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The aisle nobody walks into: pallets that store themselves

Automated pallet storage solves two problems at once: the height a forklift cannot reach and the wide aisle that same forklift needs in order to turn. A crane travels inside the aisle, between two racking runs, lifts to the height of the location and leaves or retrieves a full pallet, with nobody inside. STOKA designs, imports, installs, integrates and supports these systems, and we always start with the process: layout and correctly dimensioned racking first, automation only if volume and height justify it.

Tell us your problem

Why does the warehouse fill up while the volume above sits empty?

Because the forklift sets the limits twice over. It needs width to turn, and that width eats a large share of the floor in aisles. It also has a lift ceiling, so everything above that stays empty. You pay rent, roof and climate control for volume you never use.

What is a pallet stacker crane?

In plain terms: it is a crane that lives inside the aisle. It runs on a rail in the floor, guided by another rail at the top, travels to the right column, raises its forks to the height of the location and leaves or retrieves a whole pallet. Nobody enters the aisle while it works. Because the machine never turns, the aisle is dimensioned barely wider than the load; because it climbs on structure rather than on wheels, it reaches far higher than any floor-level equipment. That is the whole trick: less aisle and more height on the same footprint. The system is completed by the racking that houses it, the conveyors that feed it in and out, and the software that decides which pallet goes to which location. This is the version for the full pallet; for the small load unit, meaning cartons, trays and plastic totes, the equivalent is the miniload.

From 7 to 40 metres: the band where the system makes sense

Automated pallet systems work between 7 and 40 metres of storage height. Below that band, racking with a good forklift is almost always the better answer, because the jump in investment finds no volume to pay itself back.

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Inside the band, the gain comes from two directions at once. On height, the densification factor we use as a design reference reaches up to 3 times against conventional selective racking, and that is the ceiling: going higher does not multiply further, because from there the limit is set by something else. On aisles, the machine never turns, so the aisle is dimensioned barely wider than the load and floor that today goes into circulation becomes storage positions instead. Put together, freed floor space reaches up to 66%. Both figures are STOKA design criteria and are recalculated on your own warehouse during the survey.

Cold store: where the arithmetic closes fastest

Stacker cranes work down to −30 °C, so the freezer chamber is home ground. It is also the application where they justify themselves soonest, because the refrigerated cubic metre is the most expensive one in the warehouse: you pay for the floor, you pay for the insulation and you pay for the energy that keeps it cold around the clock.

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As a reference for what the square metre costs before you even chill it, premium industrial rent in Greater Buenos Aires stands at USD 7.33 per square metre per month, and USD 14.52 in the City of Buenos Aires (CBRE, second quarter of 2026). Every square metre you do not need to chill is that figure times twelve, plus energy. On top of that there is what never reaches the spreadsheet: nobody spends the shift inside the chamber, so the cold breaks, the thermal clothing and the staff turnover that every freezer operation knows simply disappear.

What the building has to meet

Three things are measured before anything is drawn. Real clear height, which is not the roof but the lowest interfering point: the underside of a beam, a sprinkler pipe, a cable tray, a light fitting.

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That is what tells you how many levels actually fit. The floor, which has to meet a given flatness and a given permissible load: the stacker crane runs on a rail and works tens of metres up, so an unevenness a forklift would never notice is amplified at the top. The required values are set by the equipment manufacturer according to the system chosen; we measure them on site during the survey and tell you whether the floor complies or what work is needed. And the building itself: columns, doors, loading bays and where goods come in and go out, because the system is not only the crane but also the conveyors that feed it.

The load unit is what rules

The system does not handle goods: it handles load units. It needs a standard pallet, with dimensions and weight inside a narrow range, in good condition and properly stacked.

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A pallet with a broken board, loose film or a carton hanging over the edge is what stops an automated installation, not height or speed. That is why every project includes a profile check at the entry point: a station that verifies dimensions, weight and stability before the pallet enters the aisle, and rejects whatever fails. If you work today with four different pallet sizes and goods that overhang, there is a piece of work to do first, standardising the load unit, and it is worth doing whether you automate or not. When it is the small load unit that is not standardised, the conversation is a different one: there the equivalent for cartons, trays and totes is the miniload.

What decides whether a pallet stacker crane is the answer?

We do not publish model-by-model specification tables: the detailed sheet comes with the assessment, sized against your operation. These are the criteria the choice is made on.

Real clear height, measured to the lowest point
It is measured to the underside of the beam or to whatever interferes, never to the roof. Below 7 metres a pallet system like this one does not fit, and the option to look at is vertical tower storage. Between 7 and 40 metres the system comes into play and the densification factor reaches its 3x ceiling.
Volume per SKU and movement profile
The system pays off with intensive, repetitive and predictable movement of full pallets. Many stock keeping units (SKUs) with very little volume each, or sporadic goods in and out, leave the investment idle for most of the day.
A standardised load unit
One standard pallet, with dimensions, weight and condition inside range. If the goods are too uneven to define that unit, you standardise first and automate afterwards; the other way round has never worked in any warehouse.
Floor: flatness and permissible load
The stacker crane rail demands tolerances an ordinary warehouse floor may not meet. The values are set by the equipment manufacturer according to the system chosen and are verified on site, with instruments, during the survey.
How stable the layout will stay
An automated system is fixed structure: the racking is part of the machine. If the operation is going to move, change sector or redesign its layout within a few years, flexibility is worth more than density.

Engineering for your operation

When is a pallet stacker crane the wrong answer?

Our approach

There are four situations where we say no, and we say it before quoting. First: goods too uneven to define a standard pallet. If every delivery arrives with a different size, a different weight and a different way of stacking, the system spends its day rejecting loads. Second: too few positions. The investment has a floor that does not fall however small the project is, and with few locations the cost per position becomes indefensible. Third: an operation about to change. If in two or three years you will move warehouse, add a new line or redesign the flow, fixed structure ties your hands; racking, which is modified in hours, is the better bet. Fourth: clear height below 7 metres, where this system does not fit; there the conversation is about vertical tower storage or well-dimensioned racking. And a fifth, the most common of all: if the problem is that you cannot find the goods or that inventory never reconciles, that is process, and automating it simply runs the same disorder faster.

Frequently asked questions

How many pallets an hour does the system move?

We do not publish cycles per hour or performance tables, and that is deliberate. Real throughput depends on height, aisle length, number of machines, order sequence and how loads enter and leave. That figure is calculated on your own operation and delivered, already dimensioned, in the technical sheet of the diagnosis.

Does it work in a freezer chamber?

Yes. Stacker cranes work down to −30 °C and it is one of the applications where they justify themselves soonest, because the refrigerated cubic metre is the most expensive one in the warehouse and because nobody has to spend the shift inside it. The chamber and the insulation are designed together with the system from the start, not afterwards.

Can I install it on the floor I already have?

It is verified, not assumed. Flatness, the condition of the joints and permissible load in kilos per square metre all matter. The required values are set by the equipment manufacturer according to the system chosen and are measured on site during the survey, before quoting. If the floor does not comply, the work is sized and becomes part of the project.

How long from signing to running?

Installation takes 3 to 4 months from the purchase order, and the detailed engineering comes before that. The payback we use as a design reference sits between 18 and 36 months, and it is indicative: it is recalculated with your own figures for floor space, headcount and movement during the diagnosis.

Further reading

Other systems

Before automating, measure the warehouse

The on-site survey establishes real clear height, floor flatness and load, load unit and movement profile. With that we deliver layout, technical sheet and quotation. And if racking is enough for you, we will say so.