Push back rack is a popular high density storage solution for warehouses that handle large volumes of inventory and need to store multiple pallets of the same SKU in a relatively small footprint. By allowing pallets to be stored several positions deep while keeping forklift access at the front of the rack, push back systems can increase storage density without requiring forklifts to drive into the storage lanes.

Traditional push back rack systems typically use wheeled carts that travel along pitched rails. While this design has been used successfully for years, newer push back flow rack configurations replace the carts with wheeled rails or rollers. This alternative can provide deeper storage, lower maintenance requirements, and more efficient use of vertical space.

Understanding how these two approaches differ can help warehouse operators determine which deep lane storage configuration is best suited to their facility.

What Is Push Back Rack?

Push back rack is a last in, first out, or LIFO, storage system designed for high volume SKUs. Unlike selective pallet rack, where each pallet location is directly accessible from an aisle, push back rack stores multiple pallets behind one another in a single lane.

The forklift operator loads and retrieves pallets from the same aisle. When a new pallet is placed into the lane, it pushes previously stored pallets farther toward the back. When the front pallet is removed, the pallets behind it move forward toward the picking position.

This design allows a warehouse to store several pallets of the same product in one lane while reducing the amount of aisle space required compared with many conventional storage configurations.

Traditional push back systems commonly store around three to five pallets deep. However, deeper push back flow configurations can extend storage depth considerably, allowing facilities to take greater advantage of available floor space.

How Traditional Push Back Cart Systems Work

A conventional push back system uses individual SKU lanes equipped with pitched rails and wheeled carts. The carts are nested together and extend through the depth of the storage lane.

During loading, the first pallet is placed on the uppermost cart at the front of the lane. The forklift then pushes that pallet backward, causing the cart to move along the rails and exposing the next cart.

The process continues as additional pallets are loaded into the lane. The final pallet generally rests directly on the rails.

When inventory needs to be retrieved, the front pallet is removed with the forklift. The remaining pallets then move forward toward the aisle, positioning the next pallet for retrieval.

This creates an efficient LIFO storage process without requiring the forklift to enter the rack.

The Limitations of Push Back Cart Systems

Traditional cart systems provide useful density, but their design can create limitations when warehouses need deeper storage.

One limitation is storage depth. Conventional push back configurations are often limited to approximately three to five pallets deep. When an operation needs to store larger quantities of the same SKU, it may have to increase the number of rack levels or expand the footprint of the storage system.

Cart height can also affect vertical storage capacity. Because carts are stacked within the system, their profile takes up some of the available vertical space. Once pallet height and the clearance required for forklift handling are considered, the amount of usable vertical space can become restricted.

Another consideration is pallet movement. As pallets are pushed deeper into the lane, rear pallets can create additional pressure against the pallet at the front. In higher rack elevations, this can become a concern when forklift mast capacity and load handling capabilities are factors.

Traditional carts also contain moving wheels and components that can eventually wear or fail. A damaged cart inside a storage lane can create maintenance challenges and potentially interfere with safe pallet movement.

Finally, cart-based systems may place limitations on pallet dimensions because the carts are generally designed around specific pallet lengths and widths.

What Is Push Back Flow Rack?

Push back rack uses the same basic LIFO principle as traditional push back rack but changes the way pallets move through the storage lane.

Instead of relying on wheeled carts traveling along separate rails, push back flow systems can use wheeled rails or rollers running through the depth of the lane. Eliminating the individual carts creates a lower-profile storage system that can support deeper lanes.

This configuration can be particularly valuable for warehouses that need to maximize pallet positions while making efficient use of vertical space.

The lower profile of the flow components means less space is consumed above each beam. This can allow additional storage levels to fit within the same building height or provide more room for pallet clearance at existing levels.

Deep Lane Storage With Push Back Flow

One of the primary advantages of push back flow rack is the ability to create significantly deeper storage lanes.

Deep lane systems can support 12 or more pallets in a single lane when properly designed for the application. This can substantially increase the number of pallet positions available within a warehouse without requiring an equivalent increase in floor space.

Deep storage is especially useful for high volume SKUs where multiple pallets of the same product need to be kept together. Rather than creating individual storage locations for every pallet, several pallets can occupy one deep lane.

This can reduce the amount of aisle space needed per pallet position and improve overall warehouse density.

Making Better Use of Vertical Space

Vertical space is one of the most valuable resources in many warehouses. When a building has significant clear height, using additional vertical levels can dramatically increase storage capacity.

The profile of the storage equipment matters when determining how effectively that height can be used. Traditional carts consume additional space within each level, which can reduce the number of levels that fit within a given building height.

Push back flow rack uses a very low-profile configuration. In some designs, the flow components require only about 1 9/32 inches above the beam. This can free several inches of vertical space at each level.

