Abstract: A shaft-rotated throttle disk for use in the intake pipe of an internal combustion engine. The shaft is solid and the disk comprises a body (2) of material around it. The throttle disk offers little resistance to the flowing mixture and allows precise adjustment and regulation of the internal combustion engine upon closing. A seal (4) on the outside of the disk material extends on both sides as far as the shaft (1). The seal can be fully engaged with the intake pipe (3) by rotating the shaft.

Abstract: An annular seal in which a sealing lip of polymeric material is urged under resilient bias against a cylindrical surface of a shaft. The cylindrical surface is provided with saucer-like indentations. The maximum depth of the indentations amounts to 4 to 12 micrometers, and each indentation is surrounded on its entire periphery by adjacent indentations. The distance between centers of the indentations is so small that the adjacent indentations merge with one another to form arrises.

Abstract: A seal for the gap between two relatively rotatable machine parts, in which at least one of the two confronting surfaces is provided with at least one helical groove which has a pumping action toward the sealed space, and in which a preliminary seal is situated ahead of the helical groove on the side facing away from the sealed space. The preliminary seal includes a ring magnet which reaches close to the opposite surface except for a narrow gap. This gap is filled with a ferrofluid, and the radial width of the gap is substantially the same as the distance separating the helical ridges between the helical grooves from the surfaces opposite them.

Abstract: A seal for a magnetizable shaft includes a sealing lip of polymeric material and a preliminary seal on the side facing away from the sealed space. The preliminary seal consists of a ring magnet which surrounds the shaft leaving a gap. A ferrofluid is disposed in this gap.