Where do thousands of small parts go when floor runs out?
Upwards, in a single enclosed unit.
A vertical tower stacks trays up to the roof and delivers the one you call at a window at waist height. What takes a whole aisle of shelving today fits on a few square metres of floor.
What it is
It is a tall enclosed cabinet full of trays, with a window at operator height. You call an SKU and an internal lift brings the tray to the window; the technical name is vertical lift module (VLM).
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The carousel does the same by rotating a train of containers until the one you need is in front.
In practice
The vertical tower solves the warehouse that ran out of floor but stores small products: many SKUs on little area, with fast access and nobody walking or climbing a ladder. The product comes to the window and the operator stays at the station.
What is a vertical lift module (VLM), and what is a carousel?
The answer when you do not have 7 metres of height
Automated pallet systems work between 7 and 40 metres of height: below that floor the investment does not pay, because there is nowhere to put the height the system needs in order to perform. That describes an enormous number of urban warehouses, industrial mezzanines, workshops and older sheds with 4, 5 or 6 metres of clear height.
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The vertical tower has no such floor: it is dimensioned to whatever height exists. If you have 4 metres, the tower is 4 metres tall and still gives you back most of the floor that shelving occupies today, because inside it the trays sit tight against one another, with no aisles and no manoeuvring space. So when the survey shows low clear height and small goods, the conversation is not about stacker cranes: it is about towers. It works the other way round too: with 12 metres of clear height and pallets, the tower is not your system.
Where it pays off: small, valuable and many SKUs
The profile that performs best is always the same: small parts, many different SKUs and high value per unit. Machinery and automotive spares, workshop tooling, electronic components, medical supplies and consumables, laboratory samples, tooling inserts, and also document archives that must be kept on file but are almost never consulted.
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All of that usually lives today in long aisles of light shelving, where the operator walks, searches by eye, climbs a ladder and occasionally comes back with the wrong part. The tower reverses the whole arrangement: the operator stays at the window and the machine brings the correct tray over, with the exact position lit up on the tray itself. You gain floor surface, but above all you gain search time and accuracy. With locations managed by the software, inventory stops depending on the operator's memory.
Tower or carousel: what the survey looks at
The difference between the two families is the movement. The tower moves trays vertically inside a cabinet and exploits all the available height, so it performs better the higher the roof.
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The carousel rotates a closed train of bins; the horizontal type turns on the floor and the vertical type turns inside a lower cabinet, which suits premises with very low ceilings or where a tall structure cannot be anchored. Order rate is the other criterion: a tower delivers one tray at a time, whereas several units working in parallel, with the operator between them, sustain far more activity. The choice comes out of crossing real clear height, the number of SKUs, the size of the stored unit and order lines per hour at the peak, not at the average. We do that calculation during the survey, and the technical sheet for the chosen machine is delivered with the diagnosis.
What else you gain: lock and key, and goods that stay clean
Two advantages never make the brochure and yet weigh heavily in practice. The first is control: the machine closes under lock and key and access is managed per user, so what sits inside only comes out against a registered request with a name attached to it.
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For expensive spares, tooling that goes missing, medicines or controlled supplies, that is often worth as much as the square metre you save. The second is cleanliness: being a closed cabinet, the goods gather no dust and stay protected, which matters in electronics, in optics and in any sterile product. And the square metre you hand back to the floor has a price: premium industrial rent in the Buenos Aires Metropolitan Area (AMBA) averages USD 7.33 per square metre per month, and in the City of Buenos Aires (CABA) it rises to USD 14.52 (CBRE, Q2 2026). In a small urban warehouse, that arithmetic makes itself.
What is a vertical lift module, and how does it differ from a carousel?
A vertical lift module (VLM) is an enclosed tower with trays stored in two columns, front and back, and a central lift that fetches the requested tray and presents it at an access window at operator height.
Each tray uses only the height its contents need, so the interior volume is used almost without gaps. A vertical carousel rotates a chain of trays, like a Ferris wheel, until the one needed stops in front of the window: simpler and fast for similar parts picked often, but with less use of the interior volume. Against ordinary shelving holding the same parts, the module frees up to 90% of the footprint.
What determines the choice between a tower and a carousel?
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 interfering point, not to the roof: a beam, a sprinkler, a light fitting. The tower is dimensioned to whatever you have, and below 7 metres it is usually the only automated option on the table.
Size and weight of what you store
The unit that goes on the tray has to be small and handled by hand. If you move pallets, reels or heavy packages, the system is a different one: the tower is not the answer, and it is worth knowing that before quoting.
Number of SKUs
The more different and the smaller the SKUs, the better it performs. With few SKUs and high volume each, the tower becomes expensive per position and the same money goes further in shelving or in a high-density system.
Order lines in the peak hour
One window serves one tray at a time. If the picking peak asks for more, the answer is several units in a battery or a different technology altogether. It is dimensioned on the measured peak, never on the monthly average.
Floor and access control
The machine concentrates a lot of load on very little surface, so permissible floor load is verified on site. And if you need traceability per user or a lock-and-key close, that is defined now, together with the management software.
When is a vertical tower the wrong choice?
It does not pay with bulky or heavy loads such as pallets, coils or profiles: the tray is not the right container.
Nor with few SKUs of high volume, because each position in the tower is expensive and that money goes further in racking. And if peak-hour picking exceeds what one window can deliver, the tower becomes the bottleneck.
Frequently asked questions
Can't find your question?Write to us and we reply within one business day.
Tell us about your case01Does it work if my warehouse is only 5 metres high?
Yes, and that is precisely its ground. Automated pallet systems need between 7 and 40 metres to perform, so below that height they drop out of the conversation. The vertical tower is dimensioned to the real clear height you have, measured to the lowest interfering point, and it still gives floor back.
02What is a VLM?
A vertical lift module: an enclosed tower with trays in two columns and an internal lift that brings the requested tray to a window at operator height. It is used for spare parts, tools and small items, and it fits buildings without the height for a stacker crane system.
03VLM or vertical carousel: which one?
Both deliver goods to a window. The VLM uses a lift and stores each tray at the height its contents need; the carousel rotates a fixed chain of trays. The choice depends on what is stored, how often it is picked and the clear height available.
04How many trays does it hold, and how much weight per tray?
That depends on the model, on the available height and on the unit you store, so we do not publish a general table: out of context it leads to buying badly. The ranges are narrowed during the survey with your real dimensions and weights, and the full technical sheet for the chosen machine comes with the diagnosis.
05Does it integrate with my management system?
Yes. The tower runs on its own software, which manages locations and directs the operator, and that software integrates with your warehouse management system or with the enterprise resource planning (ERP) system you already use. The integration is defined in the detailed design, because every installation has its own data map.
06How long does installation take?
For automated systems the lead time is 3 to 4 months from the purchase order, and a tower usually lands at the short end of that range because it arrives pre-assembled and is anchored in place. The exact schedule is closed with the detailed design, depending on the civil works required.
Other systems
Tell us what you store andhow much height you have
The survey establishes real clear height, unit size, the number of SKUs and the picking peak. With that we tell you whether the answer is a tower, a carousel or simply better organised shelving.