Abstract: Substantially fluoride-free phosphoric acid is produced by the acidulation of phosphate rock with sulfuric acid wherein the acidulation reaction is conducted in the presence of added potassium as K.sub.2 O bearing compounds, e.g. KHSO.sub.4, K.sub.2 SO.sub.4, KH.sub.2 PO.sub.4 or KOH, and additional silica, to precipitate fluorides and silica as potassium silicofluoride and then removed on separation of the gypsum formed. Optionally, additional silica may be added to the phosphoric acid solution recovered after precipitation and removal of the gypsum, to precipitate additional fluoride as potassium silicofluoride to further purify the phosphoric acid. In a further embodiment sufficient potassium may be added along with additional silica in the acidulation step to produce potassium dihydrogen phosphate and phosphoric acid as additional products.

Abstract: A full bridge inverter includes four bipolar transistors of like conductivity type, connected in a bridge circuit including an apex to which a load is connected. During a first time interval, emitter collector paths of a first pair of transistors are connected betwen a DC source and the apex so that current flows in a first direction through the apex while the transistors are forward biased. The emitter collector paths of a second pair of transistors are connected with the source and the apex so that current flows in a second direction through the apex during a second interval while the transistors of the second pair are forward biased. A first transformer has first and second windings respectively connected in series with the emitters of the transistors of the first pair, such that voltages at the emitters of the transistors of the first pair have a tendency to vary in the same direction.

Abstract: A drawing instrument comprises a pair of limbs pivoted together at their inner ends to form an assembly. A bow top has an interior hole and fork limbs embracing the assembly of the inner ends of the pivoted limbs. The fork limbs include pivot holes for receiving the pivot which connects the pivoted limbs to the bow top. A centralizing member is held between and is keyed to the inner ends of the pivoted limbs. A portion of the centralizing member projects upwardly into the interior hole of the bow top. The centralizing member includes an elongated pivot receiving hole. The centralizing member is effective to press against a side wall of the hole in the bow top to cause the bow top to turn and keep central upon any angular movement of one of the pivoted limbs with respect to the other pivoted limb.

Abstract: A boring tool assembly performs both the rough and finish cutting operations upon a metal work piece without power activation or manual adjustments of the tool units between the cutting strokes. The assembly includes a boring bar having a pair of fixed, diametrically opposed rough cut tool units, and a pair of retractable finish tool units diametrically opposed to each other also. The tool units are automatically operative in response to either the rough cut or the finish cut of the boring tool assembly. Spring biased plungers normally pivot the finish cutting units toward their cutting positions. During the initial or rough cutting operation, forces act upon the heel of the finish tools causing retraction from the cutting position. This is possible due to the cutting edge configuration and angle of orientation of the tools, the positioning of the tools on the trailing side of the boring bar centerline, and the direction of advancement of the boring bar.

Abstract: The provision of an air-fuel ratio control is made to the secondary side of a twin-barrel carburetor as well as the primary side thereof.

Abstract: In an automatic telephone information retrieval system, each subscriber entry is encoded according to primary name, secondary name, primary address, secondary address, generic occupation and specific occupation. The entire contents of a local telephone directory may be electronically stored at memory addresses based upon the above encoding. Statistical methods are used to ensure a workable distribution of subscriber entries over the available memory addresses. The information is retrieved from memory by successively dividing the memory into "divided down" portions. Division points, which are boundaries between neighboring divisions, are designated in a form directly convertible into address coordinates of a random access core storage to speed information retrieval. Electronic calculating and comparing circuits automatically search the memory as a function of the division points, and also provide rapid and automatic address range computations.

Abstract: A shearing device for cutting rod of the type comprising a pair of coplanar discs with projecting blades has the blades mounted in grooves in the discs so that the tips of the blades can be moved into and out of the path of the rod, thereby enabling the discs to rotate continuously and thus avoiding the problem with the known shearing device of accelerating and stopping the discs and ensuring that the blades are moving at precisely the same speed as the rod during the cutting action.

Abstract: For securing together a pair of skis and ski sticks a pair of holder members are secured one on the upper face of each ski, and a pivoted securing arm on each holder member can be moved into a position in which it is locked to the holder member of the other ski, thereby retaining the skis and the ski sticks irremovably together. The holder members may be secured to the skis by screws which have a protective cover to prevent access. The locks may have a pivotable protective snow cover. Preferably at least some of the components are coated with a water-repellant plastics material.

Abstract: A self-advancing, hydraulically powered, mine roof support comprises at least one advancing piston and cylinder unit located in or adjacent a base means of the support and attached at or towards the front of the roof support to a lifting ram operable along an axis normal to the general plane of the base means.

Abstract: A portable gamma radiation dose rate meter suitable for use over 3 or 4 decades over the dose rate range 0.1 mR/hr and 1000 R/hr which incorporates an ion chamber or other radiation detector and a null deflection readout system using a calibrated potentiometer and two single light emitting diodes as high and low indicators.

