Refrigerated and frozen warehouses present a number of challenges beyond those present in ambient-temperature warehouses. The harsh temperatures can wreak havoc on the life span and functionality of lift trucks and their components, which translates to additional maintenance and repair costs, as well as the potential for significant downtime for cold storage facilities. With an eye to engineering exceptional performance, manufacturers offer lift trucks with cold storage options for optimal electronic, mechanical, and hydraulic performance.
We checked in with several major manufacturers of lift trucks for these unique environments to discover what to look for to optimize functionality while watching that bottom line.
Electric lift trucks are commonly used in these harsh applications. To take advantage of the pricey square footage due to the energy required to operate and maintain them, cold storage facilities are typically high-density, high-lift operations requiring the use of high-lift reach trucks and deep-reach trucks. “Manufacturers aim to design in as much protection as possible because of the electrical circuits that need to be protected against these harsh temperature conditions,” explains Jeff Bowles, manager of product marketing for Houston-based Mitsubishi Caterpillar Forklift America. “It’s not when you are in the freezer that the truck is most prone to the elements—
it’s more about what happens to the truck when it comes out of the freezer.”
What happens is condensation—the nemesis of any truck operating in these environments. “The number-one issue facing trucks when they leave the freezer is when they begin to sweat, which tracks into pins in the wiring harness,” reports Lou Micheletto, manager of warehouse product strategy for Yale Material Handling Corp. in Greenville, NC. About three years ago, the company began using a double-sealed connector design to minimize any invasion of moisture into the pin environment.
“We discovered that what was happening with some of the older and less expensive connectors was water would invade the area and then freeze when the truck re-entered the freezer, causing the area to expand,” Micheletto explains. “Upon defrosting again, the pin would be in a hole that was too big to make contact, resulting in a bad connection.” To eliminate the need for end-users having to change connectors frequently, Yale designed a high-end, double-sealed connector. Attacking the problem at its root cause eliminated the potential of condensation tracking into the pin area.
Another root-cause approach involved minimizing the number of wires in the harness assembly. “Historically, lift trucks have been controlled by a point-to-point set of wires running from the power source to the object being powered,” explains Micheletto. Reducing the amount of wires and the number of connectors, Yale minimized the likelihood of potential problems.
Yale engineers discovered that each truck model has its own signature condensation path. “We coated trucks with blue chalk to study how condensation follows specific pathways,” Micheletto reports. “The result was that we position all of our electronics, connectors, and wiring in areas located away from these pathways.”
Equipment life can deteriorate a lot quicker in these harsh environments than equipment operating in typical ambient applications, says Cesar Jimenz, national product planning manager for Toyota Material Handling USA in Irvine, CA. “Our customers are looking for products that last so they can maximize their ROI. We offer several environmental conditioning options, such as our freezer, cold storage, and rust-proof specifications to help protect critical areas of the lift truck in these environments.”
Attention To Details
Paying attention to the state of your trucks’ components can go a long way to extending the life and performance of your fleet. Understand the best oils and greases your trucks require for optimal performance in these harsh environments. Tend to your switches and other electrical devices and choose tires and batteries with deliberation, advise the experts.
Cold temperatures deplete the amount of usable energy from batteries operating the trucks, reports Jimenz at Toyota. “It has been documented that the battery’s capacity in a cold-store environment could be as low as 65 percent of that available at normal ambient temperatures. So in a typical 1000-amp battery, you really have only about 650 amps of energy available. This dramatically reduces run time, leading to lower levels of productivity and requiring either the use of a fast-charge system or more frequent battery changes to get through the work day.”
Recognizing this, Toyota improved the efficiencies of its controllers, drive motors, and lift motors so the energy required by these components lessen their impact on the truck’s energy requirements overall. “We use AC motors and controllers which utilize fewer moving parts, resulting in reduced component heat buildup and improved energy efficiencies,” explains Jimenz. Last year the company introduced its latest-generation four-wheel electric featuring Toyota’s most energy-efficient AC-powered system to date.
The choice of greases and oils is critical to the performance of your trucks, notes Micheletto. “Confirm what type of oil and grease your application requires and understand what their temperature ranges are before their viscosity thickens or thins. Remember that the most expensive oil is often the cheapest in the long run simply because it will do the best job.”
Switches and other electronic devices are also at risk when exposed to cold temperatures. “They can condense on the inside and to prevent that from happening, we introduce various forms of heat to evaporate the moisture,” Micheletto says. “It’s not that it’s bad for them to get wet. The problem arises when you go back into a freezer where switches can freeze closed. By keeping the switches heated, we minimize the risk of any issues developing, extending the life of the switch so the truck will run longer.” This is done using resistance heating, indirect heating to a specific area, or truck-generated heat that is channeled to the required components.
Choosing the right tires for your application is also critical, as freezer and cooler areas are ripe for traction problems. “Many electric lift trucks in these environments are equipped with polyurethane tires rather than rubber tires,” reports Bowles at Mitsubishi Caterpillar. “It’s important to consider a poly-traction tire that is siped, treaded, or even sanded. For instance, we offer a 4,500-pound walkie—popular in the produce industry—that uses an optional rubber or sanded poly drive tire for those cold and wet conditions. A lack of traction can accelerate tire wear and this becomes a maintenance cost over the life of the truck.”
There’s no doubt about it—these environments can become very slippery as trucks sweat, increasing the potential for tip-overs. Toyota offers its System of Active Stability on its sit-down counter-balanced trucks to compensate for these situations. “When the system senses instability, it engages a swing lock cylinder to stabilize the rear axle to help keep all four tires on the ground.”
Driver comfort and safety is high on the list of priorities in choosing the right truck. Because operators must work with heavy and bulky freezer suits, manufacturers are sensitive to providing a user-friendly work area. “We design our equipment so operators are as comfortable as possible when they are working,” says Susan Comfort, product manager, narrow aisle products at The Raymond Corp. in Greene, NY. “Handles and floor mats are heated for their comfort.”
Yale provides the maximum amount of adjustability in its steer tillers, reports Micheletto. “Operators can easily change the position of the steering wheel so that it doesn’t rub against their bodies as they work. Our function controls—such as the handles—are ergonomically designed and engineered so operators can control them even when they are wearing heavy mittens or gloves.”
Maintenance For Performance, Safety
It’s critical to conduct periodic inspections on equipment used in these harsh environments and most manufacturers suggest that end users conduct inspections every 250 hours to 500 hours. “We at Raymond recommend that you adhere to the OEM’s suggested scheduled maintenance,” says Comfort. “Make sure everything is properly greased. Housekeeping is also very important to consider in keeping maintenance costs under control. For instance, pick up loose pallet debris so it doesn’t damage tires, which can lead to premature tire damage.”
End users are also looking for ways to reduce accidental impacts that can damage equipment as well as products. “Raymond has an impact sensor—as part of our iWarehouse fleet management system—that alerts the warehouse manager when an operator has impacted something,” reports Comfort. “It is a training aid that helps operators be more careful and accountable in their work. It helps reduce the cost of maintaining equipment and it acts as a tool to let managers know which operators might need additional training. One customer of ours reduced the incidence of impacts by 88 percent within just five months after implementing our product, iImpact.”