Shuttle vehicles and rails must be designed in a space-saving way, in order to reach a profitable height grid. The height of the rail is decisive for the reachable space utilisation, because the height arises in every storage level and the totes are stored with a greater, vertical distance as actual necessary. Thus, the space utilisation and the storage capacity are less than those of lifting beams or miniloads – also because of the need of vertical conveyors. On the other hand, the floor space required is almost the same. The rail usually features a high integration of functions. It combines the function of positioning, energy transmission, carrying and guidance of the shuttle as well as safety functions. The data transmission is normally done via WiFi or Bluetooth. The rack has to be realized in that way, that it is able to absorb the occurring force of the movement, even in the case of error. Consequently, the costs for this kind of rack are higher than those for systems, which don’t cause forces or only small forces into the rack.
A shuttle storage system consists of the following components:
– Shuttle vehicle with or without lifting functionality (MLS or OLS Shuttle)
– Vertical conveyor
– Railing system
– Transfer conveyors
Shuttle vehicles, which – regarding the design – aren’t bound to a specific aisle, can move themselves autonomous and therefore take functions in different levels or aisles of the rack. Therefore appropriate transfer devices are necessary. Shuttle vehicles can also be the replacement for automated conveyor systems, in order to bridge transport routes outside of the rack. Accordingly, the design of the shuttles must be appropriate for leaving the rack and moving on the industrial floor or on a rail system.
Shuttle storage systems are used to store or to buffer totes, cardboard boxes and shelf boards. Static line racks are referred as shuttle storage system, in which autonomous shuttle vehicles operate. Every single shuttle vehicle operates in one or in several rack levels, but not in all. Shuttles, which operate in several rack levels, feature a lifting function. Vertical conveyors are used to connect the rack levels. Those can either relocate the shuttle vehicles in another rack level or convey the load to the level of the pre-storage area. Shuttle storages are used preferably for highly dynamic applications and are assigned to the automated small-parts warehouses. Thus, they represent an alternative to the conventional storage system with lifting beams – or miniloads. Advantages arise with the possibility to scale the performance of the system by varying the number of shuttles. Hence, it can be reacting to peak demands and changeable capacity utilisations. The loading is done by load handling devices (LHD), as they are known from the miniloads. However, the LHD are optimised in reference to the application of shuttle systems. Therefore, the flexibility concerning different goods is given. Depending on the LHD different rack types must be used.