Abstract: An arrester system for arresting without substantial bounce a moving object, such as the arm of a billet stamper, is constituted by a housing mounting at one end a steel ball which is struck by the moving object. The housing also guides an axially movable steel cylinder which is normally in contact with the steel ball but is driven away from it on impact of the moving object with the ball. The housing further carries a hydraulic or resilient energy absorber which has a piston rod which extends parallel to the movement of the cylinder and which is struck by the cylinder when the latter is driven away from the steel ball. The ball and cylinder form an energy transforming device, the energy of the moving object being transferred via the ball to the cylinder, which in turn transfers the energy to the energy absorber in the direction of the piston rod. Energy transfer is effected without movement of the steel ball and without any substantial bounce of the object.

Abstract: A new and improved stencil-sheet holder includes a frame adapted to define a central open area over which a stencil-sheet is mounted so that the major part of its surface is suspended in air with sufficient tension to prevent the formation of wrinkles in the stencil-sheet. A novel support structure adjustable in the longitudinal direction is provided so that different size stencil-sheets can be readily accommodated in the apparatus. Removable support pins make it possible to support different styles of stencil-sheets.

Abstract: Method and apparatus for printing materials, wherein ink is applied to an intaglio matrix and then scraped off to such an extent that ink remains only in the depressions of the matrix. A printing pad having a surface which is normally repellent to ink is pressed onto the matrix such that ink adheres thereto in accordance with the pattern of the depressions of the matrix. The printing pad is then pressed against a material to be printed such that the ink on the printing pad is substantially completely transferred to the printed material.

Abstract: A composite structure for making printing plates and other surfaces in relief is improved by reducing the density of a polymer substrate thereby increasing the amount of material removed per unit of time by a given total amount of energy. The density of the polymer substrate is reduced by making it cellular or poriferous using expandable micro capsules made of thermoplastic shell and a nucleus of a liquified blowing agent.

Abstract: A nonelectrically initiated delay booster assembly includes a booster shell containing an explosive material, a cap well extending through one end of the booster shell into the explosive material, a nonelectric delay cap in the well and a detonating cord tunnel surrounded by a shock absorbing material affixed to the side of the booster shell or enclosed inside the booster shell. A signal carrier extends from a point within the cap to a point adjacent a detonating cord extending through the detonating cord tunnel, and a sensor member is affixed to that end of the signal carrier that is external to the booster shell in such a manner that it is in initiating relationship with the detonating cord extending through the detonating cord tunnel. A plurality of these boosters can be affixed to a single detonating cord downline when conducting multi-deck blasting operations.

Abstract: In a nonelectrically initiated delay booster assembly which includes a booster shell containing an explosive material, a cap well extending through one end of the booster shell into the explosive material, a detonating cord tunnel surrounded by a shock absorbing material affixed to the side of the booster shell or enclosed inside the booster shell and a detonating cord laced through the tunnel, there is provided a delay insert which consists of a sensor, signal carrier and nonelectric cap assembly for transmitting detonation from the detonating cord to the explosive material in the cap which cap is inserted in the cap well of the booster. The signal carrier extends from a point within the cap to a point externally of the booster shell and adjacent the detonating cord extending through the cord tunnel, and the sensor initiating member is affixed to that end of the signal line lying externally of the booster shell in such a manner that it lies in initiating relationship with the detonating cord.

Abstract: An elongated shuttle car is provided having a set of undriven rail wheels and a set of driven road wheels. The rail wheels are movable between a lowered position wherein they support the shuttle car and a raised position wherein the shuttle car is supported from the road drive wheels. The road drive wheels are independently driven by fluid drive motors, one of which is associated with each road wheel. The road wheels are disposed so as to permit movement of the shuttle car generally perpendicular to its longitudinal axis which is aligned with the rail bed. Hydraulic cylinders or jacks are utilized for raising and lowering the undriven rail wheels which are normally formed of steel. The rail wheels are supported in movable truck assemblies. The movable truck assemblies have an axle permanently attached thereto and a pair of rail wheels are attached to the ends of the fixed axle.

Abstract: Described is a lading harness support for use on flatbed transportation devices comprising a base which is anchored to the transportation device; at least a pair of parallel leg members attached to said base and extended therefrom and a rod-like anchor means extending longitudinally with respect to the base and spaced therefrom and fixedly attached to said leg members in an I-shaped manner. When the transportation device carries agricultural combines or other off-the-road vehicles, the lading harness support anchors the same thereto.

