Direct answer. A stacker crane is an automated machine that travels along a narrow aisle between two rows of racking to store and retrieve loads, pallets, totes, or cartons, at height, with no human intervention in the aisle. It's one of the key pieces of equipment in automated storage and retrieval systems (AS/RS) and many goods-to-person installations.
A fixed, guided piece of equipment for very high-density storage
The stacker crane travels along a floor rail (and sometimes an overhead rail on top of the racking for guidance) on a single horizontal axis, within its dedicated aisle. A vertical mast, fitted with a fork or telescopic gripper, lets it reach a load at any level of the racking, often over several dozen meters of height. Unlike a conventional forklift, it only needs a very narrow aisle (just the space for the load, with no maneuvering room for a driver), which allows storage density on a given floor area to be greatly increased.
The stacker crane is fully controlled by the warehouse's IT system (WMS/WCS): it doesn't "navigate" autonomously across several zones like an AGV or AMR, staying confined to its own aisle. This specialization is what sets it apart from mobile robots: an AGV or AMR can move throughout the entire warehouse and change its path as needed, whereas a stacker crane is a fixed piece of equipment with a set path, optimized for a single repeated action at very high throughput. In a goods-to-person installation, the stacker crane is often the component that retrieves the tote or pallet from the racking before moving it, via a conveyor, to the picking station.
FAQ
What's the difference between a stacker crane and a forklift?
A forklift is driven by an operator and can move through several aisles of a warehouse. A stacker crane is a fixed, automated piece of equipment, confined to a single very narrow aisle, with no driver, for storing and retrieving at very high density.
Is a stacker crane an AGV or an AMR?
No: an AGV or AMR moves autonomously across several zones of the warehouse. The stacker crane stays on a rail, in a dedicated aisle. Both categories fall under automation, but with very different mobility logic.
Does operating a stacker crane require CACES certification?
No: the stacker crane is an automated piece of equipment with no ride-on operator, so it doesn't fall within the scope of CACES, which covers truck driving by an operator. Its maintenance and commissioning, however, fall under specific machine-safety rules, to be checked with the integrator.
Related terms
Conveyor · Goods-to-person · AGV · AMR · Fleet manager · Reach truck · Anatomy and technical specs of a handling truck.
To compare the different types of warehouse robots: logistics robot, the types of robots explained.
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