Abstract: In a process for laying underground service lines without excavation by means of a ram boring machine, old pipe lines already buried underground are replaced by new service lines without having to tear up the ground or destroy the old pipe line. To enable the new line to be laid accurately in position and to be accurately targeted the ram boring machine is provided with a guiding bore passing axially through the casing and is guided on the old line.

Abstract: In a model airplane having a landing gear 5 provided on a fuselage 1 or wing made as a zinc-alloy die-casting where a bearing member 19 is suspended from a strut 18, it is desirable that the manufacture of an accurately modelled landing gear be simplified. This is achieved in that a landing gear 8 formed with two clasp member arms 10 made of elastically bendable plastic forms the bearing member 19 and at least partially the strut 18 with a tenon 11 being inserted and glued into a cast cavity 12 in the fuselage 1/wing wherein the clasp member 8 bears against the zinc-alloy die-casting with a thickening shoulder 17. The clasp member being a plastic moulding permits a finely engraved realistic appearance of the strut and bearing member while simplifying assembly of the wheel pair and reducing the scrapping rate.

Abstract: A string instrument, particularly a base guitar or an electric guitar, includes a body which defines a compartment for receiving the components of an electric sound pickup and an amplifying system. A cover is releasably mounted on the rear side of the body of the instrument for closing the compartment. A frame is fastened to the side wall of the compartment. The cover is constructed so as to fit on or into the frame. Locking members are provided between the frame and the cover for mounting the cover on the frame and for removing the cover from the frame.

Abstract: A convoluted boot made of a thin-walled thermoplastic elastomer with at least one collar region which, on its inside, has an internal annular bead engaging a flat annular groove of a universal joint with a rectangular or trapezoidal cross-section, where at least the one collar region, on its outside, has an annular groove with a rectangular or trapezoidal cross-section for tensioning element, which annular groove is provided with a substantially flat bottom part resting against the tensioning element and is wider than the internal annular bead, and the collar region, within the flat annular groove in the region of the internal annular bead, has at least one recess-like annular gap with a rectangular or trapezoidal cross-section whose cross-sectional depth is greater than its width.

Abstract: A weighing scale with two overlapping weighing beam arrangements hinged in the middle of the weighing scale by means of connecting rods with pivot bearings and pivots and connected to a ground plate at the extremes has a pendulum foot (19) at the ends of each weighing beam arrangement which can swivel in a foot groove on the ground plate (39). The ends of the weighing beam arrangements accommodate a pivot block arrangement with two opposed pivots (50, 51). Support in pivot bearings is located beneath the weighing beam arrangement. The pivot block arrangements and the pivot bearings are located in the centre with regard to the weighing beams and transmit the support forces from the center to the weighing beams.

Abstract: A method and an apparatus for the denitrification and desulfurization of hot waste gases, particularly from furnaces. A crude gas flow is initially conducted through a denitrification plant and through the endothermic part of a heat-utilizing plant. Subsequently, the flow is conducted into a desulfurization plant. The purified gas flow discharged from the desulfurization plant is conducted through the exothermic part of the heat-utilizing plant and is subsequently transferred to ambient. By means of a cooling trap, a portion of the heat contained in the crude gas flow before the contact with the heat-utilizing plant is removed while precipitating sulfuric acid in the form of vapor, and this heat is then added to the purified gas flow before the contact thereof with the heat-utilizing plant.

Abstract: A burner apparatus which comprises a pilot burner including a nozzle and swirlers disposed around the nozzle, and a plurality of main burners which are arranged around the pilot burner and each of which comprises a nozzle and swirlers disposed around the nozzle; and the angle of the swirlers for the pilot burner is set larger than the angle of the swirlers for the main burner so that the angles of the two types of swirlers cross. NOx production can be considerably reduced with a very simple structure based on the present invention for combustion in boilers and gas turbines.

Abstract: A method for the preparation of active magnesium hydride-magnesium-hydrogen storage systems, which absorb hydrogen reversibly is disclosed. Finely divided magnesium is doped with nickel for this purpose. A pressure reactor is charged with a mixture of finely divided magnesium and an amount of nickel sufficient for the doping. Tetracarbonyl nickel is produced in the pressure reactor and subsequently decomposed. Carbon monoxide is then withdrawn from the pressure reactor and the doped magnesium obtained is hydrogenated at temperature of .gtoreq.300.degree. C. and elevated pressure.

Abstract: A method is disclosed for the preparation of flexible polyester polyurethane foam by reaction of at least difunctional polyesterols with at least difunctional organic isocyanates in the presence of catalysts and a stabilizer mixture of organic and organosilicon compounds, water, optionally blowing agents and optionally conventional additives, wherein the stabilizer mixture used comprisesa) a (meth)allyl polyoxyalkylene ether polymer or its copolymer with vinyl monomers andb) a polyoxyethylene-polysiloxane block copolymer,in a ratio by weight of a:b of 1:9 to 9:1. The polyester foam obtained are open celled to a high degree and have an excellent die-cuttability.

Abstract: A motion converter for small appliances driven by electric motors, such as electric toothbrushes, electric razors or the like, comprising a motor, tool bit and tool bit carrier, which is driven by the rotary motion of the motor and imparts a preferably orbital motion to the tool bit. The latter is accomplished by a novel mechanism for converting the rotary motion of the motor shaft into a generally transverse reciprocating motion. The mechanism employs a follower having a guide slot with parallel side faces and conically extending, radial outer contoured surfaces. The follower comprises a bore for the motor shaft or for a cam on the motor shaft and is slidingly mounted thereon.

