an improved wood chipper and storage dump box assembly is provided on a trailer adapted to be towed behind a truck . the dump box is pivotally mounted on the trailer for movement between an upright fill position and a sideways tilted dump position . the brush chipper is mounted on a trailer behind the dump box to discharge chipped brush and material into the dump box through an opening in the back wall . the top of the dump box is open for loading logs and other unchipped material . the dump box includes a discharge opening in one side wall , with a door movable between open and closed positions relative to the discharge opening . hydraulic actuators control movement of the door and tipping of the dump box , and are connected to the hydraulic system of the chipper .