Gravity Flow Racks: Are They Right for My Project?

If you’re looking for storage systems for your warehouse, you’ve probably come across the term gravity flow racks. Also called pallet flow rack, gravity flow pallet rack, flow through rack, or simply flow rack, this high-density storage system is one of the most efficient ways to move large volumes of product through a warehouse. But is it right for your project? This guide covers everything you need to know: how gravity flow racking works, the benefits, the two main types (pallet flow and carton flow), real-world applications, and how to know if it’s the right fit.

Gravity flow racks are a FIFO (first in, first out) warehouse storage system that uses gravity, rather than mechanical power, to move inventory from the loading end of a rack lane to the pick face at the opposite end. The basic concept is similar to a conveyor belt: pallets or cartons are loaded at the back of a lane and gently travel forward on rollers or wheels until they reach a stopping mechanism at the front.

Each time a unit is removed from the front of a lane, everything behind it automatically advances one position. This continuous, self-managing flow of inventory makes gravity flow racking systems one of the best options for warehouses with high-volume throughput and consistent SKU movement.

Gravity flow systems are made up of two main components:

1. The rack structure: pallet rack uprights and beams that form the physical system
2. The flow components: wheels, rollers, speed controllers, and brakes that regulate the movement of pallets or cartons through the lane

There are two different categories of gravity flow racks, each designed for a different scale of product:

Pallet Flow Rack

Pallet flow rack is designed to move full palletized loads. Pallets are loaded by forklift at the rear (input) aisle and ride down the inclined lane on full-width rollers or pallet flow wheels toward the front (output) aisle. Speed control wheels and braking mechanisms regulate the pace so pallets arrive gently at the pick face without damage.

Pallet flow systems can accommodate a wide range of pallet depths. For example, a 13-deep pallet flow configuration (a common setup for cold storage environments) allows operators to store exactly one-half truckload per pallet row. Side-by-side rows can then hold a full truckload (26 pallets), making the most of every square foot of expensive freezer or cooler space.

Carton Flow Rack

Carton flow rack, sometimes called carton flow racking or pick flow rack, operates on the same gravity-fed principle but is designed for individual cartons, boxes, or cases instead of full pallets. Carton flow lanes usually integrate directly with shelving-height systems and are a popular choice in order fulfillment, e-commerce, and piece-pick operations where workers need fast access to lots of SKUs.

While pallet flow offers large-volume pallet storage, carton flow is great for high-velocity, small-unit picking. Both systems optimize space, reduce the need for additional aisles, and keep inventory automatically rotated on a FIFO basis.

The mechanics of a gravity flow pallet storage system are straightforward:

1. Load: A forklift operator places a pallet at the back (elevated) end of the rack lane.
2. Flow: The pallet travels forward on rollers or pallet flow wheels, moving by gravity down the slightly inclined lane.
3. Stop: A stopping mechanism at the front of the lane holds the lead pallet at the pick face, preventing it from rolling off.
4. Pick & Advance: When the front pallet is removed, all pallets behind it automatically advance one position forward.
5. Replenish: New pallets can be loaded at the back simultaneously while picking continues at the front. This allows for uninterrupted inventory rotation.

This separation of the loading and unloading aisles is a major perk of gravity flow systems and one of the reasons they’re so efficient for high-throughput operations. Here’s a short clip that shows pallet flow in action:

Pallet Flow Track Options: Wheels vs. Full-Width Rollers

Not all pallet flow tracks are the same. The two most common styles are wheel-based flow track and full-width roller systems (such as Interroll full-width rollers). The right choice depends on your pallet type.

Wheel-based track works well with standard wood pallets that have solid deck boards to ride on. However, if your operation uses plastic pallets with voids or “boards,” wheel track may not be the smoothest ride. In one cold storage project completed by AK Material Handling Systems, testing initially pointed toward wheel track, but the plastic pallet’s shape caused irregular movement. Full-width Interroll rollers solved the problem by providing continuous surface contact regardless of pallet construction.