Abstract: An enclosing sleeve for a one-way valve presses an elastomeric sheath against the valve body to provide a seal between the sheath and the valve body. In addition, the sleeve can form a closure over the outlet end of the valve body protecting it from contamination or contact with contaminating surfaces.

Abstract: A video signal processing apparatus is arranged to obtain, in reproducing a video signal including color difference line sequential signals, the concurrence of color difference signals for each of odd-number and even-number fields by using both the color differences line sequential signals of the odd-number and even-number fields which are concurrently generated. Any drop-out of a color difference signal in a horizontal scanning line in one of these two fields is compensated for with a color difference signal located close to the horizontal scanning line.

Abstract: A method of manufacturing multiple-layer molded articles with an outer skin of compact thermoplastic material and a core of foamed thermoplastic material includes initially introducing the material for the skin into a mold cavity in a quantity sufficient for the desired thickness of the skin and subsequently feeding into the mold cavity the material for the core to which the expanding agent has been added. During and/or after being introduced into the mold cavity, the core material containing expanding agent is temporarily subjected by means of an additional gas and/or a pressurized, low-boiling liquid to an active pressure which exceeds the gas pressure of the expanding agent. Subsequently, the additional gas or the low-boiling liquid is removed from the hollow space which is still free of skin material and core material.

Abstract: The torsional oscillation damper intended in particular for the driving train of a motor vehicle comprises a disc part 11 which is rotatable round an axis of rotation and a housing part 17 which is equiaxially rotatable relative to the disc part 11, at least partially surrounds the disc part 11 and, together with the disc part 11, limits at least one damper chamber which is sealed from the exterior for receiving a viscous damper fluid. A displacement member 31 arranged on the disc part 11 or on the housing part 17 in each damper chamber divides the damper chamber into two displacement compartments which are connected to one another by a throttle channel 41. The disc part 11 and the housing part 17 are resiliently coupled together by a plurality of springs 23.

Abstract: A composition is disclosed which is useful for the water-repellent impregnation of porous mineral building materials. The composition is based on organosilicon compounds which contain alkoxy groups and comprises an emulsion which contains 2.5 to 25% by weight of an alkoxysilane of the formulaR.sup.1 -Si(OR.sup.2).sub.3whereinR.sup.1 is an alkyl group with 3 to 12 carbon atoms andR.sup.2 is a methyl or ethyl group, 2 to 20% by weight of an alkoxysiloxane of the formula ##STR1## wherein R.sup.3 is an alkyl group with 1 to 6 carbon atomsa is 0.8 to 1.2 andb is 0.2 to 1.2,0.01 to 5% by weight of an emulsifier, 0.01 to 0.1% by weight of fillers with an effective surface area of at least 40 m.sup.2 /g and 49.9 to 95.48% by weight of water. The composition has a long shelf life and, due to its high penetration, a high water-repellent effect on the surface, as well as deep within, all mineral building materials.

Abstract: For purposes of protecting electrical installations against electromagnetic disturbances, especially overvoltages, for instance, as a consequence of lightning strikes, wiring lines laid for connecting individual electrical apparatus are surrounded by a shielding, which is formed by a braiding, consisting of electrically conducting material and which is in connection with connector elements arranged at its ends. The connector elements, as well as an additionally provided terminal, branching and attachment elements, comprise, respectively, a transitional part over which the braiding is pulled and on which it is fastened by means of a clamping element. In addition, further sheaths of a plastic braiding are provided between the electrical shielding and the electrical lines.

Abstract: An endodontic filing tool which can be chucked into a dental tool holder with slight play but secured against rotating movement as well as against axial movement by chucking balls. A circumferential groove is provided at the rearward end of the tool shaft, wherein the circumferential groove is interrupted at at least one location, so that a stop for the chucking ball is formed.

Abstract: A fastening and/or support device for roller bars on support rails which extend transversely of the roller bars, particularly in continuous shelf systems. The device includes locking bars which extend in longitudinal direction of the support rails and can be fastened to the support rails, wherein the ends of the roller bars can be fixed in predetermined locking recesses provided on the locking bars, and wherein the locking recesses are arranged distributed, preferably uniformly, over the longitudinal direction of the locking bar. A head member each is provided between the locking bar and the corresponding end of each roller bar. Each head member has at the underside thereof several locking projections which are spaced from each other at a distance which corresponds to an integer multiple of the difference between two adjacent locking recesses.

Abstract: The invention relates to spacing rings for spacing plates of a viscous coupling, which spacing rings are provided with teeth which correspond to the teeth non-rotatingly receiving the plates, so that during assembly the tooth gaps are filled. This measure simplifies assembly because the plates can be preassembled to form a kind of package.

Abstract: A device for connecting a motor vehicle steering column to a shaft journal of a steering gear train includes a U-shaped coupling piece, the coupling piece is articulated to the steering column for pivotal movement about an axis extending transversely of a first direction of the coupling. The U-shaped coupling piece has a pair of laterally spaced sides connected together by an arch shaped bight section. The sides are spaced apart laterally transversely of the first direction. A lock bolt for retaining the shaft journal in the coupling is secured against turning in one of the sides and has a wedge-shaped surface facing into the space between the sides. The wedge-shaped surface has two bevel sections inclined inwardly into the space between the sides from diagonally opposite points on the outer circumferential periphery of the lock bolt.