Rack beam
Also called: load beam, step beam, box beam
A rack beam is the horizontal steel member that spans between upright frames in pallet racking and carries the pallets. The distance between the front and rear beams sets the pallet's unsupported span.
In depth: Pallet racking and deflection: rack spans, direction and sag limits
Beams come in pairs at each rack level: one at the front, one at the rear. The pallet rests on both and spans the gap between them.
Common beam types
| Type | Profile | Note |
|---|---|---|
| Step beam | Box section with a stepped ledge | Ledge takes wire decking or pallet supports |
| Box beam | Closed rectangular section | No ledge |
| Structural channel | C-channel | Used in structural (bolted) racking |
What it means for the pallet
- Span: the clear distance between beams is the pallet's unsupported span. PDS examples for a 48 in pallet use 44 in (1118 mm).
- Bearing: the pallet's end boards or blocks bear on the beam faces. Lead boards and blocks take the load and the fork impacts.
- Three-beam support: a center beam shortens the span and raises the pallet's racking load. PDS rates 2-beam and 3-beam support separately.
Beam capacity is separate
The beam's own rating comes from the rack maker. In the US, rack design follows the Rack Manufacturers Institute specification (ANSI MH16.1), which also limits beam deflection. That rating is separate from the pallet's. Both must be adequate.
On a spec sheet or RFQ
Give the beam span (or beam-to-beam distance), the number of beams, beam face width if known, and whether wire decking or pallet supports are installed.
Common confusions
"Beam length" usually means the beam's long dimension along the aisle (the bay width), not the gap the pallet spans. Say "span between front and rear beams" to be clear.
Related
- GlossaryWhat is pallet racking?Pallet racking is a steel storage structure of upright frames and horizontal beams that holds loaded pallets in levels above the floor. The pallet usually spans the gap between two beams, so its racking load rating, not its floor rating, governs.
- GlossarySelective rackSelective rack is the most common pallet racking: one pallet deep from each aisle, so any pallet can be picked without moving another. The pallet rests on a front and rear beam and spans the gap between them.
- GlossaryRacking loadRacking load is the weight a pallet can safely carry while it spans the gap between rack beams with no support underneath. It is usually the lowest of a pallet's ratings and depends on the span, the direction racked and the number of beams.
- GuidesPallet racking and deflection: rack spans, direction and sag limitsIn a rack a pallet spans between two beams with nothing underneath, so it bends. Racked across the length (stringers span about 40 to 44 in on a 48 in pallet) is usually stiffer than across the width (deckboards span about 36 in). Common deflection limits are about 2% of span, or 0.5 in or less for automated storage.
- GlossaryRacked across lengthRacked across length is a support condition where the rack beams support the pallet's two ends and the pallet's length spans the open gap. On a stringer pallet the stringers carry the load across the span.
More in Handling and storage
- GlossaryAutomated storageAutomated storage, often called AS/RS (automated storage and retrieval system), stores and retrieves pallets with stacker cranes, shuttles and conveyors instead of forklift drivers. It needs pallets with tight dimensional tolerances, low deflection (often 0.5 in, 13 mm, or less) and sound bottom decks.
- GlossaryBlock stackingBlock stacking is storing unit loads directly on top of one another on the warehouse floor, in rows and columns, with no racking. The bottom pallet and the packaging carry the whole stack, so static load and box compression strength limit the height.
- GlossaryConveyorA pallet conveyor moves loaded pallets on driven rollers or chains instead of a forklift. The pallet's bottom deck is the running surface, so the orientation of bottom boards, flatness, deflection and condition decide whether it runs reliably.
- GlossaryDrive-in rackA drive-in rack is high-density racking where the forklift drives into a lane and places pallets many deep on continuous rails along each side. The pallet is supported only along two edges, so its capacity across the unsupported direction governs.
- GlossaryEdge protectorAn edge protector, or corner board, is an L-shaped strip of laminated paperboard, plastic or other material placed on the vertical or top edges of a unit load. It spreads strapping and stretch wrap pressure, protects case corners, and can add vertical stacking strength.
- GlossaryFork tinesFork tines are the two steel arms on a forklift or pallet jack that slide into a pallet's openings to lift it. Their width, thickness, length and spacing set the minimum size of the pallet's openings and affect its dynamic load rating.
Last reviewed 2026-09-24. 266 words.