Abstract: A pallet having a rectangular shaped load carrying deck of generally uniform thickness. The deck is formed of several sheets of flexible wooden material with spring characteristics. The sheets of flexible wooden material are superimposed on one another and formed to be arcuate about a single axis. The sheets are glued together so as to constitute an arcuate structure substantially free from inherent tension forces in its unloaded condition and having sufficient elasticity to assume a substantially planar form under load. Supporting means are attached to the under convex side of the deck. The supporting means are arranged in a plurality of parallel rows extending in the direction of the single axis. One of the rows is located in the plane intersecting the axis and a line on the deck substantially corresponding to the central deck line. A second row of supports extend along the first outer edge portion of the deck and a third row of supports extend along a second outer edge portion of the deck.

Abstract: A dining room table to facilitate serving food including inner, intermediate and outer concentric sections. The intermediate section is rotatably mounted on a pedestal to pass food around the table. The outer section includes a plurality of arcuate segments abutted about the intermediate section to provide a dining surface. The inner section supports a center piece and is fixed to the pedestal within the intermediate section.

Abstract: The invention covers a protective device in the outer area of a room, for instance a banking hall of a financial institution, with a bullet-proof door, which can be locked, leading into a room, the locking mechanism being operated in conjunction with a release device.

Abstract: An antishoplifting system for premises in which goods are sold and in which signal transmitters are affixed to the articles of goods. Each of the transmitters has a continuously effective first signal emitter which cooperates with a detector at the entrance or exit of the premises to signal removal of an article with the transmitter thereon. In addition, each transmitter comprises a self-contained second signal emitter, which requires no external energy source and is activatable upon removal of the transmitter from the goods to emit a signal. Receivers on the premises detect this signal and produce an output indicating the location of the source thereof.

Abstract: An incinerator system and method wherein pieces of solid waste, such as fragments of wood, are conveyed in such a fashion as to become disposed within a fluidized bed of an incinerator vessel. Preferably the solid waste particles are caused to be somewhat homogeneously dispersed within the fluidized bed. The solid waste particles may be "pre-dried" or moisture may be added to the particles prior to deposition in the fluidized bed for optimum results, depending upon circumstances. In one embodiment, the fluidized bed is situated above an air delivery chamber at the bottom of the vessel and supports combustion of the solid waste particles in the fine granular material comprising the fluidized bed. The fine granular material is supported by a perforated plate. The air delivery system channels high temperature air into and up through the fluidized bed until operating temperature is reached and so channels ambient air thereafter.

Abstract: This invention relates to incinerators for the disposal of urban waste. More particularly, it relates to incinerators of the type comprising a rotary furnace of highly heat-resistant steel, having a horizontal axis of rotation and comprising a drying chamber and an incinerating chamber; drive means for rotating the furnace; charging means for feeding refuse to the drying chamber; a burner projecting into the drying chamber; afterburner means for recombusting any incompletely burned refuse leaving the incinerating chamber and for ridding combustion gases of solids; means for supplying preheated comburent air to the furnace; and means for cooling and exhausting the combustion gases.

Abstract: A digging and planting machine is provided, having a tubular digging and planting tool movable being ground-contacting and ground-elevated positions, and having an open digging and planting tip end; closure means movable between a first position closing off the open end for digging a hole and a second position exposing the open end for delivery of a plant from the planting tool into the hole; and means for compacting earth around the plant after planting.

Abstract: A toy sewing machine capable of sewing in zig-zag patterns comprising cam body having plural cam faces, a vertically movable pin arranged to engage with any one of the cam faces of the cam body, and means for connecting said pin with a needle holding rod. Said means comprises a freely rotatable lever of "L" shape urged in one direction by a torsion bar spring, one end of said lever having the pin penetrated therethrough, and a link pivotally attached to the other end of said lever.

Abstract: A pressure regulating module for a sewing machine, the module supporting a pressure regulating cam, and a cam follower mechanism for cooperative engagement with the cam, the cam follower mechanism having a laterally extending ear impressed with a spherical surface impinging against a platform on a plunger slidably received in a bore in a presser bar of the sewing machine, the plunger being in abutment with a compression spring also received in the bore. The spherical surface, plunger, compression spring and presser bar are in substantial alignment when the module is assembled to the sewing machine frame. The cam includes a darning position where little or no pressure is applied to the presser bar, by which assembly to the sewing machine frame may be facilitated.