This is why pallet testing is a critical step in designing any pallet flow system, especially those with non-standard pallet types or deeper lanes.

Pallet Flow Stop Options: Controlling the Pick Face

How pallets stop at the front of a lane is just as important as how they flow from point A to point B. The stopping mechanism at the pick face determines how safely and smoothly the lead pallet is removed and how the next pallet in the lane is held in position during picking. There are several common stop options used in pallet flow systems:

Single-pallet stop (standard). The most common configuration. A single stopping device (typically a fixed or spring-loaded stop mounted at the front of the lane) holds the lead pallet in place until a forklift removes it. Once the lead pallet is removed, the next pallet advances and contacts the stop. This setup is straightforward, reliable, and works well for most standard applications.

Dual-pallet stop (two-position stop). A dual-pallet stop system uses two stopping points near the front of the lane: a primary stop that holds the lead pallet and a secondary stop that captures the second pallet and holds it back while the lead pallet is being removed. This prevents the second pallet from rolling into the aisle or colliding with the forklift during picking. Dual-pallet stops are strongly recommended for heavier pallets and deeper lane configurations where the momentum of advancing pallets could create impact issues at the pick face.

Pallet separator/entry stop. In some designs, a stop or separator is also installed at the load (entry) end of the lane to control pallet entry into the system. This is most common on very deep lanes where managing the pallet queue from both ends improves system flow and reduces the risk of pallet pile-ups or mid-lane jams.

Pallet retainer. A pallet retainer is a safety device that adds extra security to the lead pallet so that it does not roll or tip with accidental contact. This is a valuable safety feature in high-traffic pick environments where bumps or collisions are more common. Pallet retainers secure the lead pallet until it is intentionally removed.

The right stop configuration depends on your pallet weight, lane depth, pick frequency, and the type of forklift or equipment being used at the pick face. As with track selection, this is a design decision that should be made with your pallet flow system supplier. Ideally, the track and stop options would be validated during pallet testing before the system is finalized.

Gravity flow racking can significantly improve warehouse operations in the right application. Here’s a breakdown of the benefits:

• Maximized cube utilization. Gravity flow systems only need two aisles: one for loading, one for unloading. Compared to traditional selective rack, which needs an aisle for every row, gravity flow dramatically reduces the amount of floor space dedicated to forklift travel and opens up significantly more storage room.
• Automatic FIFO inventory rotation. Because pallets or cartons always flow from back to front and are picked from the front, first-in-first-out rotation happens automatically. This is essential for perishable goods like food, beverage, pharmaceuticals, and frozen products, where product freshness and expiration dates are factors.
• High-volume SKU movement. Gravity flow racks are designed for large-volume movement of a single SKU. Pallets can be loaded and unloaded simultaneously, keeping product moving without slowdowns or workflow conflicts between loading and picking crews.
• Reduced labor. The self-advancing nature of gravity flow systems means workers spend less time handling inventory. Fewer forklift moves reduce labor costs while increasing throughput.
• Improved worker safety. Because loading and unloading happen at opposite ends of the system, pickers are kept safely away from forklifts. This physical separation reduces the risk of forklift-pedestrian incidents, which are a leading cause of warehouse injuries.
• Fast replenishment without interrupting picking. New inventory can be loaded at the back while picking continues at the front. This is especially important for high-demand distribution and fulfillment centers where downtime can cost you.
• High-density cold storage. For refrigerated and frozen warehouses where every cubic foot has value, gravity flow pallet rack systems make the most of the expensive space. Deep-lane configurations combined with FIFO rotation make them an ideal solution for food and beverage cold storage applications.

