Shuttle system

A small battery-powered vehicle runs on rails on each level of a rack, takes a bin or a pallet from its place and brings it to a lift at the end of the aisle. Several vehicles work in the same aisle at the same time, so a busy aisle is not held up by a single machine. A rack served this way is called a shuttle system.

There are shuttles for bins and cartons, and shuttles for pallets that drive into deep lanes under the pallets to store them several deep. A lift carries each load between the levels and the station at the end of the aisle, and that station becomes the busy point to watch in the design.

Because each level has its own vehicle, capacity can often be added by adding shuttles rather than rebuilding the aisle.

When it pays off

It pays off when many orders need many bins an hour from a steady range and a single crane per aisle would be the bottleneck. It also suits operations whose throughput is likely to grow, since vehicles can be added. It pays off less in small operations, where a simpler mini-load or a manual solution is enough, and for ranges whose packaging varies so much that standard bins do not fit.

What the warehouse system does with it

The warehouse system, or the control layer above the machine, sends retrieve tasks naming the container, the destination and the priority. The shuttle controller then plans which vehicle and which lift to use; that planning stays inside the machine control. Back comes a confirmation at each handover point, and a fault if a container is stuck. The WMS keeps the stock and the order; the machine keeps the physical position of every container.

Who makes it

Gebhardt, Knapp, Mecalux, Movu, Stöcklin, TGW

In alphabetical order. Not a ranking or a recommendation.