Abstract: A pharmacy shelving array is described which has a plurality of side-by-side, open-faced fixed shelving columns and a plurality of side-by-side, track mounted, roller supported movable shelving units parallel to and closely adjacent to the fixed columns. Tracks lying parallel to the front faces of the open-faced fixed shelving columns and having end stops adjacent their ends are provided. Each movable shelving unit has a back, an open front, sides, a top and a bottom, and a plurality of shelves extending between the sides. A guide adjacent the top and parallel to the track is provided for stabilizing the movable shelving units against tipping. A self-priming deceleration system is provided adjacent the side of each movable shelving unit for engaging a next adjacent shelving unit or end stop for slowing movement of the movable shelving unit as it moves in the direction thereof along the track.