Abstract: An improved closed-loop hydrostatic transmission system is provided of the type including a pump (11), a motor (13), and a pair of conduits (15 and 17). The system includes a main control valve (43) and a charge pump (23) which is the sole source of make-up fluid to the closed-loop system and the sole source of control fluid for varying the pump. The system includes a power limiting means comprising first and second pressure relief valve means (75 and 77) operable to provide fluid communication from whichever side of the closed-loop is at high pressure to the system reservoir whenever system pressure exceeds the predetermined maximum pressure. The motor is adapted to transmit drive torque to a reversible load (37) of the type having a known inertia and a predeterminable time of deceleration from maximum speed operation in one direction to a standstill condition.

Abstract: A drive mechanism for driving a shaft in unison with a wheel. The drive mechanism includes a plurality of slave pistons and a like plurality of master pistons. Each slave piston is paired with a master piston to establish a plurality of paired pistons. A cam is operatively coupled to the wheel and to the master pistons to cause the master pistons to move between retracted and extended positions when the wheel is rotated.

Abstract: A turbocharger-gas turbine for an internal combustion engine operable in multiple modes in a manner reducing heat losses. The turbocharger-gas turbine includes a compressor for delivering compressed air to the internal combustion engine. The compressor has a compressor housing defining an air flow path leading from an air inlet to an air outlet at opposite ends thereof. The air outlet of the compressor is in communication with an air inlet of the internal combustion engine to deliver compressed air thereto. The turbocharger-gas turbine also includes a turbine for driving the compressor to compress air for delivery to the internal combustion engine. The turbine has a turbine housing defining a gas flow path leading from a gas inlet to a gas outlet at opposite ends thereof. The gas inlet of the turbine is in communication with the gas outlet of the internal combustion engine for receiving gas therefrom.

Abstract: A thermal energy peaking/intermediate power plant is disclosed having an atmospheric Fluidized Bed Combustor (FBC) for heating compressed air which is input to a turbine. Low-grade fuels such as coal may be combusted in the FBC, eliminating the need for additional combustors requiring premium fuels.

Abstract: The present invention is an improvement to a two distillation column, cryogenic air separation process which produces nitrogen-rich and oxygen-rich products. The improvement to the process is condensing at least a portion of the nitrogen overhead from the high pressure column in a reboiler/condenser against a crude liquid oxygen stream and in an intermediate reboiler/condenser located in the low pressure column against internal low pressure column streams. The condensed nitrogen overhead is fed either to the low pressure or high pressure columns as reflux. The vaporized portion of the crude liquid oxygen stream is work expanded to provide some or all of the refrigeration required for the process.

Abstract: A refrigerated transportation container having associated therewith a cryogenic refrigeration unit and a recirculation refrigeration unit is provided. The cryogenic unit allows an initial rapid cooling of the container's interior and the recirculation unit allows the efficient maintenance of the temperature of the container's interior during transport. The container is particularly useful in a method of distributing refrigerated products to a plurality of geographically spaced distribution locations. The rapid cool down of the container's interior allows a quick return of the interior to a predetermined transport temperature which, in turn, allows minimization of the risks of a failure to maintain the products at said predetermined transport temperature.

Abstract: In an air conditioning system having the outdoor coil disposed in a wall opening with the outdoor air being required to flow horizontally inwardly pass through the coil and then flow horizontally outwardly as it is discharged, the propeller fan is placed in a horizontal plane at the top end of the coil such that the air is caused to flow into an upper plenum where the air is turned 90 degrees to be discharged. The height of the plenum is preferably chosen to optimize the performance while minimizing the plenum height.

Abstract: An apparatus for cooling fish on board a ship is provided. This apparatus includes an ice-making machine for producing fine particles of ice in a brine solution. Coupled to this ice-making machine are means for directing ice from the machine to either a vessel containing brine solution or to a catch of fish. A method of cooling fish comprising producing a slurry of fine particles in brine solution in an ice-making zone and directing the fine ice particles onto either a catch of fish or into a vessel containing brine solution is also provided.

Abstract: The present invention utilizes the combination of a vehicle having a passenger compartment, a heating and cooling air-conditioning system, and an air vent opening for providing conditioned air to the passenger compartment. Within the storage compartment of the vehicle, a food container is placed which has an air conduit connected thereto. The air conduit is also connected to the air vent opening on the dash of the vehicle so that conditioned air is directed to the internal food compartment of the food container. A fan may be provided within the conduit for facilitating the movement of air from the air-conditioning vent of the vehicle into the food compartment of the container. A modified form of the invention utilizes collapsible container walls and collapsible shelves within the container.

