Abstract: A drive apparatus for a magnetic disc, particularly a flexible magnetic disc in an envelope, distinguished by a compact design which is achieved by so designing and arranging the linkage between the drive's closure member and disc clamping member that they take up as little room as possible. By designing the linkage in the form of a roller and lever arrangement and arranging them substantially on the central longitudinal axis of the housing of the drive apparatus in the upper portion of the housing, the maximum amount of space is available on either side of the linking means for printed circuit boards and electronic components. In a very advantageous embodiment, the closure member, linkage and clamping member and part of the housing are assembled as a single unit which is ready for fitting.The drive apparatus of the invention can be used for any kind of flexible or rigid magnetic disc.

Abstract: A process for the preparation of 1-amino-4-bromoanthraquinone-2-sulfonic acid or an alkali metal salt thereof by converting 1-aminoanthraquinone (which can be obtained by reduction of 1-nitroanthraquinone with sodium sulfide and/or sodium bisulfide or reaction of the 1-nitroanthraquinone with ammonia) by contacting the same with oleum at a temperature in the range of 90.degree. to 150.degree. C. optionally in the presence of an alkali metal sulfate and thereafter treating the so-sulfonated composition with bromine at a temperature in the range of from 60.degree. to 100.degree. C. 1-amino-4-bromoanthraquinone-2-sulfonic acid or an alkali metal salt thereof can be precipitated from the reaction mixture either by adjusting the sulfuric acid concentration thereof to 60 to 85 percent by weight or by stirring the reaction mixture into water, which optionally contains an alkali metal sulfate.

Abstract: A positioning device for a write/read magnetic head in a magnetic disc data storage device comprising a motor-driven guide disc, with a spiral-shaped guide wall arranged at right angles to the plane of the guide disc, for a guide element in the form of a ball-bearing on a magnetic-head support. Due to the greatly reduced friction it is possible to achieve highly accurate positioning within an extremely brief period of time and with an extremely low power requirement. This device may be used to position the heads in magnetic disc systems for the recording and/or reproduction of analog or digital signals.

Abstract: Pourable elastomer-filler mixtures, optionally containing plasticizer oil, are prepared by an improved process, the process comprising mixing an aqueous emulsion of an elastomer solution with an aqueous dispersion of a filler(s); introducing this mixture into water containing a precipitant(s); precipitating the elastomer-filler mixture while simultaneously removing the elastomer solvent by distillation; separating the thus-precipitated elastomer-filler mixture from the water; and drying the elastomer mixture under constant agitation; and the improvement comprising:Initially emulsifying the elastomer solution in water in the presence of a combination of:(a) 0.01 - 1.0% by weight of an anionic emulsifier, based on the weight of the elastomer solution;(b) 0.001 - 0.1% by weight of a nonionic protective colloid, based on the weight of the elastomer solution; and(c) 0.001 - 0.

Abstract: In a process for the production of pulverulent, tack-free, pourable, filler-containing elastomer particles by precipitating a stable, emulsified, homogeneous mixture of an aqueous elastomer emulsion and an aqueous dispersion of a solid filler for said elastomer in the presence of sodium silicate to form an aqueous suspension of the precipitated elastomer and the filler, the improvement which comprises:(a) precipitating the silicic acid in the aqueous suspension at a pH of 4.0 to 9.0, and then(b) mixing the thus-produced suspension of elastomer, filler and precipitated silicic acid with additional filler in the form of an emulsifier-free aqueous suspension.

Abstract: Discrete, finely divided, tack-free elastomer particles are prepared from a filler-containing aqueous elastomer emulsion containing an aqueous emulsion of an elastomer dissolved in a volatile inert organic solvent having an emulsifying amount of a quaternary ammonium salt cationic surfactant and an aqueous suspension or dispersion of a solid, finely divided elastomer filler, which process comprises gradually introducing the filler-containing aqueous elastomer emulsion into an aqueous alkali silicate solution while maintaining said solution at a pH greater than 2 and simultaneously evaporating the organic solvent to form discrete, finely divided, tack-free elastomer particles.The process can be applied to solid elastomers or to post-polymerization elastomer solutions, and is particularly suitable for preparing pourable, carbon black containing elastomer particles to be formed into shaped objects.

Abstract: A process for the manufacture of a pourable, pulverulent rubber-filler mixture containing plasticiser oil, by combining a filler containing plasticiser oil with an aqueous emulsion of a rubber solution, and precipitating and drying the mixture, wherein the plasticiser oil is adsorptively bound on the finely divided active filler in an amount of from 1 to 100 parts by weight, relative to 100 parts by weight of the filler, the premix thus obtained, which continues to be free-flowing and pulverulent, and consists of filler charged with plasticiser oil, is dispersed in water in the presence of an emulsifier, the resulting dispersion is intimately mixed with an aqueous emulsion of a synthetic rubber solution, this mixture is introduced into an aqueous precipitation bath which is at a temperature of from 40 to 95.degree.