Abstract: In an extrusion head and an extrusion method for the production of a tubular multilayer preform the extrusion head includes at least two feed paths for feeding plasticised plastic material from one or more extruders to an annular passage arrangement. The annular passage arrangement includes mutually concentric annular passages forming mutually separate flow paths for the various layers of the preform. An annular gap nozzle has an annular gap communicating with the annular passage arrangement, and at least one flow passage communicates with an annular passage of the annular passage arrangement, for the introduction of a translucent viewing strip. The flow passage communicates with the annular passage in question upstream of the annular gap in the region of separation of the flow paths.

Abstract: In an extrusion head and an extrusion method for the production of a tubular multilayer preform the extrusion head includes at least two feed paths for feeding plasticised plastic material from one or more extruders to an annular passage arrangement. The annular passage arrangement includes mutually concentric annular passages forming mutually separate flow paths for the various layers of the preform. An annular gap nozzle has an annular gap communicating with the annular passage arrangement, and at least one flow passage communicates with an annular passage of the annular passage arrangement, for the introduction of a translucent viewing strip. The flow passage communicates with the annular passage in question upstream of the annular gap in the region of separation of the flow paths.

Abstract: A double-wall fuel container of plastic material is composed of at least two shell portions which are welded together. The half-shell portions are each in the form of double-wall blow moldings, with a gap being kept free at least in a region-wise manner between the walls of the blow moldings.

Abstract: A double-wall fuel container of plastic material is composed of at least two shell portions which are welded together. The half-shell portions are each in the form of double-wall blow moldings, with a gap being kept free at least in a region-wise manner between the walls of the blow moldings.

Abstract: A gear pump has a housing, a pump shaft supported in a housing wall by a bearing, and a pumping gear supported on the pump shaft which is operable to pump newtonian and non-newtonian liquid of different densities. A relief collection zone is arranged on a low-pressure side of the bearing for collecting leakage liquid passing through the bearing along the shaft. At least two return ducts or bores are provided which connect the collection or relief zone with a suction side of the pump in order to return the collected leakage liquid.

Abstract: In order to cool the slide bearing area for the slidable bearing of a gear pump shaft, a slide bearing bush with a slide bearing area and, in the case of the guiding-through of a shaft, a sealing area extends in one piece integrally to the outside, and a cooling-medium guiding system provided in the bush is connected from the outside. This eliminates all sealing problems for the cooling medium feeding to the slide bearing area.

Abstract: A gear pump for conveying fluid media, particularly viscous media, has tube or collar-type sections on the suction side and/or delivery side for connecting the pump in a weldable manner with additional system components.

Abstract: A gear pump comprises rotors disposed in roller bearings. For the delivery of very viscous polymer meltings, bearings surfaces of at least one of inner races, outer races of the bearings and bearing surfaces of roller elements are made of a steel with a high-temperature stability. Bearing takes place on material pairings consisting of one of S6-5-2 high-speed steel and silicon nitride Si.sub.3 N.sub.4. The roller bearings are either unlubricated or lubricated by a lubricant remaining in the bearing, preferably a solid-substance lubrication. A distance of supported shafts, from a gearwheel face to a supporting area of the shafts, determined by the outer contact point in the roller bearing, is smaller than twice the median diameter of the shafts therealong.

Abstract: To reduce squeeze pressure peaks on meshing rotors of a gear pump, recesses are molded into the product duct wall in the meshing area, on the delivery side and the suction side. The recesses are formed with spherical segments or other continuously curved surfaces.

Abstract: Apparatus and process for handling thermoplastic liquified material is disclosed. A system including an extruder feeding into a degasifying chamber is disposed upstream of a gear pump for pressurizing the material. The extruder gravity delivering, by way of a multiple-billet die, billets to the gears outside of the gear meshing area.

Abstract: A gear pump rotor assembly is disclosed. In order to prevent that the gear toothing is cooled in an unreliable manner, radial heat flow is reduced in the toothing area of the shaft, preferably by means of an insulation air chamber or other insulated section, with respect to the heat flow in other shaft areas to be cooled.

Abstract: A gear pump comprising a housing for housing gear pump rotors in a housing interior, said housing having a housing end at an end face side of the housing through which at least one pump rotor shaft is guided from the housing interior to outside the housing, a shaft bearing in the housing end for rotatably supporting the rotor shaft, and a labyrinth seal in the housing end which in use surrounds the rotor shaft, wherein the shaft bearing is arranged separately from the labyrinth seal at a position spaced axially inward toward the housing interior with respect to the labyrinth seal.