Abstract: A method and system for conditioning the cargo containing space of a vehicle are disclosed wherein refrigerated or heated air is introduced into a supply duct and circulated through the cargo to a return duct. The return duct or ducts are preferably formed by movable reefer pallets or racks, controlled openings in the pallets regulating flow into the return duct to develop a uniform pressure differential between the cargo space and the return duct and achieve more uniform cooling. Heat barrier spacers are arranged on vertical walls to minimize heat passage to the cargo. A method and system are also disclosed for supplying refrigerated gas through a supply duct and returning it through a return duct, a control unit being normally responsive to a master temperature sensor arranged in an inlet, a sub-master temperature sensor being arranged for sensing freezing or chilling conditions and overriding the master temperature sensor.

Abstract: Disclosed is an operation control system for a refrigerator which can prevent extreme change of the internal temperature by an extra method when abnormality occurs in its cooling state. This system judges whether the temperature change is abnormal or not, stops an operation control method based on temperature when the change is abnormal, and controls the operation of the refrigerator by another operation control method based on time in which the stop and the restart are repeated at predetermined intervals respectively.

Abstract: A retractable temperature control for refrigeration units includes a control panel pivoted for movement between an extended, accessible position and a retracted position in which it is enclosed within one of the insulated walls of the unit. Mounted on the panel are two operators, one of which controls the temperature of a thermostat and the other of which controls the position of a damper. Adjustment of the operator associated with the thermostat controls the temperature of one compartment in the refrigeration unit and adjustment of the other operator controls the position of a damper, and in turn controls the differential temperature between the two compartments provided by the refrigeration unit. The thermostat and the damper control are structured so that movement of the control panel between the retracted and extended positions does not affect the adjustment thereof.

Abstract: An air conditioning apparatus includes an external heat-exchanger having upper and lower side heat-exchanger elements, arranged in a vertical direction, each having a plurality of fluid pipes, upper and lower fan devices disposed opposite to corresponding heat-exchanger elements, and a temperature sensor disposed on one end (discharge side during cooling) of the upper-most fluid pipe of the upper side heat-exchanger element for outputting a detection signal indicating the condensation temperature of the external heat-exchanger corresponding to the condensation pressure of the external heat-exchanger. The rotation speed of the upper side fan device is regulated in accordance with the detection signal from the sensor to control the condensation pressure of the upper and lower side heat-exchanger elements within a prescribed range.

Abstract: A refrigeration system for use in an automotive air conditioner comprises a compressor for compressing vapor-phase refrigerant, a condenser connected to the outlet of the compressor, an expansion valve connected to the outlet of the valve, and a vapor pressure-adjusting valve mounted in the passage extending from the evaporator to the compressor. When the vapor pressure inside this passage is less than a certain value, the adjusting valve reduces the flow of refrigerant from the evaporator to the compressor to maintain the vapor pressure constant. A part of the liquid-phase refrigerant on the downstream side of the condenser is added to the refrigerant evaporated by the evaporator, by means of the adjusting valve.

Abstract: An improved system for reducing the work required by a gas compressor in compressing a gas, comprising a gas compressor, a post-compression heat exchanger operably coupled to said gas compressor downstream therefrom to recover heat energy from a compressed amount of gas, and a means for reducing the work required by said gas compressor to compress a pre-compression amount of gas utilizing said recovered heat energy to provide cooling for the pre-compression amount of gas wherein such means includes an absorption chiller using the heat energy of compression to providing cooling for the gas to be compressed prior to compression.

Abstract: Structure for and method of cooling or heating a space which is exposed to a natural heat influence. The structure includes a first fluid store buried in the ground so as to be at the temperature of the surrounding earth, a heat exchanger positioned in a space to be cooled and means for passing a fluid between the first fluid store and heat exchanger in a closed circuit. The structure of the invention may also include heat units for the space and hot water heaters connected in the closed circuit between the heat exchanger and first fluid store and a heat pump connected between the heat units and water heaters and the closed circuit. In a further embodiment of the invention, a second fluid store is provided in conjunction with the heat exchange structure which may also be buried so that waste heat may be utilized to heat the fluid in the second fluid store.