Gravity flow systems aren’t the right answer for every warehouse, but for operations that meet the right criteria, they’re hard to beat. Here are the key questions to ask:

• Do you have high-volume movement of a limited number of SKUs? Gravity flow systems deliver the most value when you’re moving large quantities of the same product. Operations with hundreds of low-velocity SKUs may get better use out of selective or push-back racking.
• Is FIFO inventory rotation important to your operation? If you work with perishable products, pharmaceuticals, food and beverage, or any inventory with expiration dates, FIFO rotation isn’t optional; it’s a compliance and quality requirement. 
• Are you trying to maximize storage density? If you’re paying for expensive cold storage space, or if your warehouse is simply running out of room, the two-aisle configuration of a pallet flow system can maximize your pallet positions per square foot.
• Do you need simultaneous loading and unloading? Operations that need to replenish and pick at the same time (busy distribution centers, food production facilities, 3PL operations) benefit greatly from the separated input/output aisles of a flow rack system.
• What type of pallets are you using? As mentioned above, pallet construction matters. Plastic pallets, non-standard pallet profiles, or heavily loaded pallets may require specific roller or wheel configurations. Always have your pallets tested before finalizing the system design.

Industries That Commonly Use Gravity Flow Racks

• Food and beverage: FIFO rotation keeps product fresh, and the storage density helps maximize freezer and cooler ROI
• Pharmaceutical and healthcare: expiration date compliance needs reliable FIFO rotation
• Distribution centers: high-throughput applications benefit from simultaneous loading/unloading 
• E-commerce and fulfillment: carton flow rack accelerates order picking and reduces labor
• Manufacturing: a continuous flow of materials to production lines helps prevent interruptions
• Cold storage and refrigeration: high-density storage in temperature-controlled environments

One of AK Material Handling Systems’ completed gravity flow rack installations illustrates exactly what this type of system can do in a demanding environment. The project involved designing, supplying, and installing a FRAZIER 13-deep pallet flow structural rack with Interroll full-width rollers for a client in the frozen food industry.

The client needed to maximize freezer warehouse space while meeting high pick demands. The 13-deep configuration allowed them to store exactly one-half truckload per pallet row, with side-by-side rows capable of holding a full truckload of 26 pallets. To handle single-pallet SKUs and LTL shipments, selective rack was added along the perimeter of the freezer.

The full-width Interroll roller track was chosen instead of a standard wheel track because the client’s 48″ x 48″ plastic pallets had a void profile that prevented smooth movement on wheels alone. Pallet testing was conducted during the design phase (a best practice AK follows on all deep-lane systems) and confirmed that full-width rollers were the right choice for this application.

Above and beyond density, the FIFO nature of the gravity flow system gave the client automatic product rotation. This ensured their frozen baked goods were always picked in the right order and stayed fresh.

Every warehouse is different, and the success of a gravity flow system depends on careful planning. Here are the key variables to work through before choosing a system:

• Lane depth: How many pallet positions deep do you need per lane? More depth = more density, but also requires pallet testing and more precise speed control.
• Pallet type and size: Standard wood, plastic, or custom? Pallet profile affects roller/wheel selection.
• Load weight: Heavier loads require different or additional speed control components.
• Facility layout: Ceiling height, column spacing, and available floor space all influence system design.
• Temperature environment: Cold storage and freezer applications require components rated for low temps.
• Integration with other rack types: Many installations combine pallet flow lanes with other racking or shelving systems.

Working with an experienced material handling systems partner to design your layout is the best way to make sure your gravity flow rack system performs as expected from day one.

At AK Material Handling Systems, we design, supply, and install pallet flow rack and carton flow rack systems for warehouses of all types and sizes. From cold storage to distribution centers to food and beverage operations, our design team has the expertise to help you find out whether a gravity flow racking system is the right fit—and to design one that makes the most of your space.

Get a quote today or call us at (800) 722-5908 to get started.

Related Resources:

• Pallet Flow Rack
• Carton Flow Rack
• Cold Storage Rafcking Solutions
• Warehouse Layout Design
• Pallet Rack Systems Overview