Abstract: Method of producing a mold from a ceramic composition which can be washed-out with water after use thereof in a molding process, the method including forming a ceramic composition by mixing from about 30 to about 80 weight percent of at least one hemihydrate including alpha-calcium sulfate hemihydrate or beta-calcium sulfate hemihydrate, from about 5 to about 45 weight percent of fire clay, and from about 5 to about 25 weight percent of at least one silicate-based filler. About 100 parts by weight of the ceramic composition are mixed under stirring into from about 46 to about 54 parts by weight of water to form a slurry. The slurry is poured into a formation mold suitable for forming the desired mold and the slurry contained in the formation mold is allowed to set and form a set body. The set body is then removed from the formation mold and dried to provide the mold.

Abstract: An aqueous silicic acid sol which is freeze-stabilized and which is useful for the production of phosphate-based embedding compositions used in dental technology, the aqueous silicic acid sol including from 25 to 50 weight percent of silicon dioxide; and from 2 to 10 weight % of a compound which is one of urea or a urea derivative and which has the general formula: ##STR1## wherein X and Y are groups selected from the group consisting of an --NH.sub.2 group and an --NHR group, in which R is an alkyl radical having from 1 to 4 carbon atoms.

Abstract: An active switch for the intersection region of tracks for mechanically transversely or laterally guided vehicles having support wheels without flanges; the switch which is adapted to be forced open by the vehicle and includes only a single adjustable switch member in the form of a switch tongue pivotal about a fixed bearing in the switch frog, is bent into its end position by the vehicle itself by being pressed against abutments; the cross section of the switch tongue has an approximately constant bending stiffness over its length whereby the switch tongue in the unstressed condition preferably has a curvature that lies between the curvatures of the one and the other end position.

Abstract: A vehicle system for local public passenger transportation, in which a number of vehicle components are used to realize a vehicle system according to a building-block system. The vehicle components are so constructed that they can be assembled into vehicles or trains usable only with tracks, selectively with or without tracks, or only without tracks.

Abstract: A process for intermittent control of a cyclically operating internal combustion engine wherein, in the succession of working cycles, working strokes are skipped--in approximately uniform distribution--and the number of skips is varied in dependence on the load. Fuel is fed in a controlled fashion only to the nonskipping working chambers of the internal combustion engine independently of the load in a constant quantity optimal for consumption. For a sensitive power distribution, especially in the low load range, the number of skips is varied chronologically at least approximately randomly and independently of the speed, i.e., the temporal density of the working strokes is varied. This can be accomplished by setting differently finely staggered firing patterns or by a stochastic ignition setting.

Abstract: A steerable vehicle adapted to be driven on roads, especially for the public local passenger traffic, which has a steerable axle with deflectable wheels and at least one axle with wheels immovable relative to the axle which is pivotally secured at the vehicle in a bogey-like manner, and with cross-guide rollers mounted on both sides of the vehicle within the area of the vehicle axles and carried at least indirectly by the respective axle bodies. The pivotal axle is elastically centered in a straight driving position, out of which it is pivotal by the steering forces produced by the cross-guide rollers against the force of centering springs, whereby the centering springs and the prestress are chosen so strong that brake force differences of one vehicle side compared to the other side do not effect an automatic axle deflection.

Abstract: A traffic system for track-guided vehicles with steerable wheels, in which a guide groove, guide web or the like, which determines the track and is adapted to be mechanically detected by the vehicles, is provided on the side of the road and a guide lever detecting the guide groove course is provided on the side of the vehicle, whereby the movements of the guide lever are adapted to be transmitted indirectly to the steerable wheels by interconnection of a force and movement transmission mechanism supplied with auxiliary energy; the guide lever which is pivotally connected at the axle member of the vehicle having the steerable wheels is deflectable within a small angular space that corresponds only to a fraction of the maximum deflection angle of the steerable wheels while additionally all parts that participate in the force flow of the movement transmission of the guide lever between the guide groove, on the one hand, and the axle member, on the other, are constructed so strong that the vehicle can be form-loc

Abstract: A traffic system in which the cross-guide device in the operating position thereof is arranged immovably in the transverse direction relative to the axle body of the vehicle axle having steerable wheels and is constructed so sturdily itself as also as regards its suspension that the vehicle can be form-lockingly track-guided and/or laterally displaced also without deflection of the steerable wheels by way of the cross-guide device without damage and in an operationally reliable manner; force-measuring devices for determining the lateral forces exerted on the cross-guide device are arranged in the suspension of the cross-guide device while the force- and movement-transmitters are so constructed that the steerable wheels are automatically deflected always so as to maintain a predetermined desired value of the lateral force at the cross-guide device.

Abstract: A drive aggregate for electric vehicles, especially for trackless street vehicles, which is equipped with an electric shunt motor provided with field current control and with a change-speed transmission having at least two forward speeds connected behind the electric shunt motor; the electric shunt-wound motor thereby has a relatively high rated rotational speed in relation to its maximum rotational speed and a relatively reduced field-weakening range whereby the change-speed transmission is an automatic transmission connected with the electric shunt motor by way of a speed-reducing gear while the oil pump of the automatic transmission is driven by an electric motor coordinated thereto which operates at substantially constant rotational speed.

Abstract: A drive arrangement for motor vehicles equipped with a mechanism for raising the idling rotational speed of the driving engine during its warm-up phase and with an automatic transmission whose lowest speed is adapted to be engaged by at least one servo-device; the servo-device is thereby adapted to be automatically disengaged upon actuation of the vehicle brake in the lowest speed which is coordinated to the selected drive range.

Abstract: A control installation for shifting back an automatically shifted planetary gear change-speed transmission in which the various speeds are adapted to be engaged by servo-devices that are actuated by a pressure medium whereby the servo-device of the speed to be engaged is brought into readiness and is fully engaged only after the determination of the correct shifting point by means of at least one feeler device as a function of the latter; a solenoid valve is coordinated to the pressure line leading to the actuating member of the servo device and is adapted to be shifted by means of a shifting pulse into a position releasing the pressure to the actuating member of the servo-device whereby the shifting pulse is triggered by at least one rotational speed transmitter which detects the rotational speed condition of a corresponding transmission member.

Abstract: In the manufacture of phosphoric acid by treatment of phosphate ores with excess phosphoric acid and precipitation of calcium ions as calcium sulfate, the purity and quality of the byproduct calcium sulfate is substantially improved by subjecting the monocalcium phosphate extract of the ore before precipitation of calcium sulfate to one or more preliminary treatments, whereby contaminent ions are substantially and preferentially removed from the extract while the calcium remains substantially in solution. These preliminary treatments may include separation of fluoride by reaction with silicon compounds, separation of radium by reaction with barium compounds in the presence of sulfate ions, and separation of strontium as strontium sulfate.