Abstract: A system and apparatus for compressing gaseous fluids, especially refrigerant gas vapors operating in refrigeration cycles, combining reciprocating pistons in a rotating cylinder member which is mounted for rotation in a stationary frame and is driven by an external source of rotative power. The cylinder block rotates in an encircling port ring member which contains inlet, interstage, and outlet port sets with the number of port sets, numbering more or less than the number of cylinders, to provide a vernier effect in the timing of connections between the port sets and the cylinders.

Abstract: A rotary vane gas compressor e.g. for use in refrigeration is driven by an electric motor which is cooled by a refrigerant liquid passed through a heat exchanger which is attached to the external surface of the stator of the motor. The refrigerant is then passed back into the compression chamber of the gas compressor via a port intermediate between the inlet and outlet ports.

Abstract: A non-restrictive, constant pressure refrigerant recycling and cooling unit that interrupts the normal refrigerant cycle to permit a lower temperature liquid to enter the expansion device, and thus provide a lower temperature, and therefore a lower pressure gas for delivery to the inlet side of the compressor, which acts to reduce the energy requirement and cost to operate the compressor. This reduction in pressure and temperature also results in lower operating costs and lower maintenance costs and utilizes less refrigerant quantity requirements.

Abstract: A method and apparatus for cooling a warm feed stream of aqueous liquid to close to but above the freezing point of the aqueous liquid and delivering it to a mixing tank; withdrawing an aqueous ice slurry from an ice slurry receiver-crystallizer and delivering it to the mixing tank to further cool the contents and produce temperature control of the mixing tank contents; withdrawing an aqueous slurry from the mixing tank and delivering it to a slurry thickener tank for precipitate separation thereof; removing the precipitate from the slurry thickener tank and disposing of it; withdrawing aqueous liquid from the thickener tank and delivering it to the ice slurry receiver-crystallizer; and withdrawing an aqueous ice slurry from the ice slurry receiver-crystallizer, feeding it through a freeze exchanger to produce additional aqueous ice slurry and withdrawing the aqueous ice slurry from the freeze exchanger and feeding it to the ice slurry receiver-crystallizer.

Abstract: A gem setting elegantly mounts a gem in a diadem so the gem appears to be suspended above a base by a plurality of complementary gemstones. The setting permits light to pass inwardly through the complementary gemstones and into a pavilion of the gem to enhance the appearance of the gem.

Abstract: The invention relates to a gem compound comprising a plurality of gems bearing a melt adhesive layer, wherein the gems bear on their setting side a first melt adhesive layer, therebelow a filling layer which fills the spaces between the individual gems, and therebelow a second melt adhesive layer which is substantially flat and welded to the first melt adhesive layer in the area of the tips of the gems.

Abstract: A washing apparatus comprises a pedestal, drive device fitted to the pedestal, a tub body provided with a washing tank, two elongate fitting legs fitted to the tub body at one end and attached to the pedestal at the other end, thereby supporting the tub body above the pedestal at a prescribed distance, and an outer casing which is detachably fitted to the fitting legs to enclose the drive device and tub body.

Abstract: The invention relates to an apparatus or device for the treatment of a material, in particular a web of material or pulp, made to pass between at least two endless permeable belts, for instance screen belts or the like conveying means, preferably for the displacement washing of a filter cake or for washing fibrous matter, the material being passed between the belts along at least two containers serving for the supply of a treatment medium, for instance a washing fluid, a bleaching agent or other chemicals. It is the object of the invention to provide a compact apparatus of this type at simultaneous good effectiveness.

Abstract: The venturi device is removably mounted within and concentrically of a venturi housing of the apparatus. It has a plurality of elongate fluid passageways located between the inner and outer cylindrical surfaces thereof, and extending substantially parallel to a central axis of the device and housing. The passageways are spaced from each other about the circumference of the venturi device, have fluid inlets their adjacent closed ends, and have open ends adjacent an outlet section of the device possessing a frusto-conical surface that extends at a preselected angle relative to the central axis and that directs streams of fluid discharged from the open ends of the passageways angularly toward the central axis.

Abstract: An anti-theft device for motor vehicles of the kind having a gearshift lever and a handbrake lever mounted on the floor in line with each other, consists of a tubular member open at its bottom which is to be fitted over the handbrake lever, and a bi-furcated member which is to be pressed onto the gearshift lever. The bi-furcated member includes two bars which are slidingly fastened in two bores at the ends of an axle which is rotatably mounted in the upper end of the tubular member and which can be locked in any position by a tooth pushed upwards by a lock in the tubular member by entering a space between two teeth of a gear on the axle. The two bars are recessed by grooves in their sides facing each other which can be engaged by two coaxial pins in the axle, which are pressed into a pair of grooves by the same lock and can be pushed inwardly of the axle after unlocking.

