Abstract: A system for cleaning the floor of a self-unloading trailer of residual particulate material comprises in combination with moving slats of a typical self-unloading trailer three rails each fashioned to be attached to the top of a slat, and a wedge-shaped sweeper having skates on a lower portion to ride along said rails. The sweeper rides along the rails by means of skate assemblies having pawls which may ratcheting along teeth formed in the rails as the sweeper moves rearwardly in the trailer. A control system sends signals to a motor contained within the sweeper to engage and disengage the pawls, and to a winch to draw the sweeper back to a starting position following operation.