Abstract: A power-operable hand tool for folding back upright flange portions at the edges of sheet material, which comprises a jaw for supporting the underside of the sheet during said folding operation, an operating jaw pivotally mounted about an axis extending parallel to the axis of the support jaw drive means for causing operative pivoting of said operative jaw, said drive means being connectable to a source of motive power therefor, wherein the operative jaw is formed at one end with a recessed portion terminating at its periphery in a lug portion capable of engaging over the edge of an upright flange portion to be folded back, a main pressing surface extending from said recessed portion.

Abstract: A device for cleaning the bottom of a boat or the like while the boat is afloat in the water comprising a pair of rods pivotally connected at corresponding end, a cleaning member pivotally connected to the end of one rod and an adjustable clamp for setting a desired angular position between the rods. Stabilizing members assist in aligning the cleaning member with the surface of the boat.

Abstract: A mechanical coupling for connecting together two buoyant members, such as pontoons, to make a buoyant structure. The mechanical coupling comprises vertical grooves in the pontoons. A pair of spaced apart plates partially cover the edge of the grooves. A key member in the shape of an I-beam fits with its web between the plates of a pair of pontoons so that its flanges hold the two pontoons together. Wedge shaped members attached to the I-beam and to the plates further act to wedge and lock the pontoons together as a unit.

Abstract: A water ski rope handle of molded plastic construction with floatation cavities in the handle portion and rope anchoring end caps rigidly secured to the ends of the same which provide for mounting of the rope with the knots in the ends of the rope being recessed to captivate the same and with the rope being angled from the handle to minimize fraying or wear thereof.

Abstract: An indicator device mounted on a vacuum cleaner housing which is under the influence of the pressure differnce between the inlet and outlet of a dust or dirt collector unit of the vacuum cleaner. The outer surface of the indicator device has markings that are continuously visible, and which show the amount of accumulated dust and dirt filling in the dust collector, at any given time.

Abstract: A digital display indicator for a television tuner utilizes a tape or other record medium having each of the television channel numbers disposed thereon in a seven-segment type font. A mechanism is provided for moving the tape past a display window to simulate a seven-segment digital display. In an alternative embodiment, the channel numbers may be displayed on one or more circular discs.

Abstract: In a system for treating articles automatically while the articles are in a stopped treating position, an improved triggering circuit activates the treating device. In one embodiment, multiple cans are simultaneously spray coated by a corresponding number of spray coating guns. An indexing type conveyor with pockets for holding cans moves cans along the same path until a group of pockets holds cans in spraying positions proximate a group of coating guns. When the conveyor has moved a sufficient distance to bring the group of cans to the proper spraying positions, the conveyor is stopped for a predetermined period of dwell time sufficient to complete the spraying operation before the conveyor is again moved. A separate proximity sensor for each spraying position determines the presence or absence of a can in each spraying position independently. Any given spray gun is activated only if the sensor associated with that spraying position has sensed the presence of a can for some predetermined interval of time.

Abstract: An apparatus for dispensing predetermined amounts of lining material into cap shells, particularly of the deeply recessed type, includes a conveyor including a passage for conveying cap shells at predetermined speeds, an extruder provided above and along the shell-conveying passage for extruding predetermined quantities of a lining material through a discharge passage, a blade fitted adjacent to the exit end of the discharge passage and rotatably across it for cutting the lining material, and a drive for rotating the blade in response to the conveying of the cap shells. The drive is adapted to rotate the blade at a non-uniform speed in response to the speed of shell conveyance so that its speed gradually decreases as the exterior end of the blade in its radial direction approaches the shell-conveying passage, and gradually increases as it departs from it, whereby collision between the tip of the blade and the cap shells can be completely avoided.

Abstract: A large capacity system for hog production in a controlled environment provides, within an inflated air dome housing, a base from the central area of which rises a multi-tier hog finishing structure. At generally base level a relatively wide area about the tiered structure includes a first or breeding and farrowing zone adjacent the inside perimeter of the housing dome and a second or nursery feeder pen zone between the first zone and a third zone under the tiered structure. The third zone provides an initial growing and observation area to receive pigs from the nursery feeder pen zone and from which the pigs are transferred at the proper intervals to the tier levels for finishing to market weight. This new animal movement program corresponds directly to advantageous proportionate management activity and observation requirements and maximizes these activities at the most pleasing area of the structure.

