Vertical Lift Modules vs. Vertical Carousels: Which One Is Best for Your Storage Needs?

Automated Vertical Lift Modules

A vertical carousel or a vertical lift modules (VLM) are both ideal material handling options to improve the workflow of your warehouse operation.

One of the major challenges in managing warehouse operations is how to optimize the efficiency of the warehouse floor area. In the modern digital era, the complexity of warehouse operations is continually evolving.

It becomes critical to ensure your inventory occupy as little floor space as possible to minimize your overhead costs, without compromising on the efficiency and safety standard of the warehouse operation.

If you’re planning to upgrade your warehouse from manual metal shelving to an automated storage solution you may be weighing your options. With automated vertical storage and retrieval systems, you can increase your warehouse productivity significantly. By eliminating unnecessary walking, hunting, and climbing, you can protect the safety of your operators and reduce any time or overhead wastage, giving you a dramatic increase in your throughput rate.

Both systems promise similar gains in efficiency; they can both move products from your inventory to your operators, instead of forcing your operators to walk up to individual picking stations on shelving or racks.

Vertical lift modules and vertical carousels can improve up to 85% of your warehouse floor space compared to traditional industrial shelving systems.

However, which handling system is the best for your needs? This decision will be determined by what’s important to you.

This guide aims to assist you by explaining what both these automated solutions do, what are their differences, and each systems’ pros and cons.

What are the advantages of a vertical carousel and a vertical lift module?

Both vertical carousels and vertical lift modules are considered automated goods-to-person material handling and retrieval machines. They both provide storage of slow to medium moving items at a high density.

A single machine at 20 feet tall can offer between 5,000 to 7,000 storage locations of approximately 6 x 6 x 4 feet.

They can deliver the required items automatically to a window at waist level height in a few steps. Every single storage enclosure can be locked up securely to prevent unauthorized access.

If your warehouse has a high ceiling, vertical carousels and vertical lift module s allow you to stack them up as high as your ceiling allows, with a minimal footprint.

With these benefits, it’s easy to see how both systems have become an integral part of almost every large warehouse operation.

How do vertical carousels and vertical life modules store goods?

Vertical carousels use a series of bins or trays that are attached on to a chain. This chain is mounted to the side of an industrial shelving rack and is driven by a motor which moves the bins around in an upright looping motion around a track. You can control the direction of the track to retrieve or stow the goods.

An easy way to visualize how vertical carousels work is to think of it as a Ferris wheel, that moves along at the side of a rack.

Vertical lift modules use two pillars of trays that are controlled by a mechanical located at the center of a rack called the inserter/extractor. An integrated inventory software controls this inserter/extractor. With just a push of a button, the inserter/extractor can quickly and automatically find and retrieve a tray from both front and back, then delivers the tray to the operator at a comfortable ergonomic height.

Vertical Carousels

Comparing Vertical Carousels and Vertical Lift Modules

Footprint space

Both machines share a similar width on the ground. In terms of depth, vertical lift modules are nearly two times deeper than vertical carousels. Ideally, you won’t want the trays to be too deep due to ergonomic reasons. Otherwise, the operator will have a hard time retrieving the items.

You’ll also need to consider the average size of your product, as vertical lift modules are more suitable for larger products.

Most vertical lift module units are approximately 5 -15 feet long by 7 to 10 feet deep. The storage trays tend to be around 4 to 13 feet wide by 2 to 3 feet deep, allowing you to product height of just over 28 inches.

On the other hand, vertical carousels are approximately 6 to 13 feet wide by 5 feet deep. They are mostly designed for moving smaller goods, with the bins measuring from 4 to 12 feet wide by 16 to 24 inches deep, which makes it suitable for moving goods with a max height of 18.5 inches.


Most vertical lift modules come as low as 8 feet but can be stacked up to 100 feet high. Vertical carousels are slightly shorter at just 7 feet, and can only be stacked up to 32-feet tall.

Even though both systems are designed to reach as high as your ceiling allows, you shouldn’t do so unless it’s necessary. The higher you stack your goods, the longer the retrieval time. This means you need to determine the right mix of storage space savings and workflow speed.

Load Capacities

Many modern vertical carousels are capable of handling less than 1,430 pounds per bin. Vertical lift modules can be fitted with trays that can bear 2,200 or fewer pounds of load.

With additional lift-assist equipment fitted onto your vertical lift module, you can move heavier loads around with greater ease.

This is the key difference between both systems. Vertical carousels are harder to outfit with ergonomic cranes and lifts, so if you are storing mostly heavy loads, a vertical lift module may be a better option.

Operation speeds

Most of the operational speed of most automated systems like vertical carousels and vertical lift modules largely depends on the type of application.

The configuration of each machine, such as the unit height, the order profile per customer (single order vs. bulk order, etc.) can affect the throughput rate.

