Fixed conveyor slats (12) in the nature of beams extend over a window in support framework (53, 100, 102, 116, 118) for the movable and fixed slats (10, 12) in a reciprocating slat conveyor. The fixed slats (12) support the movable slats (20), including in the region of the window. The movable slats (10) are in the nature of box beams, providing them with strength and stiffness in the region of the window. At the rear end of the conveyor, the movable slats (10) move onto support brackets (120) which prevent the rear end portions of the slats (10) from being damaged when they are in a position overhanging a rear wall (84) and material is dropped from above down onto the rear end portions of the slats (10).