Abstract: A gravel delivery truck is disclosed, which carries a moving belt conveyor, on a boom that can swing over the delivery site. The boom is foldable for stowage on the truck. The boom includes a foldable extension, hinged to the main length of the boom. For stowage, the extension is doubled over the main length, and the main length is placed lengthwise, behind the driver's cab, down one side of the truck, and over the rear wheels. The folded-over extension fits into the space ahead of the rear wheels, underneath the main length. The layout of the hinge joint is such that, during folding of the boom, the total length of the run of the belt remains the same. The belt can be kept running, and delivering, at all angles of fold of the boom, and even while the boom is being folded.