Most distribution centers utilize rack modules in their operations in order to maximize storage space and operational efficiency. Rack modules can be designed in a wide variety of configurations depending on the applications. Often these configurations require space for workers to pick from the pallet drop areas throughout the rack structure, or to stack empty pallets and empty totes into open bays.
When workers are involved in operations on elevated work platforms and pick modules, it’s necessary to plan for safety and fall protection. There are a number of ways safety can be achieved, and industry standards like those issued by ANSI and OSHA require a dual-gate system. Safety advantages provided by dual-gate systems, like the models we offer, ensure that workers are safe at all times; when the ledge gate is open, the rear-side gate is closed, preventing the worker from access to the ledge. When the rear-side gate is open, the ledge-side gate closes, providing a safe, enclosed workstation while the bay is picked.
A dual-gate system also keeps the picker a safe distance from the lift truck loading a pallet, as a fixed barrier will be in place while the pallet is being pushed into the bay. This creates a physical barrier between the picker and a pallet being pushed into the area with the force of a lift truck.
A dual-gate safety system is now a standard in the industry, so the decision to install them to secure picking positions and empty pallet return bays is obvious. But the real decision is what type of dual-gate system. There are dual-gate pivot and Roly models, both of which will maintain a safe environment at all times; there are also rack-supported and free-standing gates.
A Pivot Gate has few moving parts and is often the most economical choice, but keep in mind that this design needs room for the gates to pivot, or arc, when operated. When the pivot gate is in use, the ledge-side gate extends out into the truck aisle, and the rear-side gate extends back into the picking aisle. This often is not an issue, but can be if the picking aisle is narrow, or if the lift truck is loading multiple levels.
A Roly Gate solves this issue as the design uses gates that open and close flush within the confines of the rack structure, so the ledge-side gate opens flush with the ledge, and the rear-side gate opens flush with the rear-side column.
Both of these designs are available in both free-standing and rack-supported configurations. When operations needs flexibility, and pallet drop areas frequently move locations within the facility, a freestanding safety gate model can be used efficiently within a rack module. The free-standing gate can be unbolted from the decking, moved to another location, then re-secured. We have seen this work well for some unique material handling operations, and with companies that require a flexible layout.
The other option is Rack-Supported safety gates. This style attaches directly to the existing rack uprights instead of being lagged down into the decking. The rack-supported model has three main advantages over a freestanding model: (1) space savings, (2) more secure connections and (3) cost savings. By utilizing the existing pallet racks for support, the rack-supported model takes up a minimum amount of space in the rack bay, gets tied into the entire rack system and uses few components.
You’ll also have to decide on the size of the safety gate. Because we’re talking about integrating with a rack-module, the existing bay size determines the width of the gate, but you’ll need to decide on the depth and the height that is required. The safety gate needs to be deep enough to accommodate the pallet without being so deep that it projects too far into the picking aisle. With a standard 48” deep pallet, the safety gate should provide a minimum of 56” in clearance to provide room to load the pallet into the area. Because most uprights are only 48” deep, often the safety gate will extend beyond the upright, either back into the picking aisle or into the lift-truck aisle with a platform extension. The safety gate should be made tall enough to accommodate the tallest pallet with some room factored in for fork truck lift-off space, and to allow pickers room to enter the bay to work the pallet, without being too tall that the raised gate is difficult to reach. Sometimes a beam may need to be removed to provide adequate height.
Many dual-gate systems that are both free-standing and rack-supported can be power operated with remote radio frequency controls. To learn more about whether or not to power operate a pallet drop gate, please see this blog post on the subject.
The decision to secure picking positions in a multi-level rack picking module should be an easy one. Where it gets complicated is deciding on which safety gate will best fit your application and how it should be sized and configured. This is where a professional in the industry should be consulted, either through a material handling consultant, distributor, or by reaching out to us.
One of the questions we get asked a lot is whether or not to power operate a pallet drop gate. For most applications, we recommend skipping the power option. Manual operation creates the highest level of safety because the operator on the platform, who we are trying to protect, is the only person controlling the opening and closing of the gate. This can be very important for any material handling or manufacturing application.
The majority of the end users inquiring about power operation believe that operations will be slowed unless the fork lift operator can open the safety gate. The concern is that the lift truck operator will go to load a pallet and the gate will be closed. This would cause the operator to get off the truck, climb up the stairs to the mezzanine level, open the gate go back down below to the lift truck to finish loading the pallet.
We agree that this is an issue when using a single-gate system like a sliding gate or a swinging gate. For that type of design, in order ensure safety in the area the gate has to be closed; and in order to load a pallet the gate has to be open.
However, this is not the case when using a dual-gate system, which is the type of guarding that all pallet drop areas on elevated work platforms should use according to ANSI MH-28.3. When using a dual-gate system, the area can always be safe because the employees working in the pallet drop area can close the rear/operator gate when they are done removing the material to ensure the area is always ready to receive a pallet because the ledge-side gate opens when the rear-side gate closes. As long as the gate is left in this position the area is always ready to receive a pallet so there is no reason to give control to lift truck operators down below.
How to make sure employees close the rear-side gate is a concern of customers who understand the issue with power-operation from below. We have found over the years that this issue gets resolved by communication and training among the operators. More often than not, the position of the gate becomes a signal so when the picking on the mezzanine is ready for the area to be replenished, he/she will toggle the gate, closing the rear-side gate, which opens the ledge side gate. Now the lift truck operator looks up and sees the ledge-side gate open and knows it is time for the area to be replenished.
Sometimes we get asked to power operate the gate because the operator on the lift truck is the same operator that goes up on the elevated work platform. But, this scenario is ideal for manual operation because the operator must leave the ledge-side gate open when they go down to the lower level, because if they do not, they will have to go back up to the mezzanine to reverse the position of the dual-gate system. After making that mistake once, they’ll likely remember to always leave the ledge-side gate open for the next time they’ll be loading.
Of course every application is different, and everyone’s operation is different, which is why we do offer the option to purchase our safety gates with power operation. All of those power-operated systems include built-in safety features like photo eyes that detect the presence of a person or object and prevent the gates from closing, along with a clutch that will engage if the gate were to make contact with an object, which is adjustable so it can be set to the proper sensitivity for that specific environment. We also add power to gates that are involved in operations with AGVs.
The motors are all commercial operators will built-in safety features and numerous controls that can be used, like radio frequency remotes on the lift truck, and flashing lights and caution alarms. But we recommend caution on all of these remote operators, and always advise customers to test the unit in manual operation because they can always add the power option later, which by the way, we’ve never had a customer take that advice and then come back later to add power operation – they always stick with the manual operation. With proper training and education, the manual operation will create the safest environment, and shouldn’t slow down the operation.