Untangling the Terminology of Material Handling: A Pallet Rack Glossary
Apex Offers a Straightforward Pallet Rack Glossary
Clear communication can be a challenge in any industry—but in the world of warehousing and material handling, we’ve found that commonly used terms often aren’t all that common. With so many moving parts in the average facility, it’s essential that everyone on your team shares the same language. Consistent terminology supports better safety, improved productivity, and lower operational costs.
Since Apex spends every day working with pallet rack design and warehouse safety training, we’ve put together a glossary of the terms we use internally to train our own team. You’ll also find helpful links to related product pages and blog posts in case your team members want a quick refresher or more details on common system components and acronyms.
If your team uses specific terms you don’t see listed here, we’d love to hear from you. And if you’d like to speak with a specialist about optimizing your storage system or solving a specific inventory challenge, give us a call. Our experts are ready to help.
Pallet Rack Glossary of Terms
Accumulation Conveyor: A conveyor system that allows products to move forward while pausing at controlled intervals, helping to manage traffic flow and reduce jams or collisions between items.
Automated Guided Vehicles (AGVs): Driverless vehicles powered by sensors, lasers, or cameras to safely navigate a warehouse or manufacturing facility. These robotic machines move pallets, containers, or goods along programmed routes or adapt to real-time conditions.
Automated Mobile Robots (AMRs): These flexible, autonomous robots use advanced navigation systems, cameras, and sensors to complete tasks and navigate around dynamic workspaces. Unlike AGVs, AMRs don’t require fixed guidance paths and can be adapted to suit a variety of warehouse needs including picking, placing, and inventory tracking.
Automated Storage & Retrieval Systems (ASRS): Integrated systems that use robotics and software to automate the movement, storage, and retrieval of items. These solutions help improve space usage and streamline operations, with both semi-automated and fully automated options available.
Back-to-Back Rack: When two pallet rack systems are installed rear-to-rear and joined with row spacers. (See also: Deep-Reach Rack)
Bay: A single segment of a racking or shelving system where an individual pallet or item is stored.
Box Beams: Shelf beams without inset steps, designed with four flat sides for uniform strength and support.
Carton Flow: A gravity-based rack system designed for storing cartons, totes, or individual products in deep lanes. Slightly inclined rollers or wheels allow items to flow smoothly from the load side to the pick side.
Cantilever Rack: A racking structure with arms that extend from a central column, used to store long or bulky materials like lumber, furniture, or pipe.
Column: The vertical upright in a racking structure, located at the front or rear of the frame. Columns may also serve as single posts in systems like pushback or drive-in racks and come in varying thicknesses and profiles to support different load demands.
Connectors: Fittings used to secure roll-formed beams to uprights. Connection styles vary based on the upright’s punch pattern and can include clips, snaps, or bolts.
Deep-Reach Rack: A storage configuration featuring back-to-back rows of two-deep selective racks, requiring specialized forklifts designed for extended reach.
Drive-In Rack: High-density racking that allows forklifts to enter bays and place or retrieve pallets directly from within the structure.
Empty Pallet Return Lanes: Designated lanes that guide empty pallets away from active picking zones to help reduce clutter and improve warehouse safety.
FIFO: Stands for First-In/First-Out—a storage strategy in which the oldest inventory is picked first by loading from the rear and retrieving from the front.
Gravity Conveyor: A power-free conveyor system that moves items along a slight slope or with a push. Best for transporting lighter loads in a low-maintenance, budget-friendly way.
Honeycombing: The loss of storage space caused by partially filled lanes, often occurring in high-density storage setups like Drive-In Rack systems.
LIFO: Stands for Last-In/First-Out—a picking method where the most recently stored inventory is retrieved first.
Pallet Conveyor: A conveyor system with rollers, belts, or chains designed to transport palletized loads efficiently across a warehouse floor.
Pallet Flow: A type of dynamic racking where pallets move by gravity over sloped rollers or tracks. These systems often include guides, brakes, or stops for safety and control.
Pallet Rack: A structural storage system designed for pallets, typically arranged in horizontal rows and vertical tiers. Multiple racking styles exist for different inventory needs.
Pallet Supports: Steel bars placed between beams to stabilize pallets and prevent them from falling through open rack spaces—often used instead of wire decking.
Pick Modules: Multi-level racking systems built for high-volume order picking. These systems combine various storage types to speed up picking while keeping inventory compact and organized.
Pick Tunnel: A pedestrian-access aisle surrounded by multi-deep racking, typically accessed at floor level. Inventory flows into the tunnel via gravity systems, while reserve stock is stored above using push-back or similar racking.
Push Back Rack: A high-density storage system using nested carts that extend backward on rails. As pallets are loaded, the carts roll back; when pallets are removed, the remaining ones move forward automatically.
Rack: A general term for the steel framework—beams and uprights—used to store palletized or bulk materials.
Roll-Formed Rack: Racking components made by bending sheet steel into shape, commonly used for beams, struts, and uprights.
Row Spacers: Devices that connect two back-to-back rack systems, ensuring proper alignment and adding structural support.
Selective Rack: A single-deep pallet racking system that allows direct access to every pallet. It’s the most widely used and cost-efficient solution for general storage.
Shelf Beam: A horizontal support that connects to the uprights and forms the base of a pallet shelf. Types include box beams, top beams, and channel beams.
Shelving: Multi-tiered storage typically used for hand-loaded items—unlike pallet racking, which is accessed with equipment like forklifts.
SKU: Short for Stock Keeping Unit, this identifier is used to track individual inventory items.
Sortation Conveyor: A type of conveyor system that uses sensors, diverters, and belts or rollers to direct items to specific destinations based on size, weight, SKU, or other characteristics.
Step Beams: Shelf beams that include a step along the inside edge, allowing placement of wire decks or pallet supports.
Structural Rack: A heavy-duty racking system built from hot-rolled steel channels or angles, bolted together for strength. In some cases, structural uprights double as building supports, replacing standard vertical beams in the facility.
Transportation Conveyor: A powered conveyor system used to move items between locations with minimal manual handling. Operates using belts, chains, or rollers.
Unsupported Span: The clear horizontal distance between two upright frames without intermediate support. Properly sizing the span is essential to avoid sagging or structural failure under load.
Uprights: The vertical frame of a pallet rack system, consisting of two columns connected by diagonal or horizontal bracing and secured to the floor.
VNA: Stands for Very Narrow Aisle. In these setups, side-loading forklifts are used to access tightly spaced racking, maximizing floor space.
Warehouse Slotting: A method for arranging inventory within a warehouse to boost picking speed and efficiency. Slotting strategies consider product demand, dimensions, and storage needs.
Wire Decks: Wire mesh panels added to selective racking to create a safety shelf under stored items, preventing products or pallets from falling through.
