Bearing device null of butterfly valve for exhaust air brake

摘要

PURPOSE:To secure easy opening/closing operation of a valve body by eliminating a foreign matter in an exhaust gas, which adheres to a sliding contact part between a bearing member and a sealring. CONSTITUTION:In an outside recessed groove 8 formed of an outside retainer 7 and a step difference part 5a of a bearing member 5, a seal member 10 is freely fitted, and multiple rough faces, which have triangular cross sections and face in the radiation direction, are formed on the side face, which is slidingly contacted with the step difference face 5b of the seal member 10, so that a foreign matter adhering to the step difference face 5b is scraped off at every opening/closing operation of the valve body 4 and adhesion of the foreign matter can be prevented.