Because high-density pallet flow (also called “gravity flow”) rack is engineered to hold multiple pallet loads in a lane with a downward pitch, they are increasingly popular for use in case-picking operations. Full pallets are loaded from the back, or charging, end atop a series of rollers or skate wheels; the forces of gravity draw the pallets forward to the pick-face, or discharging, end. This allows pickers to split case pick from full pallets.

However, because the pallets in the lane rest against each other, they generate a substantial amount of force on the pallet at the pick-face. This effect, known as pallet flow back pressure, is 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. Attempting to do so has the potential for ergonomic injuries due to repetitive bending, stretching and straining.

To mitigate pallet flow back pressure, a pallet separator (sometimes referred to as a “hold-back” or “braking” device), can be added to the lanes. This interlocking 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. That negates the forces prohibiting the front pallet from being easily removed. To advance the pallet flow, a manual release latch is triggered by the operator, allowing the next pallet to index into pick-face position.

When used in deep-lane flow, the device relieves the pressure otherwise experienced by the lift truck. That increases forklift driver productivity while preventing product damage as it eliminates the forces that prevent easy removal of the empty pallet.

For further control of pallet movement as each indexes forward in a lane, two other accessories can be added:

• Speed Controllers: Braking devices mounted below the roller tracks or dropped in on top of wheeled tracks—typically at a single pallet interval—that ensure pallets advance at a controlled, steady pace. In addition to minimizing the risk of product or pallet damage, the controllers 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 are bolted onto the discharge end of the pallet flow rack lane and slow the advance of the first pallet, stopping it safely and holding it securely at the pick-face.

Looking for more storage rack safety guidelines? 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.