Case-picking operations frequently use high-density pallet flow (or “gravity flow”) rack engineered to hold multiple pallet loads in individual lanes pitched downward. In these systems, forklifts load full pallets of product from the back (or “charging”) end. The pallet loads rest atop a series of rollers or skate wheels. Gravity draws the pallets forward down the slope to the pick-face, or discharging, end. Associates stationed at the discharging end pick split cases from the full pallets. After depleting a pallet of products, removing the empty pallet prompts the subsequent loads in the lane advance forward.
Because the pallets in the lane rest against each other, however, the pallet at the pick-face experiences a substantial amount of force. Known as pallet flow back pressure, this equates to approximately 6% of the full weight of all rear pallets.
3-deep system, 2,500 lb. load. Back pressure = .06 x 2,500 lbs. x 2 pallets = 300 lbs.
That increased force can make it extremely difficult for a picker to lift and remove the front pallet when empty. A worker who tries to do so is at an increased risk of sustaining an ergonomic injury due to repetitive bending, stretching and straining.
Interlocking Pallet Separator Negates Flow Rack Pressure
To negate pallet flow back pressure, an interlocking pallet separator (sometimes referred to as a “hold-back” or “braking” device), can be added to the lanes. This component pops up above the roller or skate wheel tracks to stop and hold the series of pallets behind the one at the pick-face, typically at a distance of 6 to 12 inches. A pallet separator mitigates the forces that prohibit easy removal of the front pallet. After removing the empty pallet, the associate releases a manual latch to advance the pallet flow and allow the next pallet to slide into the pick-face position.
Additionally, pallet separators can be used in deep-lane flow to relieve the pressure otherwise experienced by the lift truck. Likewise, they eliminate the forces that prevent easy removal of the empty pallet. That increases forklift driver productivity and prevents product damage.
For even greater control of pallet movement as each shifts forward in a pallet flow lane, two other accessories exist:
- Speed Controllers: Ensuring that pallets advance at a controlled, steady pace, these braking devices mount below the roller tracks. Alternately, they drop in on top of the wheeled tracks, typically at a single pallet interval. The controllers minimize the risk of product or pallet damage. Further, they help to keep the loads centered in the lane, reducing the risk of a hang-up.
- Ramp Stops: Also referred to as “end stops,” these devices bolt onto the discharge end of the pallet flow rack lane. They slow the advance of the first pallet, stopping it safely and holding it securely at the pick-face.
Discover More Guidelines for Safe Use of Racks
Purchase RMI’s publications “Considerations for the Planning and Use of Industrial Steel Storage Racks” and “Guideline for the Assessment and Repair or Replacement of Damaged Rack.”
