Abstract: A sliding collar has claw internal toothing and teeth projecting from at least one of the end surfaces. The individual teeth have lateral surfaces configured as lateral surfaces of a cone segment or as lateral surfaces of a cone segment and one or more truncated-cone segments. The novel geometry of the lateral surfaces which extend outward from the root circle results in both manufacturing technology and functional advantages over sliding collars with known tooth geometries.

Abstract: A sintered selector or sliding sleeve, or gear shift sleeve, has internal claw toothing. The individual teeth are delimited on their ends with secondary surfaces having ends that extend radially inward and outward from the root circle of the inner tooth surfaces. The novel geometry of the secondary surfaces extending radially outward from the root circle provide advantages in the manufacture of such selector sleeves by powder metallurgy, compared with those having prior art tooth geometries.

Abstract: A process for welding sintered, friction-lined foils to each other or to a metallic basic body. Such foils, by definition, have a highly inhomogeneous material structure and are, therefore, poorly weldable by conventional joining methods with the usual process parameters. This applies in particular if the weld has to extend through the foils, for example in resistance spot welding, but the surface of the foil material has to remain largely unaffected in terms of its material properties. The invention describes a process which satisfies the strict requirements both with respect to strength of the welded joint and the material properties. Structural components preferably manufactured according to the process are parts of synchronizing systems in motor vehicle gearboxes.

Abstract: A process for producing from iron materials a sintered molded part which is pore-free in individual zones or boundary zones but porous in the other zones. The process is based on a molded part brought to a residual porosity of about 10% by volume by conventional powder pressing and sintering processes. By additional process steps such as zonal introduction of additional materials or local mechanical recompacting, certain zones or local areas are brought to a residual porosity of 5% by volume or less; at the same time, a closed pore structure is produced in these zones. Under these preconditions, in a final HIP or sintering HIP process step the sintered molded part can be brought to 100% material density in the pretreated zones so that they substantially completely free from pores. The major advantages include local improvement in material properties and calibratability of the finished sintered molded part.

Abstract: A gas-permeable form tool for manufacturing casting and core moulds from hardenable moulding sand includes a heteroporous, open-pore material. The wall of the tool contains a first fine-pore layer region adjacent to the moulding sand with a thickness of about 0.2-2 mm and a material density of about 75% to 95% of theoretical specific density and a pore diameter of about 50 .mu.m. The first fine-pore layer comes in contact with a second, large-pore supporting skeleton having a theoretical material density of less than 80% of theoretical specific density and a median pore diameter of more than 100 .mu.m.

Abstract: A friction clutch or friction brake is provided having a basic body and a friction body portion. The friction body portion can be mass-produced separately from the basic body, using a planar metal sheet-like material which is treated leading to a sintered powder friction facing. The friction clutch has a non-planar friction surface, operating in a box filled with oil as a lubricant. The friction body is applied to the basis body by form-locking friction, friction-gripping and/or material-locking techiques. In a preferred embodiment, the friction clutch or brake is a synchronizing ring and/or a correcting ring for motor vehicle shift gears.The friction clutch or friction brake according to the invention has particularly favorable friction properties, a long service life and low manufacturing costs. In a great number of applications, the shaping of separte draining grooves for expelling the oil when the friction grip is produced between matching components can be omitted.