Abstract: A compound of the formula (I) ##STR1## where A is an alkylene or alkenylene group, R.sub.1 is an aryl group which may be substituted, R.sub.2 is a hydrogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, a halogenated lower alkyl group, a cycloalkyl group, a lower alkoxyalkyl group, a lower alkylthioalkyl group, a phenyl group which may be substituted or an aralkyl group which may be substituted, R.sub.3 is a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group or a halogenated lower alkyl group, or R.sub.2 and R.sub.3 may be combined to form a group of --(CH.sub.2).sub.n --(n is 3 or 4), or salt thereof, which is useful as a herbicide.

Abstract: A door lock assembly comprises an outside operating section, an inside operating section and a mechanical lock, detachably mounted on a door. The outside operating section includes a switch button array which operates an electromagnetic plunger into an unlocking mode when a preselected number is set into switch buttons of the array. Operation of the electromagnetic plunger moves a mechanical on-off assembly to an off-position so that a rotatable knob can be manually rotated to operate a slidable dead bolt of the mechanical lock. The on-off assembly includes a resiliently biased slidable stop member mounted in a rotatably mounted member and having a reduced shoulder portion engageable in an opening in a cylindrical portion of a stationary hollow member, with the stop member being movable to an off-position disengaged from the opening by actuation of the electromagnetic plunger.

Abstract: A key assembly which is composed of a flat key and a credit card-like key holder members. This assembly does not make the pocket bulky and can conveniently be used as a spare key for a car door lock, a building door lock, etc.

Abstract: A roll forging machine includes an automatic stock feed which receives the stock in a receptacle from a conveyor and then swings the stock to a horizontal feed position after sensing the temperature of the stock. If the stock temperature is insufficient for proper forging the receptacle swings to a dump position to return the stock to a furnace. If the stock temperature is sufficient the receptacle in the horizontal position is indexed into the forging rolls and to place the stock into a stock gripper of a transfer. The stock gripper is mounted on a grip slide for movement in the "X" direction aligned with the direction of the roll passes. The grip slide is in turn mounted on a carriage for movement in the "Y" direction transverse the direction of the roll passes. Both the grip slide and the carriage are driven electrically by respective servomotors in turn driving timing belts to which the carriage and grip slide are clamped.

Abstract: Plastic working method and apparatus are disclosed. The plastic work such as forging is carried out by partial pressing contact of a die with a partial portion of a workpiece. The die is moved in a swinging or circular rocking fashion. The plastic working apparatus comprises a lower die for supporting the workpiece; an upper die swingably provided in a swinging plane about a predetermined position for relatively depressing the workpiece with respect to the lower die in accordance with the swing motion and for performing the plastic work to the workpiece in cooperation with the lower die; and a moving mechanism for relatively moving the workpiece and the upper die within the swing plane during the working operation.

Abstract: A press brake with a displacement sensor of an electric signal output has a base distance portion; a displacement sensor disposed opposite the base distance portion and having an electric signal output; a pair of dies one of the molds being provided with either the base distance portion or the displacement sensor, the other being provided with the remaining one of the base distance portion or the displacement sensor through a linear actuator; a servo amplifier for inputting an electric signal output coming from the displacement sensor; a servo valve controlled by an output signal coming from the servo amplifier; and a cylinder controlled by the servo valve and adapted to actuate either one of the pair of dies.

Abstract: The method of making copper rod by rolling is significantly improved by effectively controlling the water-soluble oil emulsion used to lubricate the rolls by employing a conductivity probe to maintain the conductivity of the emulsion within desired operating limits.

Abstract: A method of superplastically forming a part from a blank of material. The blank is placed between opposed die structures and heated to a superplastic forming temperature. Positive fluid pressure is supplied at an increasing rate against a front surface of a blank to stretch the same into a cavity of one of the dies to begin formation of the part. A positive fluid pressure is also applied against the back surface of the blank, and acoustical energy emitted by the material of blank resulting from the occurrence of cavitation in the material is sensed. The sensing of acoustical energy is employed to control one or more of the above parameters until the formation of the cavities substantially reduces or ceases altogether.