With vertical carousels, you can achieve a rate of 400 items per hour, and with vertical lift modules, you can get a throughput rate of up to 350 items per hour, depending on your configuration.


To achieve top throughput speed, both vertical carousels and vertical lift modules have to be equipped with options such as pick-to-light.

These devices are placed inside the retrieval window and light up when needed, telling the operator where the required items are located so he or she can retrieve it quickly with little to no search time.


Another critical implementation to increase your throughput speed is the process of slotting.

By regularly going through your entire inventory data, filtering out items that are commonly picked together simultaneously, optimizing the ideal position to store each item, you can achieve a higher throughput speed. This process should ideally be implemented as early as possible before your inventory starts to pile up.

A well-slotted system will position the most commonly picked items together on the same carrier. This allows the operator to make more picks on each level before moving on to the next, creating shorter travel time and cutting the overall processing time.

In a well optimized vertical lift module setup, the items that are most often picked are placed closest to the window to allow inserter/extractor to function with minimal travel distance and time.

Whereas in a vertical carousel setup, the carrier trays holding the items that are most frequently picked are placed next to each other, so the chain does not need to move too far to gather all the required items.

With vertical lift modules and vertical carousels, there are many more ways to optimize your throughput rates, such as multi-colored picking or cross picking to ramp up your process flow.

Vertical Carousels

Vertical Lift Modules and Vertical Carousels – Which One Is Right for Me?

The next step is to decide which system is better suited for your warehouse storage operation.

Product mix

As both systems store goods in a different manner, the weight and size of your warehouse goods, and how you mix them are the primary deciding factors on which system you adopt.

Vertical lift modules are typically more complex than your standard vertical carousels as vertical lift modules use a sensor that detects how high up your goods are stored in the individual storage trays.

The integrated software calculates the appropriate coordinates of height and distance, then moves the vertical lift module towards store the trays as required.

With vertical lift modules, you can store your goods as closely as one inch apart so you can maximize the number of goods you store within an area. For example, if the longest item in your inventory is 5.6 inches wide, a vertical lift module can store the item within a 6-inch space within the shelving system.

If that item is removed and the subsequent longest item remaining in the tray measures 3.2 inches wide the vertical lift module will know how to slot it at a 4-inch long item, thus maximizing your storage space to provide you the maximum storage density on your storage rack.

For vertical carousels, the bins are spaced equally in fixed locations.

You can adjust the height and width of each shelf level individually, but they need to be adjusted manually, similar to wire shelving. Because any inventory airspace is wasted space, it’s vital to know the minimum heights of your goods beforehand to cut down travel distance for the carrier tray.

This means that vertical carousels are suitable for storing goods that are of a regular height of approximately 8 inches and under, with little to no height fluctuations.

To maximize your storage density, you can subdivide each unit vertically or horizontally to separate your products for organization and slotting purposes.

However, to adjust those dividers would require time and effort. You would need to manually remove everything from the shelves, remove the bolts on the dividers, make the necessary adjustments before bolting them back in position.

If your inventory type changes regularly enough to necessitate a brand new bin configuration, then you will find yourself spending lots of labor hours to improve your storage density.

Therefore vertical lift modules are a better option if your product mix constantly fluctuates.

Which one do I need?

Due to the difference in operation, construction and handling of goods, vertical carousels, and vertical lift modules offer advantages for different types of purposes.

When you are deciding which machine is suitable for your warehouse operation, please keep in mind the following points:

Select a vertical carousel when:

  • Your warehouse ceiling height is less than 25 feet.
  • The various goods stored in your warehouse have similar dimensions.
  • Your products are not too heavy and can be lifted by hand without assistance.

Whereas vertical lift modules are a great solution if:

  • Your warehouse ceiling height is 100 feet high.
  • You store a variety of goods with different dimensions and weight.

Your business changes inventory mix regularly.

Your goods are too heavy to lift by hand and require assistance to lift, so the operator can safely move your goods from one place to another.

Closing thoughts

Choosing the appropriate industrial shelving system is not that challenging once you understand how each type of technology works. Implementing a vertical carousel or a vertical lift module into your warehouse operation is a significant investment.

Therefore, before you finalize your decision on either choice, it’s highly recommended you speak to other warehouse managers to learn more about the benefits and drawbacks of each system.

Alternatively, you can reach out to an expert consultant at Shelving + Rack Systems, Inc. who can answer any queries you may still have.

Both the vertical lift modules and vertical carousel require periodic maintenance to ensure smooth operation. They may also need to meet to be compliant to regulatory safety standards such as so that your operators can work with them safely.

Contact us today and let us help you determine the most efficient and effective systems to improve the overall productivity of your warehouse, distribution or commercial operation.