Stacker crane or pallet shuttle: this is the first major technical decision in any pallet warehouse automation project. Both systems store and retrieve pallets automatically, but their throughput, density and cost profiles are very different. Getting it wrong can be expensive: a stacker crane in a warehouse that needed a shuttle delivers limited throughput; a shuttle in a warehouse that needed a stacker crane carries higher maintenance costs than necessary. This guide breaks down the concrete technical differences to help you determine which one is right for your warehouse.
How each system works: architectural differences
The stacker crane is a crane that moves within a single aisle: it travels horizontally on floor and ceiling rails and raises a telescopic fork that retrieves the pallet from its cell. Each aisle has a dedicated stacker crane, and operation is sequential—one pallet at a time. The pallet shuttle, by contrast, operates inside the rack channel: an autonomous robot enters the channel, picks up the pallet and moves it. Vertical lifts carry the pallets between levels. A single aisle can hold multiple robots working in parallel on different levels. This parallel architecture is the shuttle's fundamental advantage over the stacker crane.
Throughput compared: when the shuttle wins and when it loses
A unit-load stacker crane handles up to 200 pallets/hour in combined cycles per aisle. A shuttle system can exceed 400 pallets/hour in the same aisle when enough robots operate in parallel. On raw throughput, the shuttle wins. However, the stacker crane is more efficient for operations with strict FIFO rotation and high SKU variability: because every cell is directly accessible, it can retrieve any pallet in any position without moving the others. The shuttle operates in LIFO mode within the channels (the last pallet in is the first one out), although 4-way models allow greater access flexibility.
Storage density and footprint
The shuttle is the density champion: deep storage channels let you hold 10, 20 or even 30 pallets deep within the same aisle width a stacker crane occupies. For homogeneous products with a long shelf life (non-perishable foods, raw materials), a shuttle warehouse can store 40-60% more pallets in the same footprint than one built around stacker cranes. For operations with many different SKUs (high heterogeneity), the stacker crane makes better use of the space because every cell is individually accessible with no loss of density.
Total cost of ownership: which is cheaper over 10 years
The stacker crane has a higher upfront investment cost and a more predictable maintenance cost: it is a robust mechanical machine with few moving components. The shuttle has a lower initial cost per aisle but more robots to maintain—across a large fleet, maintenance costs are proportionally higher. Over 10 years, for operations of up to 2 aisles with moderate throughput, the stacker crane usually has a lower TCO. For high-density, high-throughput operations (3+ aisles, more than 800 moves/hour), the shuttle is competitive on TCO and superior on performance.
The choice depends on your operating profile, not the technology
There is no universal winner between the stacker crane and the shuttle. The right choice depends on the number of distinct SKUs, the throughput required, inventory rotation and the space available. STOKA simulates both options using the real data from your warehouse and shows you the comparative 10-year TCO before you make any investment decision.
Frequently asked questions
Can a stacker crane and a shuttle be combined in the same warehouse?
Yes. A very common hybrid configuration uses stacker cranes for zone A aisles (high rotation, many SKUs) and shuttles for zones B/C (low rotation, homogeneous products). The same WCS manages both types of equipment transparently.
Can the pallet shuttle operate in cold storage?
Yes. DELIE shuttle robots have a cold-storage version (-30 °C). The lithium batteries operate in cold conditions thanks to internal heating systems. Battery charging takes place in a temperature-controlled area to extend the life of the pack.
How many aisles are needed for a shuttle to be cost-effective?
In general, the shuttle starts to be more cost-effective than the stacker crane in configurations of 2+ aisles with homogeneous products and low SKU variability. For single aisles with a high product mix, the stacker crane is usually the better technical and economic option.
Does the stacker crane require special civil works?
The floor slab must be level to within ±5 mm over 5 meters and have the load capacity required for the stacker crane rails. It needs no special structural work if the warehouse already has the necessary clear height.