Those savings may allow a warehouse to add another storage level or increase the depth of its storage lanes while remaining within existing building constraints.

Controlling Pallet Velocity

As storage lanes become deeper, controlling pallet movement becomes increasingly important. Gravity helps move pallets toward the aisle, but uncontrolled movement can create operational and safety concerns.

Push back flow systems can incorporate speed controllers to regulate pallet velocity. This is particularly useful in deep lane applications and when pallet weight requires additional control.

Controlled movement helps prevent pallets from traveling too quickly toward the pick face. It can also make the retrieval process more predictable for forklift operators.

The appropriate speed control should be selected based on pallet weight, lane depth, pallet characteristics, and the overall design of the flow system.

Durability and Maintenance

Reducing the number of moving components can have a positive effect on maintenance requirements.

Traditional push back carts contain wheels that can eventually wear or fail. Because these components operate inside storage lanes, repairs may require additional labor and potentially disrupt the affected storage position.

Push back flow rack uses durable flow rails or rollers instead of individual carts. Depending on the configuration, these components can support substantial loads while requiring comparatively little routine maintenance.

Individual wheels and rollers are also designed with rated capacities appropriate to the application. Proper system design and load distribution remain essential to ensuring that the equipment performs as intended.

Accommodating Different Pallet Sizes

Another advantage of push back flow rack is flexibility in pallet dimensions.

Traditional cart systems may be designed around a uniform pallet size because the carts need to accommodate specific load dimensions. Flow-based designs can provide greater flexibility for operations that handle pallets of varying shapes and sizes.

This can be useful for warehouses with diverse inventory profiles. Instead of designing the entire system around one standardized pallet dimension, different lane configurations can potentially be adapted to the products being stored.

The actual pallet sizes, weights, and load conditions should always be evaluated before finalizing the storage design.

Floor Mounted Push Back Flow Rack

Floor mounting the first level of a push back flow system can provide additional space-saving benefits.

A floor-mounted first level can eliminate the need for certain front and rear cross beams, while also saving vertical space at the lowest storage level. This can be particularly useful when building height is limited or when maximizing every available inch is important.

Floor mounting can also help create a configuration tailored to the specific layout and operational requirements of the facility.

Push Back Rack and Inventory Rotation

Push back rack is traditionally associated with LIFO inventory rotation. This makes it a good fit for products where the newest pallet does not necessarily need to be the first pallet retrieved.

High volume products with relatively stable demand can often benefit from this arrangement. However, inventory requirements can change over time.

One advantage of a flow-based design is that certain configurations can potentially be adapted for FIFO operation if inventory rotation requirements change. This flexibility can provide additional value for facilities that expect their storage or fulfillment strategies to evolve.

The appropriate inventory rotation method should be determined during system design so that pallet movement and lane configuration support the required workflow.

Push Back Rack vs. Other Storage Systems

Push back rack occupies a useful position between highly selective pallet storage and extremely dense storage systems.

Compared with selective rack, push back provides greater pallet density but reduces direct access to individual pallets. Compared with drive-in rack, forklift operators generally remain in the aisle rather than entering the storage structure.

The choice depends heavily on SKU volume, pallet quantities, inventory rotation requirements, and the desired balance between accessibility and density.

For operations storing several pallets of the same SKU, deep lane push back can provide an attractive combination of density and forklift accessibility.

Choosing the Right Push Back Configuration

The best push back rack design depends on the warehouse's inventory profile and physical constraints. Consider the number of pallets stored per SKU, pallet dimensions and weights, required storage depth, available building height, forklift capabilities, and desired inventory rotation.

Traditional cart systems may be appropriate for applications where moderate depth is sufficient and the existing operating model fits a cart-based design.

For facilities seeking deeper lanes, greater vertical efficiency, reduced maintenance, and more flexible pallet accommodation, push back flow rack may provide a stronger alternative.

Improving Warehouse Storage With Deep Lane Push Back Rack

Push back rack continues to be a valuable solution for warehouses that need to increase pallet density without sacrificing convenient forklift access. Traditional cart-based systems provide an established approach to LIFO storage, but their depth, vertical profile, maintenance requirements, and pallet-size limitations can become more significant as storage demands increase.

Push back flow rack addresses many of these challenges by replacing wheeled carts with low-profile flow rails or rollers. The result can be deeper lanes, improved use of vertical space, controlled pallet movement, reduced maintenance, and greater flexibility.

For warehouses handling high volume SKUs, the right push back configuration can make a meaningful difference in how efficiently available space is used. By evaluating inventory requirements, pallet characteristics, building dimensions, and handling equipment before installation, facilities can develop a deep lane storage system that supports both current operations and future growth.