Balls are interposed between respective raceway surfaces of inner and outer ring members, and a seal apparatus is provided between shoulder portions of the inner and outer ring members. Especially, the air-permeable flexible hose can be properly used as a cleaner hose of the discharge circulation type by using it as an outer tube of a double tube. The gearing subassembly and the locking subassembly are directly interconnected. One torsionally elastic member is arranged in the torque flow of each power transmission branch. In some aspects, the invention relates to methods for discovering inhibitors of the Type III secretion system and uses of such inhibitors in the treatment and prevention of disease.