Industrial pushback rack storage systems store pallet loads on both sides of an aisle at cubic densities approximately 25% to 65% higher than selective racking. That’s because these systems incorporate a series of nested carts that roll atop inclined steel rails. Each lane is typically two to six pallets deep.
Individual pallets are placed on each cart in succession, with the new pallet pushing back the load placed before it. Because the lanes are loaded front to back, they provide last-in/first-out (LIFO) access. This makes pushback rack systems ideal for storing multiple pallets of the same product, particularly fast movers.
Pushback rack relies on the pallet loads themselves to impel each load and cart in the series through the lane upon loading. Conversely, gravity prompts the loads and carts to descend during removal (as opposed to a mechanized device). This operation requires pallet placement to be relatively precise.
Notably, a lane of pallets also generates a significant amount of force, particularly on the load at the pick face. Therefore, it’s important to ensure operators understand the best practices for safe loading and unloading a lane of pushback rack.
Safe Loading (Also Called “Insertion”) Practices
First, it’s important to only load a pushback system with the pallet style or type it was designed for. Not doing so can negatively affect system performance and increases the risk of a pallet misplaced in the lane. Additionally, loads must rest on undamaged pallets. Likewise, securely unitize every load with stretch wrap or other method to prevent products or cases from toppling off during loading or unloading.
To begin the safe and proper placement of the first pallet into a pushback lane, the fork truck must be positioned squarely to the opening. The operator should lift the load approximately 3-4 inches above the top cart, centering the pallet over the cart (or over an optional centered stop device positioned on the lane’s front beam). With slope cart systems best practice is to tilt the forks up slightly to match the pitch of the rail. Once in the properly aligned position, the pallet is inserted into the system until it is properly placed. At that point, the pallet load should be slowly lowered onto the cart to prevent an abrupt impact that may cause the bottom boards to break.
After lowering—but before removing the forks—the operator should confirm proper pallet alignment as instructed by the manufacturer. Then, remove the forks slowly, maintaining the proper angle of alignment to prevent damage to the pallet or the racking.
Safe Insertion of Additional Pallet Loads
To insert additional pallets, raise the next load to a height approximately 4 inches above the cart. Doing so ensures the pallet makes contact with the pallet already loaded in the system ahead of it. It also allows the new pallet to push against the loaded pallet (instead of the load). This prevents product damage and hang-ups.
Next, the previously described process repeats. Place the new pallet load as instructed by the rack manufacturer prior to slowly lowering it and removing the forks. The final pallet placed in the lane will rest on the pushback system’s rails and behind (not on top of) the optional beam pallet stop device if used.
If any resistance is encountered when inserting pallet loads, the loading process should be stopped, and the issue investigated before proceeding. Common causes of hang-ups include improper pallet centering or positioning. These situations can prompt the pallet to snag on another cart or hit the uprights alongside the lane.
Safe Pushback Rack Unloading Practices
For safe and proper removal of a pallet from a pushback lane, first align the forklift square to the rack face. Tilt the forks up slightly to match the upward slope of the system prior to entering the fork openings. Once the pallet is on the forks, lift it about 4 inches prior to backing out of the system.
Critically, the speed of the forklift as it backs out with the load is what controls the descent speed of the subsequent pallets and carts. Therefore, the operator must control load removal to ensure it is no faster than the speed of the subsequent pallets as they flow forward in the lane. If a forklift exits with its load too quickly, the following loads may advance too fast. The resulting collision with the front of the system could cause rack damage. The impact may also jar the load, prompting boxes to come loose and fall. This increases the risk of both injuries and product damage.
Find tips on safe approaches to un-jam pushback rack systems here.
Find More Pushback Rack Safety Guidance
RMI will be presenting a free educational seminar, “Storage Rack Safety 101,” on Wednesday, April 10 at ProMat 2019 in Theater F at 11:15 a.m.
