Abstract: A mobile elevator conveyor, comprising a main support structure (10) mounted on tracks (11), for mobility along an upper level (14) when in use, an elevating conveyor (13) supported on a boom (12) adapted to be extended from a retracted position within the main frame to an extended position outwardly of said main frame. The boom supporting the conveyor is formed from a plurality of boom segments (22), and is adapted, during extension and retraction, to pass over an outwardly and downwardly curving guide frame (29) mounted on said main support structure. The boom segments are hingedly connected at their lower edges such that the boom structure bends downwardly along its bottom chord at the hinges (23) between the boom segments as it moves over the guide frame, and down to a lower level (15). The interaction of the boom segments is such that bending in the opposite direction is resisted so as to form a rigid boom structure.