch between pressure modes as required.