Abstract: Cage structure for poultry and the like comprises a number of cage rows mounted on A-frames in pyramided, stepped back, A-shaped, elevational array. Each cage row includes a bottom/back member and a top/front member joined together to form a row of cages of rectangular cross section. Each cage row is tipped forward to incline the cage bottom so as to urge eggs laid in the cages to roll forward into an egg collecting trough at the cage front. The bottom element of the bottom/back member forms at least a portion of the top of the cage row next below. A feeder trough forms a portion of each cage front.

Abstract: This disclosure pertains to a harness for animals, such as dogs, utilizing unitary leash grasping means secured to a portion of a harness, grasping the chest of the animal. A neck encircling portion is removably secured about the neck of the animal, supporting the chest grasping portion of the leash. A waist encircling band is secured along the length of the leash and is adapted with a buckle at the uppermost regions thereof. The animal may be restrained by forces exerted on the chest as opposed to windpipe choking forces when the leash is maintained in a staionary position.

Abstract: The present invention relates to a water supply pipe for a steam generator.The supply pipe comprises the following elements in a substantially horizontal portion (3) thereof:A lower baffle plate (4) defining or limiting an upper opening (7),And an upper baffle plate (5) defining or limiting a lower opening (9) and being disposed upstream of the lower baffle plate with respect to the normal flow direction of the water.The horizontal edge (8) defining the upper opening is disposed higher than the horizontal edge (10) defining the lower opening.As a result, the two baffle plates form between them a hydraulic barrier, which, when the water supply is cut off or reduced, prevents or substantially limits the passage of steam coming from the generator.

Abstract: An apparatus and method for improving the combustion process of an internal combustion engine is disclosed. A prechamber containing a combustible mixture is designed to generate a torch eminating thereform upon ignition; the torch is controlled to extend and penetrate deeply into the main combustion at a predetermined orientation without contact with the chamber walls. The swirling flame front of the sustained torch produces superior mixing with the unburned combustible mixture in the main combustion, particularly of a rotary engine. The prechamber is located outside the epitrochoid chamber of the rotary engine; in a nonstratified charge mode of this invention, the prechamber serves to receive a portion of the main chamber inducted charge during the compression cycle, which may lean and difficult to ignite in the main chamber. In the prechamber, concentrated hot walls and a localized spark facilitate ready ignition, which in turn permits generation of a torch therefrom.

Abstract: An internal combustion engine with greatly reduced emission of pollutants includes a piston having a piston chamber communicating through orifices with the working chamber of the cylinder and an annular balancing chamber communicating with the working chamber through balancing slots when the piston is between 20.degree. to 30.degree. from its bottom center position. Breathing holes are provided at the opposite end of the balancing chamber. Air from the balancing chamber flows into the working chamber in response to the vacuum therein during the intake stroke, flows from the working chamber into the piston chamber during the compression stroke, and from the piston chamber into the working chamber during the power stroke to stratify the combustion process and inhibit the emission of hydrocarbon and carbon monoxide pollutants. Some exhaust gases are admitted to the balancing chamber during the exhaust stroke to be readmitted to the working chamber during the next intake stroke.

Abstract: An improvement in a rotary vee device that includes relative rotational and reciprocal motion between the interior walls of the cylinder and the exterior walls of the pistons characterized by each piston having first flow areas defined on its periphery and a first fluid flow passageway; each of the first fluid flow passageways in communication with the interior of its respective cylinder above its respective piston and with its respective first flow areas; and each cylinder wall having intake ports and discharge ports located at predetermined locations.

Abstract: A process and apparatus are disclosed for improving the efficiency of combustion in a spark ignition four cycle internal combustion piston engine. After a fuel-air charge is inducted into the cylinder(s), gas is injected at moderate pressure into the cylinder at a level below the spark plug, while the pressure in the cylinder is low. Preferred gas injection timing is from about the time the piston completes the intake stroke until the piston is about half-way through its compression stroke. Air and/or engine exhaust may comprise the injected gases. Valves and conduit for controlling the injection are provided as a sub-assembly which can be fitted to existing engines and use the engine camshaft for correct actuation.

