A multilevel vertical conveyor system for transporting uncontained case units to and from a multilevel storage structure having an array of vertically stacked storage levels is provided and includes a frame having platform guide members, a drive member connected to the frame, and support platforms coupled to the drive member. The drive member is configured to move the support platforms relative to the frame in a substantially continuous vertical loop, each of the support platforms being configured to support multiple uncontained case units where each of the multiple uncontained case units is disposed at a respective predetermined area of a respective support platform, the support platforms have support members that are guided by guide members substantially throughout a path of the substantially continuous vertical loop, where the support members are guided in three point contact by the guide members substantially throughout the path.