axis x x to drive the journal 20 and the blocking member 22 in rotation about the axis x x and therefore between the passing and blocking positions of the valve the valve 2 includes a fixed body 24 that defines an internal volume v 24 in which the blocking member 22 is received the journal 20 is accommodated in a bore a 26 defined inside a cylindrical element 26 with a circular base that is part of the body 24 of the valve 2 the bore a 26 and the element 26 are also centered relative to the axis x x and disposed radially around the journal 20 the bore a 26 includes a shoulder at the forward end of the bearing 31 i e on the same side as the internal volume v 24 of the body 24 the valve 2 further includes a smooth bearing 31 inserted radially between the journal 20 and the element 26 the bearing 31 is formed of a first facing 32 immobilized against rotation about the journal 20 and a second lining 33 immobilized against rotation in the bore a 26 i e against the element 26 the first lining 32 is a bearing ring and the second lining 33 is a bearing bush the lining 33 surrounds a lining 32 and sliding occurs at the interface between the surfaces.