Abstract: A carburetor having a main intake passage for a lean mixture and an auxiliary intake passage for a rich mixture is provided with a choke valve in each passage. A control mechanism for operating the two choke valves includes a lost-motion connection so that the main choke valve is at the first to be moved toward closed position, for cold starting of the engine. For colder temperatures, both choke valves are moved toward closed position, and for very cold starting conditions, both choke valves are moved to fully closed position. The control mechanism may be manually operated or it may be automatic under the control of a bimetal element. When the engine on being started reaches a state of complete firing, with stable RPM, both choke valves are opened to predetermined pull-down angles.

Abstract: A throttle positioner having a structure that a lever drivingly connected to a rotary shaft of a throttle valve is positively driven in a throttle opening direction by a lever driving element which is driven in said direction by a diaphragm means to establish a throttle positioner pre-set opening when the throttle positioner is to be actuated.

Abstract: The position of a fuel nozzle of a variable size venturi carburetor is adjustable with respect to the venturi orifice in dependence on climatic conditions such as an ambient temperature and/or atmospheric pressure. An additional air delivery passageway controllable by an electronic air/fuel ratio control system in dependence on an exhaust gas sensor signal is connected with the fuel nozzle.

Abstract: The recirculation rate estimation means comprises three temperature sensors to respectively measure temperatures of intaken air, recycled exhaust gas and resulting mixture, and an analog computing unit to produce a signal representing an actual recirculation rate based on the temperature data and predeterminate specific heat values of the respective gases.

Abstract: An archery bow includes a pair of bow limbs projecting from opposite ends of a handle member, each eccentrically mounting pivotal cam members at its outer extremity. Each cam member comprises a larger diameter cylindrical cam element and a smaller diameter cylindrical cam element eccentrically joined together and having a common pivot axis which is eccentric with respect to both cam elements. A bow string for projecting an arrow comprises a working stretch and a pair of separate end segments, one detachably connected to each end of the working stretch. Each end segment extends from the working stretch and is wrapped partially around its associated larger diameter cam element, then passes through a diametric bore in the cam member to the opposite side of the smaller diameter cam element, wrapping further around the smaller diameter cam element, and extending therefrom to a connection with the opposite bow limb.

Abstract: A trigger assembly for launching the projectile of a spring loaded weapon such as a harpoon, cross-bow or the like is disclosed having a detent adapted to engage the rear end of the projectile. The detent swingable about an axle fixed to the butt stock and a spring member is supported within the butt stock to engage said detent. The forces created by the projectile acting on the detent, cause said spring member to curve into a reactive position, the curvature of the spring in the reactive position is limited and a trigger member is provided for displacing the spring from its curved position into a position releasing the reactive force on said detent.

Abstract: A freestanding fireplace comprising a firebox and a spaced, outer housing has a primary draft to ventilate the firebox and secondary drafts to cool the firebox. The primary draft flows into the flue from the firebox through a conduit or pipe which fits within and is spaced radially from the flue. Secondary drafts flow through passages defined by the space between the firebox and the outer shelf and enter the flue around the outside of the primary draft pipe. The flow of the primary air draft creates a reduced pressure effect which draws air through the secondary draft passages, thereby cooling the firebox and the flue. Smoke spillage prevention means are also provided.

Abstract: The window unit is formed of a frame and of glass sheets arranged in spaced parallel relationship so as to form an air space between adjacent glass sheets; the frame is defined by top and bottom members and a pair of side members. The top and bottom frame members each have laterally spaced longitudinal portions forming channels and individually receive a major portion of the upper and lower marginal edges of the glass sheets.

Abstract: A heat collector and radiator for allowing the absorption of lower atmosphere radiation by the maximizing of the surface area capable of absorbing the diffuse radiation. A plurality of closely spaced tubular elements are disposed in parallelism with relatively narrow web portions interconnecting the adjacent tubular elements and in tangential relationship therewith. The structure is unitarily formed from a polymer material admixed with carbon black or like additive. A header means at each opposite end of the tubular elements/web portions communicates therewith. The structure is selective in the respect that it has an emissivity lower than absorptivity, and is less effected by the incident angle.

Abstract: A solar heating system includes a solar collector comprising a continuous length of copper tubing coiled into a helical array of closely adjacent turns and supported within a sealed housing. The outer turns of the array are fabricated of tubing having a greater diameter than the tubing which forms the inner turns of the array, and the total length of the larger diameter tubing in the array is greater than that of the smaller diameter tubing. The relationships beween the tubing diameters and lengths are selected to achieve a desired flow rate and temperature rise for the overall array. The array is supported within the housing by copper sheets which also operate to eliminate moisture condensation within the housing.

