Abstract: A machine tool comprising a third carriage which is guided along a circular cylindrical guide of a second carriage by means of a static fluid bearing and which can thus rotate about an axis of rotation which coincides with a centerline of the circular cylindrical guide. A working point of a tool fastened to the third carriage lies on the axis of rotation so that an angular adjustment of the tool effected by rotation of the third carriage can take place independently of a position adjustment of the working point effected by a displacement of the second carriage and a first carriage. The machine tool can be used for the processing of surfaces, in particular in the manufacture of linear and circular Fresnel lenses for projection television screens by means of a cutting tool.

Abstract: A method of manufacturing a master for projection screens, according to which a pattern of parallel rectilinear grooves and ribs is formed on one side of a plate of machinable material by a slotting operation performed by means of a profile chisel. The grooves (33) are formed in several different tooling steps, with several grooves being tooled simultaneously. The profile chisel is of multiple construction and is composed of three subchisels, i.e. a precutting chisel, a cutting chisel (13) and a finishing chisel.

Abstract: A method of manufacturing a master for projection screens, according to which a pattern of parallel rectilinear grooves (31) and ribs (31) is formed on one side of a plate of machinable material by a slotting operation performed by means of a profile chisel. The grooves (33) are formed in several different tooling steps with, several grooves being tooled simultaneously. The profile chisel is of multiple construction and is composed of three subchisels, i.e. a precutting chisel, a cutting chisel (13) and a finishing chisel.

Abstract: The invention relates to a friction-disk transmission with a first shaft (19) and a coaxial second shaft (23) which are rotatable about a common axis of rotation (Z). The first shaft (19) is being coupled with a disk (1) which is tilted with respect to the axis of rotation (Z) and engages with friction a disk-shaped supporting member (11) secured to the second shaft (23) and rotatable about the axis of rotation (Z). The disk (1) is supported by an annular spring (3) and is tiltable about two axes (X, Y) which intersect each other perpendicularly and are located in a plane at right angles to the axis of rotation (Z). The tilting point (P) is located substantially at the point of intersection of the X-, Y- and Z-axes. The rotation of the disk (1) about the Z-axis is prevented by the annular spring (3).The friction-disk transmission can be used in apparatus requiring comparatively large transmission ratios, for example if a vacuum-tight separation is desired between the first and the second shaft.

Abstract: A positioning device having a plate-shaped carrier (5) which is displaceable in a horizontal plane and which is journalled on a table (1) and on which is exerted a pressure and tensile force, respectively, by means of at least two translation drives (11, 13). The translation drives (11, 13) are coupled to the carrier (5) by means of horizontally operating static thrust and tensile bearings, respectively (33 to 41, 49), which transfer via a viscous medium in a contactless manner pressure and tensile forces respectively, between the carrier (5) and the translation drives (11, 13). The contactless bearings (33 to 41, 49) are pre-stressed with a force which is larger than the maximum occurring tensile force between the drives (11, 13) and the carrier (5). Thus, a substantially frictionless coupling is obtained between the drives (11, 13) and the carrier (5). This coupling acts at the same time as a guide for the carrier (5).

Abstract: A shaving unit for a dry-shaving apparatus comprises an external first cutting member with an annular wall portion formed with hair-entry apertures, and a second internal cutting member which is cooperable with the first cutting member and which comprises a ring of cutters which second cutting member can be driven relative to the first cutting member with an oscillatory rotational movement. The first and second cutting members are interconnected by at least two resilient elements, each of which extends substantially radially of the rotational axis of the second cutting member and has an end connected to the first cutting member and an end connected to the second cutting member. The elastic properties of the resilient elements are such as to permit the oscillatory rotational movement of the second cutting member, but the resilient elements are rigid in directions extending substantially parallel to and radially of the rotational axis of the second cutting member.

Abstract: A system for recording/reading information, comprising interchangeable disc units and a drive unit. Each disc unit comprises a disc pack with at least one information disc which is contained in an enclosure comprising two covers which can move relative to each other and which are interconnected by connecting means. The drive unit comprises means for supporting and driving the information-disc pack and means for recording/reading the information on the information discs, means for releasing the connection between the covers, and means for moving the covers relative to each other.

Abstract: A reduction drive having a drivable first structural member which presses a number of bodies of revolution against at least one thin intermediate plate. The intermediate plate is connected to the output of the drive and is supported by a second structural member. The material of the intermediate plate has a modulus of elasticity at least equal to that of the second structural member, and the bodies of revolution are pressed with sufficient force to locally but elastically deform the plate and second member.