Abstract: A method of manufacturing vehicle wheels from a disc blank, in which the wheel has rim portions of uniform thickness and different lengths. The wheel is made by spin forging the edge portion of the disc to form an angled portion, splitting the disc into two split portions one of which has the angled portion joined at its end and forming the split portions into a desired rim configuration. A groove may be formed on the periphery of the angled portion to precisely fix the location of the split.

Abstract: On a turret (30) which can be driven in rotation about a central axis (A), a plurality of expanding mandrels (42) are arranged all around the central axis (A). They are each essentially composed of a supporting member (44) which is secured to the turret (30) and defines an expanding-mandrel axis (B), a plurality of segmental bars (52) which are arranged all round the expanding-mandrel axis (B) and are guided on the supporting member (44) for radial adjustment, and a wedge (70) which is displaceable along the expanding-mandrel axis (B) to spread the segmental bars (52) apart. The wedges (70) are displaceable in succession, by a common actuating member, during one revolution of the turret (30). The actuating member is a central cam member (18) on which each of the wedges (70) is supported at least during a portion of each revolution of the turret (30) corresponding to the distance between two adjacent expanding mandrels (52).

Abstract: Elongated straight cylindrical metal rods are threaded along opposite end portions, and the cylindrical outer surface of the center portion of each rod is marked to form a visual indicator of the longitudinal center of the rod. The straight rods are successively inserted into a rod bending machine having a mandrel with a mark indicating the center plane of the bending operation. The mid-point mark on each rod is aligned with the center plane mark on the machine, and the rod is bent to form a precision U-bolt. Preferably, the mark identifying the center of each rod extends circumferentially around the metal rod and is formed by a stripe of color contrasting ink directly on the rod or on a label attached to the rod to provide a permanent mark which does not require rotating the rod to find the mark.

Abstract: This invention provides a continuous hot rolling process for making thin strip in which it is possible to roll strips at high rolling speeds required to keep a finisher delivery temperature equal to or higher than an Ar.sub.3 transformation temperature. The gist of the present invention resides in a continuous hot rolling process in which the rolling speed of a final finishing mill is kept constant or slightly increased until the leading end of rolled strip travels from the final finishing mill to a down coiler which process comprises: rolling a predetermined length of the leading end portion of a stock being rolled in accordance with a strip thickness greater than a finished thickness; then reducing the strip thickness to the finished thickness by gauge alteration in rolling; and subsequently rolling the following portion.

Abstract: The present invention is drawn to a method of manufacturing a tripod element of a homokinetic joint, and more particularly, to a method of forming grooves in the trunnions of a blank from which the tripod element is manufactured. The grooves are formed by punches which have forming edges profiled in correspondence with the grooves to be formed. The blank is positioned such that the punches occupy respective spaces each defined between two adjacent ones of the trunnions and such that the forming edges confront the trunnions, respectively. At least one of the punches is moved in a direction toward the central axis of the blank until the respective ones of the forming edges of the punches contact the trunnions to cause the blank to be self-positioned in contact with the forming edges.

Abstract: A rivet-setting tool for pull-to-set blind rivets having mandrel-gripping jaws in which the teeth are widely-spaced at a level of only 8-15 teeth per inch; preferably the teeth in each jaw have non-uniform spacing, the spacing between some pairs of teeth being at least twice the spacing of the pairs of teeth in the same jaw; preferably, also, each tooth in one jaw is located directly opposite a tooth in the other jaw.

Abstract: Devices and processes for inducing fiber transfer in order to evaluate and analyze wear properties of materials. A second pad which carries a specimen of material or abradant orbits or reciprocates with respect to a first such pad. A drive means and control means allows the movement of the second pad to be precisely controlled, so that its period of orbit or reciprocation can be minutes long if desired, and can be stopped after a predetermined time or number of cycles, after one cycle, or at any fraction of a cycle or any desired point on the first pad. The device thus allows highly controllable conditions for inducing fiber transfer, so that highly accurate measurements of fiber transfer may be made and wear and durability properties of materials analyzed.

Abstract: In a method for checking and monitoring the friction between the traction sheave and the suspension ropes of an elevator, the slippage between the traction sheave and the suspension ropes of the elevator is measured, the elevator comprising an elevator machine, a hoistway and an elevator car and a counterweight moving in the hoistway. The rope slippage is measured either periodically by performing test drives or continuously by means of an impulse device placed in the elevator machine and measuring the motion of the tractin sheave, an impulse device monitoring the movement of the elevator car and an impulse device monitoring the load in the car. The data provided by these impulse devices is transmitted to a computer which calculates and monitors the relative slippage between the traction sheave and the suspension ropes of the elevator.