Abstract: Solar heating apparatus that includes a solar panel having a generally rectangular box type frame that is open at the front, glass panes mounted on the frame to close the front opening and provide a dead air space, a plurality of horizontally elongated, generally rectangular tubular channels mounted with the top wall of a lower channel in abutting relationship with the bottom wall of the next higher channel, a water inlet opening through one end of the uppermost channel, a water outlet opening through one end of the lowermost channel, conduits interconnecting the channels to provide a liquid flow path serially through the channels from the uppermost channel to the lowermost channel, a heat storage reservoir, lines including a pump for pumping liquid from a heat exchanger in the storage reservoir to the panel inlet and return the liquid from the outlet to the heat exchanger, control mechanism for operating the pump in response to temperature changes in the panel, and a heat transfer system for transferring hea

Abstract: A syringe shield having an inner generally cylindrical shell formed of plastic material. The shell has an elongated slot extending longitudinally therein and is open-ended at its rear end and narrows radially inward at its front end to form a tapered portion. A generally cylindrical body formed of radiation-shielding material is proportioned such that its inner surface conforms generally to the outer surface of the inner shell. The body has an elongated slot therein which is aligned with the slot in the inner shell. An outer shell, formed of plastic material, conforms to the shape of the outer surface of the body and has an elongated slot aligned with the slots in the inner shell in the body. An elongated optically transparent radiation shielding member is proportioned to fit in the elongated slot in the body. In the preferred embodiment of the invention the inner shell has a plurality of flexible plastic protrusions on the inner surface thereof.

Abstract: An incentive inhalation device which induces respiratory exercise and which is inexpensive, safe and easy to handle and operate. The device includes a container having a plurality of flow measurement chambers which are vertical when the device is in its upright position. In each chamber is housed a flow rate indicator, such as a light-weight article and ball, that normally rests at the bottom thereof. The bottom of each chamber is open to surrounding atmosphere and the top of each chamber is open to a common passageway. In operation, the patient or user withdraws air from the common air passageway and chambers. When the patient achieves a precalibrated flow rate the indicators sequentially rise to the top of each chamber. To prevent disruption of air flow into the passageway and surprise or shock to the user, means are provided in the last chamber to prevent the indicator from closing the last chamber to the common air passageway.

Abstract: A splint or other body-support device adapted to fit around or along a body portion of a human or animal subject is formed with a closed compartment containing capsules or the like of two mutually reactive substances capable of hardening or foaming in situ to form a hardenable mass stabilizing the shape of the device. The device may comprise an envelope of a flexible material which may be kneaded or deformed to rupture the capsules and mix the reactive substances.

Abstract: Breathing apparatus is provided for use under water which comprises a connection device such as a helmet, mask, or the like and a breathing circuit in communication with the connection device. The breathing circuit includes a carbon-dioxide absorber and an expansible gas chamber, and, in operation, provides a first operating period wherein the breathing circuit is closed and a breathing gas is caused to circulate in the breathing circuit until the oxygen concentration of the circulating breathing gas is reduced to a predetermined value and a second operating period, which alternates with the first, wherein the used breathing gas is released to ambient and a fresh gas, the quantity of which is substantially independent of the depth of the user under the water surface, is applied to the breathing circuit.

Abstract: A respirator for infants wherein air is delivered to a nasal catheter at a preset pressure during the inspiratory phase, the flow being maintained in an amount sufficient to maintain the pressure regardless of leakage, while pressure and volume are monitored during the expiratory phase through a bellows which operates a recording device and can be adjusted to maintain a desired minimum terminal pressure at the end of the expiration; also the method of effecting respiration by means of such a respirator or equivalent devices.

Abstract: Ventilator having an inhalation phase and an exhalation phase in its operative cycle for use with a source of gas under pressure. A demand flow accelerator is responsive to the pressure of the gases in a breathing head assembly and provides additional gases to the breathing head assembly when the pressure of the gases in the breathing head assembly falls below a predetermined pressure. A sensor is also provided responsive to the pressure of the gases in the breathing head assembly for supplying gases to the breathing head assembly when the pressure of the gases in the breathing head assembly falls below a predetermined value to cause the patient to exhale against a substantially constant positive airway pressure. An additional sensor is also provided which is sensitive to the airway pressure being sensed for bleeding gases from the breathing circuit when pressure greater than a predetermined pressure are reached.