Abstract: A rotary piston internal combustion engine of the epitrochoidal type is provided with means whereby the cooling effect of a cooling liquid medium on a trailing chamber portion of the combustion chamber is reduced or eliminated. Thus a tendency that the mixture portion within the trailing chamber portion is discharged unburned with the exhaust is eliminated, thus improving the fuel economy and HC control in the exhaust.

Abstract: An ultrasonic probe particularly suitable for ultrasonic diagnostic equipments of the electronic scanning type is made up of a multiplicity of piezoelectric transducer elements, each in the shape of a rectangular plate with electrode films coated on both sides, arranged in a row at intervals and an acoustic impedance matching layer placed on the row of the transducer elements. The width-to-thickness ratio of each piezoelectric plate takes a value not greater than 0.8 and preferably between 0.4 and 0.7 so that the plate can vibrate in width expansion mode. It is highly preferable that the impedance matching layer has a laminated structure given by two layers which are different in acoustic impedance of the respective materials and individually have definite thicknesses.

Abstract: A closed-loop mixture control system for an internal combustion engine of a roadway vehicle includes a vehicle start sensor and a voltage sensor to determine whether the fuel quantity at the instant the vehicle is started from at rest is below a predetermined value. When the signals from both sensors occur simultaneously the control voltages instantly varied to increase the fuel quantity.

Abstract: Temperatures are automatically measured with a Wheatstone bridge including first and second branches and a diagonal connected between taps of the branches. The first branch includes first and second series connected resistors respectively having values of P and Q; the second branch includes third and fourth series connected resistors respectively having values of R and A. A voltage source, having a value E, is connected to energize the branches in parallel. The third resistor is temperature responsive and has a positive temperature coefficient so that the value of R is given by:R = R.sub.0 (1 + .alpha..sub.0 T)whereinR.sub.0 = the resistance value of the third resistor at 0.degree. C,.alpha..sub.0 = the temperature coefficient of the third resistor, andT = temperature in degrees Centigrade.

Abstract: Radiant energy is converted into electric energy by irradiating a capacitor including an ionic dielectric having a dipole layer only on or near its surface. The dielectric is selected from the group consisting of the rare earth trifluorides and trichlorides, and is preferably lanthanum trifluoride or lanthanum trichloride. The radiant energy cyclically heats and cools the dielectric to cause cyclic changes in the capacitance and resistance of the capacitor without changing the dielectric state. The capacitor is initially charged to a voltage just below the dielectric breakdown voltage by temporarily connecting it across a source of emf causing a current to flow through a charging resistor to the dielectric. The device can be utilized as a radiant energy detector, as well as a solar energy cell. In the latter case, the dielectric is heated and cooled at a predetermined frequency and the capacitor is connected in circuit with a means for resonating the capacitor at the frequency.

Abstract: A mine roof support comprises a plurality of hydraulically extensible chock legs attached at their upper ends to one or more elongate roof bars by means of a projection on each chock leg passing through an aperture in the underside of the roof bar(s) to be located in articulated manner in any one of a plurality of positions along the roof bar(s) and within the roof bar(s) by abutment means.

Abstract: In a method and equipment for refurbishing gas turbine blades a portion of each blade extending from the tip is rolled under pressure, the direction of rolling being towards the tip, to effect extension of the tip, after which the extended tip is machined to a predetermined overall length of the blade, the rolling being effected between a pair of rollers, one with a convex profile and the other with a concave profile corresponding to the inside and outside respectively of the aerofoil section of the blade, one roller being fixed and the other roller being movable by pressure applying means towards the fixed roller, a carrier for the blade being rotatable and slidable in a guide aligned with the position of closest approach of the rollers, and driving means being provided for rotating the fixed roller such that its periphery moves through the position of closest approach in a direction towards the guide for the carrier.

Abstract: The invention concerns the production of closed containers filled with a liquid or particulate material. Production takes place on a machine having two tiers revolving about a common, stationary shaft. The container wall is shaped from a blank and then welded and the container bottom fitted in the upper tier. The container is filled shortly before or during its transfer to the lower tier where the lid is fitted and the finished product swung out onto a conveyor belt.

Abstract: A device feeds thread into a winding and traversing mechanism of a winding machine. The thread is fed to a spool via a traversing device having a thread guide and a reverse thread roller. The start of the thread is fed to an entrainment means via a slot that is open at one end in the winding machine. The device is a combination which comprises a traversing device housing rotatably mounted on the winding machine and a mechanism for effecting rotatable adjustment of the housing about a longitudinal axis.

Abstract: In a line pulling apparatus comprising a capstan and a pulley that rotate in unison on the stationary sleeve of a conventional capstan drive unit, line is wrapped around both the capstan and pulley for positive gripping of the line. A stationary plate member disposed between the capstan and pulley, contains a set of gears that extend above and below the plate member for stable, three-point engagement with teeth formed in the capstan and pulley. A line guide mechanism including a cut-out section on the plate member guides line from the capstan to the pulley. An upstanding member formed on the plate member holds the line in the pulley during rotation.