Conveyors for particulate material

A tubular conveyor assembly comprising a plurality of conveyor tubes (1) through which one or more members (5) are drawn to transport particulate material therethrough, the assembly including a tubular valve (11) positioned with its longitudinal axis generally in line with the direction of flow of material through the valve, and a rotation imparting device for imparting rotation (23) to the valve relative to neighbouring conveyor tubes, at least one elongate aperture (21) formed in the tubular valve through which particulate material can leave the assembly and said rotation imparting device including a driving device arranged for sequentially rotating the tubular valve about its longitudinal axis between positions in which the at least one aperture is in the open or closed position of the valve, said driving device comprising an air cylinder (23) operable to impart linear movement to a gear rack (24) which meshes with and imparts rotational movement to an annular gear wheel (25) carried by the tubular valve.