Abstract: The present invention relates to a pressure detecting apparatus which detects the peak of combustion pressure in a cylinder of an internal combustion engine and the timing of that peak. The apparatus according to the present invention can be constructed in two alternative ways. That is, in one way, once stored data of combustion pressure in the cylinder is read out in reverse order, thus the difference between the read-out data and the data of combustion pressure in the cylinder is obtained, and the peak of combustion pressure in the cylinder and the timing of the peak are detected in accordance with the difference. In another way, the inflection points of the differentiated result of the data of combustion pressure in the cylinder are detected, and the peak of combustion pressure and the timing of the peak are detected in accordance with the inflection points.

Abstract: An apparatus for inspecting a tire for structural defects as the tire is rotated on a stand comprises a movable transducer transmitter for directing a plurality of successive collimated bursts of ultrasonic energy against the tire surface, said bursts passing through the tire and forming inspection areas having the same diameter and overlapping each other as the tire is rotated during an inspection cycle. A movable receiver transducer located on the other side of the tire from the transmitter is constantly positioned to receive the collimated ultrasonic energy that passes through each inspection area. Coordination control elements are provided for moving the transmitter transducer and the receiver transducer from one side of the tire to the other generally parallel to its axis of rotation while successive ultrasonic bursts are directed through the tire as it rotates during each inspection test and while maintaining substantially the same distance between the transducers for each burst.

Abstract: The apparatus of the present invention relates to a down hole tool capable of extraction of valid samples and making pressure measurements useful in calculating formation permeability. The tool incorporates the features of a straddle packer to allow formation fluid specimens to be taken at large flow rates without depressing the pressure below the formation fluid bubble point. When used in combination with a pressure probe the tool is used to obtain meaningful permeability readings in a larger radius area than previously permitted with known designs. Additionally, the apparatus of the present invention allows flow control during the creation of the pressure pulse which enhances extraction of valid samples and the permeability determination.

Abstract: A running blade is adapted to move at the same speed as a continuously running sheet and to generate a burst perforation through the sheet. The force exerted by the blade against the sheet is measured and used to calibrate a non-destructive sheet strength sensor.

Abstract: A method and device for determining the strength of a sheet material, such as paper, utilizing floc size and the variability of the local basis weight of the sheet. The force required to deflect the moving sheet out of a nominal position, the distance the sheet is deflected by said force and the average tension applied to the sheet may also be utilized in the above determination of sheet strength.

Abstract: A vertical speed indicator uses a substantially rigid hollow closed air chamber; a capillary tube having a reduced inside diameter connected to the chamber for routing atmospheric air from an aircraft static system at a reduced flow rate into the chamber; a differential pressure transducer having two inlet ports; a pneumatic conduit connecting the chamber and one of the ports of the transducer for exposing that port to internal chamber air pressure; a pneumatic conduit connected to the other port for exposing that port to atmospheric pressure occurring within the static system; and electronic processing circuitry connected to the transducer for providing an indication of the vertical speed of the aircraft.

Abstract: A cavity such as a chamber (10) of a hydraulic cylinder (2) containing a movable piston (4) is equipped with transducers (12) for transmitting alternating pressure signals into a fluid in the chamber and for receiving signals from it. The fluid chamber acts as a resonant tank circuit for determining the frequency of an external electronic oscillator (24). The frequency of oscillation of the circuit indicates the depth of the cavity, i.e., the position of the piston in the cylinder. Multiple modes of oscillation are employed (34, 36) in the same chamber to provide high accuracy and resolution of ambiguities. In one embodiment chambers (10', 66) on both sides of the piston (4') of a double-acting cylinder (2') are measured, and the readings are combined (76) to reduce errors that would otherwise result from changes in temperature, pressure, viscosity and other parameters unrelated to the position of the piston.

Abstract: The directional thermal anemometer transducer includes an electrically non-conducting substrate having at least two areas substantially thermally isolated from one another covered with a resistive sensing conductor, the conductor extending only within the region of connected flow over the transducer. The resistive sensing conductors can be of metal film or resistive material which exhibits a change in its electrical resistance as a function of temperature. Barrier plates mounted at each end and perpendicular to the longitudinal axis of the transducer interferes with flow parallel to the transducer in order to create wake turbulence behind the plates.