Well-known applications for cassette seals are the sealing of wheel hubs, drive shafts, pinions, and king pin bearings. New specifications have led to further developments, which will be presented in this paper by means of selected examples. One specific new application for cassette seals is the sealing of crank shafts in combustion engines. Several examinations concerning this new development and its possible variations will be made mention of. Emphasis will be laid on the development of a sealing device for the front crankshaft, exposed to dirt, of a heavy duty diesel engine.