Abstract: A shaft seal including a reinforcement ring 1 with a lip ring 2 made of a polymeric material which is connected thereto and which is provided with a cylindrical surface 4 surrounding a shaft 3 at a certain distance and with projecting retaining bodies having flow bounding surfaces disposed in radial direction of the aforesaid cylindrical surface, and the aforesaid flow bounding surfaces are associated with the longitudinal direction of the shaft at an acute angle. The free spaces 6 which are enclosed by the cylindrical surface 4, the shaft 3, and the retaining bodies 5 during non-rotation or standstill of the shaft are of capillary-active narrowness and axially completely open in direction toward the space to be sealed as well as in the opposite direction.

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.