A rack assembly that is used to load and unload heavy or bulky material on an overhead rack of a truck, van, trailer, or similar vehicle. The rack assembly may include a base assembly, which may be sized to fit a range of vehicles, trailers, and the like. The rack assembly includes a movable part which rolls down over the side of the vehicle and allows improved access to simplify the loading and unloading operations used to secure any material to the rack. The movable part may include a manual handle, or a power assist mechanism, to assist in loading and unloading operations.