A storage system comprising a plurality of shelf units movable together through a circuit attached to and moved by a flexible drive such as a chain or belt, while being guided and stabilized in orientation by a separate guide track which track followers, retained by each shelf unit, move to maintain a selected orientation of the shelves within a system support or enclosure. Each shelf unit is removable by the user from engagement of the drive and from the system enclosure permitting replacement of the shelves within the storage system without system disassembly.