Abstract: Water-soluble salt cores are used in molds for the production of hollow moldings by plastic molding. The production of hollow plastic moldings is effected by positioning a water-soluble salt core in a mold, molding a thermoplastic molding material around the salt core and, after solidification of the thermoplastic molding material, washing out the salt core with a water-containing solvent.

Abstract: Water-soluble salt cores are used in molds for the production of hollow moldings by plastic molding. The production of hollow plastic moldings is effected by positioning a water-soluble salt core in a mold, molding a thermoplastic molding material around the salt core and, after solidification of the thermoplastic molding material, washing out the salt core with a water-containing solvent.

Abstract: The present invention relates to a regulating arrangement for metering a supplementary quantity of air for improving the combustion in internal combustion engines or afterburning of exhaust gases. The amount of air entering the regulating arrangement is metered as a function of the engine speed by means of an air pump driven by the engine. Part of the air entering the regulating arrangement is removed and returned depending on predetermined parameters. An auxiliary device responds to an emergency signal for the immediate shutoff of the fuel or fuel-air mixture used in the combustion. The emergency signal is transmitted by means monitoring the fuel-air ratio within substantially narrow tolerance limits of a predetermined threshold value.

Abstract: A control installation for the dosing or proportioning of a secondary air quantity for the improvement of combustion in internal combustion engines, or the afterburning of the exhaust gases of internal combustion engines, including an auxiliary arrangement which is responsive to an emergency signal for effecting the prompt shutting-off of the secondary air. The emergency signal may be initiated in response to a failure in the ignition voltage of the internal combustion engine; an increase in the hydrocarbon content of the exhaust gases; a disparity between the position of the mixture dosing element and the engine rotational speed; the exceeding of a limiting temperature in the exhaust gas manifold; or the exceeding of a limiting temperature in the afterburner.