A rotary valve for conveying fluids, powders or granular substances, said rotary valve comprising: a rotor having a rotor shaft and vanes, and a casing having a main body with an interior for housing the rotor within the interior of the casing, said casing comprising a removable casing end plate defining a rotor shaft aperture into which an end portion of the rotor shaft is insertable; wherein said rotary valve comprises a rotor shaft support assembly, said rotor shaft support assembly comprises said removable casing end plate and a bearing assembly for supporting the end portion of the rotor shaft inserted from an inner side of the removable casing end plate into the rotor shaft support assembly and through said rotor shaft aperture of the removable casing end plate, and said rotor shaft support assembly is adjustable to correct a deviation of a pitch of the rotor shaft from a level orientation relative to said removable casing end plate when the rotor shaft is supported at a single end only by the rotor shaft support assembly with the inserted end portion of the rotor shaft supported within the removable casing end plate and the bearing assembly, wherein said rotor shaft support assembly comprises a tail piece, said tail piece comprises a substantially tubular body having inner and outer ends, said end portion of said rotor shaft is removably locatable within said tail piece to be supported within the removable casing end plate and the bearing assembly, characterized in that, said tail piece comprises a flange extending radially outwardly of an outer surface of the substantially tubular body; said bearing assembly is disposed radially around an outer surface of the tail piece, and in that said bearing assembly comprises a bearing housing and inner and outer bearing adjustment rings (110, 114) each in threaded engagement with, and rotatable within, said bearing housing. a rotor having a rotor shaft and vanes, and a casing having a main body with an interior for housing the rotor within the interior of the casing, said casing comprising a removable casing end plate defining a rotor shaft aperture into which an end portion of the rotor shaft is insertable; wherein said rotary valve comprises a rotor shaft support assembly, said rotor shaft support assembly comprises said removable casing end plate and a bearing assembly for supporting the end portion of the rotor shaft inserted from an inner side of the removable casing end plate into the rotor shaft support assembly and through said rotor shaft aperture of the removable casing end plate, and said rotor shaft support assembly is adjustable to correct a deviation of a pitch of the rotor shaft from a level orientation relative to said removable casing end plate when the rotor shaft is supported at a single end only by the rotor shaft support assembly with the inserted end portion of the rotor shaft supported within the removable casing end plate and the bearing assembly, wherein said rotor shaft support assembly comprises a tail piece, said tail piece comprises a substantially tubular body having inner and outer ends, said end portion of said rotor shaft is removably locatable within said tail piece to be supported within the removable casing end plate and the bearing assembly, characterized in that, said tail piece comprises a flange extending radially outwardly of an outer surface of the substantially tubular body; said bearing assembly is disposed radially around an outer surface of the tail piece, and in that said bearing assembly comprises a bearing housing and inner and outer bearing adjustment rings (110, 114) each in threaded engagement with, and rotatable within, said bearing housing.