An improved self-unloading spreader has a front end, a back end, and sides defining walls of a container for holding material. The container has at least one opening in one of the walls through which material can move. Inside of the container, longitudinally disposed between the front end and the rear end, is an
auger that can move material in the container to and through the opening. Also inside of the container, adjustably positioned above the
auger, is an adjustable height baffle to control the amount of material the
auger has available to move. Outside of the container, adjacent to the opening, is a transversely mounted conveyer belt for spreading material that flows through the opening. An hydraulic
system powers the auger and allows the hydraulically powered auger to either move material towards the opening or away from the opening. The auger, in combination with the adjustable height baffle, controls the rate at which material is provided to the conveyer
system. A power-take-off
system transfers power to a gear box system that allows bi-directional movement of the transversely mounted conveyer belt so the conveyer system can spread material to either side of the spreader. The speed of the power-take-off system controls the distance to which the conveyer system throws the material to be spread.