Come Full Circle as We Dial In on Push-Back Rack Wheels

You Have Options When It Comes to Push-Back Rack Wheels

The invention of the wheel was nothing short of life-altering. It was instrumental to the advancement of ancient society. Cut to today, and you might say that things are still on a roll.  A look inside a modern warehouse would demonstrate wheeled efficiency in several forms, from multi-ton vehicles to roller conveyor and wheeled pallet storage. 

The popular high-density push-back rack system relies on wheeled carts to dynamically store palletized inventory. Dynamic storage is an efficiency booster for high-volume and fast and moderate-turnover stock because it relies very little on manpower, condenses the storage footprint, and organizes SKUs in designated lanes for faster, more accurate put-away and picking.

Benefits of Push-Back Rack

• Store more pallets in less space
• 100% SKU selectivity per lane – same as selective rack
• Automatic pick face replenishment – pallets flow to aisle face 
• Store 2 to upwards of 6 pallets deep per lane
• SKUs segmented per lane – fast, accurate selection

Push-back rack relies on enveloping wheeled carts positioned on tracks within the lane. The carts are pushed back into the storage lane as pallets are loaded and then flow forward to the pick aisle as pallets are extracted. Take a look at how smoothly a push-back lane functions:

Since push-back relies so heavily on wheels to function, it is important to understand the value and types of wheels available to select the best product for your inventory needs. 

 

Push-Back Wheel Types & Features

Push-back systems vary from manufacturer to manufacturer. The primary function is the same, but the cart construction, wheels, and rails often have proprietary features. In general, when it comes to push-back wheels, you are looking for: 

Types of Push-Back Wheels Flat Tapered Flanged Contoured

Push-Back Wheel Features Low-friction Clean rolling Heavy-duty Quality bearings

Stainless steel wheels are most common in push-back racking. As part of a rack system responsible for carrying and storing heavy loads, the push-back wheels must be durable and function with little maintenance. The wheels are pre-lubricated when they arrive for installation and are often pre-installed on the individual carts. It is best to have bearings that are self-contained to keep out dirt and debris.

Wheels can either sit straight (flush) against the rail or are positioned at a slight angle. Additionally, the wheel shape can vary from flat, tapered, flanged, or contoured. How the wheel sits on the rail affects the amount of friction during flow. The ultimate goal of the push-back cart and wheel design is to reduce friction.

Wheel Design

• Flat –The full surface of a flat wheel fits flush against the rail, creating less friction and requiring less force to turn. As a result, the cart flows more freely, which reduces wear and tear on the forklift.
• Tapered – A tapered wheel has rounded sides intended to create less friction as it rolls. However, the inside and outside of the tapered wheel roll at different speeds, and the angle of force is not perpendicular to the axle, which can cause a tapered wheel to create more friction than a flat wheel.
• Flanged – Wheels with a flanged edge sit inside channel rails as opposed to flowing on top. The flange design helps guide the wheel along the rail to keep it in position.
• Contoured – Contoured wheels have a groove in the center so that the wheel essentially hugs the rail as it flows. 

 

Push-Back Wheel Maintenance

Push-back wheels and carts usually require minimal maintenance on only regular rack safety inspections. The wheels are pre-lubricated and expected to be long-lasting even in busy warehouse environments.  Systems should remain free from contact with ice, lubricants, or liquids that can impede cart flow and possibly cause pallet shifting. Inspect the push-back system during routine rack evaluations to ensure safe, efficient operation.

Routine maintenance should include:

• Check rails and carts for debris, clean with a brush if necessary.
• Look for rail damage, i.e., bumps or dips that can hinder flow. Replace if damaged.
• Check that rails are securely fastened.
• Look at the gap between the rails to ensure it is consistent down the entirety of the lane.
• Check for missing wheels and cart stability.
• Look for any cart defects or damage.
• Always look for loose anchors, missing or loose hardware, and broken welds.
• Depending on environmental conditions (e.g., extremely dirty or humid locations), periodic lubrication with WD-40 or a similar product may be necessary.  Grease or oil are not recommended.

Push-Back Cautions – Moisture & More

Push-back works most effectively in ambient and cooler/refrigerated storage facilities. However, they are less dependable in cooler and freezer environments where ice, lubricants, or liquids, can impede flow and increase the likelihood of pallets shifting and hanging up in the lane. 

All pallets in the lane should be the same weight. However, pallet weight variance can cause heavier pallets to push lighter pallets from the lane. An exception to this rule is 2-deep push-back lanes popular in case pick operations. In those situations, lower-level positions are set up to handle slight pallet weight variations.

 

Proper Pallet Loading & Unloading Steps for Push-Back Rack

Part of rack maintenance is preventing rack damage in the first place, so training your forklift operators on the unique features and loading/unloading techniques of the system goes a long way to minimizing repair costs and downtime. Go to our blog on push-back operator training for a thorough review of operator training. The basic steps are as follows:

Push-Back Rack Loading Steps:

• Lift pallet load approx 3”- 4” above the top cart. Be sure to clear pallet stops at the front when placing load onto the cart.
• Enter the rack and place the pallet centered onto the top cart, slowly back out of the system.
• To load subsequent pallets, line up the bottom boards of the 2nd pallet with the bottom boards of the first, just above the cart.
• Gently push back the 1st pallet as you enter the rack. Be sure to center the pallet over the exposed cart.
• Place the pallet on the cart and again back slowly out.
• Repeat the process until the lane is full. The last pallet in the lane will sit directly on the push-back rails.

Note: Forklift operators risk misloading subsequent pallets if a pallet is not sitting centered on the cart. Correct the misaligned pallet by purging the system, i.e., pick up the pallet, back out, then reload.

Push-Back Rack Unloading Steps:

• Center the forklift with the front pallet and slowly enter the lane.
• Lift the pallet 3”-4” to clear all pallet stops or obstructions.
• Slowly back out of the system while extracting the pallet. Rear carts will automatically glide forward to the aisle face.
• Repeat these steps until the lane is clear.

Special Considerations for Proper System Loading & Unloading

• Don’t rely solely on bumper plates to ensure a low-impact stop. Instead, the operator should control the cart flow by maintaining a slow backup speed. 
• The forklift operator should never touch the carts, rails, or rack face with the forklift forks.
• Occasionally, carts may need help getting restarted to flow forward. In those cases, the operator can purge the system by simply replacing the front pallet onto the top cart and gently pushing back about 2”-3” before slowly backing out again. After that, the stuck carts should regain momentum and flow forward. If carts do not begin on their own, debris or broken components could be stopping the flow. Inspect and repair the lane if needed.
• Avoid loading palletized inventory that can become snagged or hitched to the adjacent pallets in the lane. This can cause a dangerous situation when extracting pallets at the pick aisle.

For a deeper dive into push-back cart design and maintenance, take a look at our blog: Get on the Right Track with Push-Back Carts, Wheels & Tracks.

Keep Rolling with Apex Full-Service Support

The Apex team provides turn-key service for all your storage racking system needs, from standard to dynamic solutions and complex pick modules. We will evaluate your inventory needs and space opportunities to configure the best solution to equip your team for success. You just one call, you have access to systems experts, automation experts, vehicle and equipment experts, professional installers, and certified rack inspectors. One call does it all when you’re looking for custom warehouse solutions. So let’s get started today.