As high-density storage gains popularity, more facilities are using high-lift forklifts, like order pickers, turret trucks, and reach trucks. This specialized equipment comes with its own set of safety considerations.
Reach for the sky ... No, we're not talking about gunslingers in the Wild West. Instead, that could be the new mantra for warehouse and distribution center operators as they seek to maximize storage space by using high-bay facilities with narrow aisles and racks that seem to get taller by the year.
Lift truck manufacturers have designed electric-powered equipment specifically for this high-density, often narrow-aisle and very narrow-aisle, environment. Examples include reach and stacker trucks, which keep the operator on the ground while the forks and mast rise to the required height for pallet putaway and retrieval, and order pickers and turret trucks, which lift the operator in a compartment or on a platform into the racks for case or piece picking.
How high can they go? That varies greatly depending on the type of truck and the application, but the manufacturers we spoke with offer equipment with a total of 18 different mast heights, ranging from 17.5 feet to 59 feet. Several manufacturers said that customers are asking to go still higher.
Because these lift trucks perform their work at such great heights, there are a number of safety considerations associated with this type of equipment. Here's a quick overview.
STABILITY IS NUMBER ONE
The American National Standards Institute (ANSI) safety standard B56.1-2012, administered by the Industrial Truck Standards Development Foundation (ITSDF), applies to high-lift trucks. It covers everything from fall protection and braking requirements to compliance testing and maintenance. The standard is not just for equipment manufacturers, though; it also defines safety requirements for users and has been adopted by the Occupational Safety and Health Administration (OSHA). (The B56 standards for all types of lift trucks are available at no charge at www.itsdf.org/pB56.asp.)
With high-reach trucks, stability is the critical safety issue. Four main factors come into play here. The first is the vehicle's legs, known as outriggers. With a standard sit-down counterbalanced truck, the higher you go, the less weight you can lift because the truck's center of gravity shifts forward as the load ascends, says Tony Kordes, product manager at UniCarriers. But high-reach trucks generally can carry more consistent weights regardless of height because "they straddle the load with outriggers, so the center of gravity is close to the mast," he says. Higher lifts call for wider outriggers, which also have to absorb lateral loads to prevent tipping as the truck leans left or right, Kordes adds.
The second element is the mast. As it rises by means of a series of stages, or sliding extensions, it becomes subject to twisting, swaying (particularly when the operator moves around), side bowing, and leaning forward ("deflection"). "This means the mast should be rigid enough to minimize sway and have the ability to evenly distribute load forces throughout the frame," says Matt Barrow, product manager for Yale Materials Handling Corp. How effectively a mast does that varies with the manufacturer, the mast design, and the type of truck, but strong torsional rigidity is a must.
Some manufacturers have software that helps to keep the mast steady. Cat Lift Trucks, for example, says the Active Sway Control feature available on certain models of its reach trucks uses software to calculate mast sway; it then provides a compensating movement to control acceleration and braking so that the driver's compartment remains stable at all heights.
The third stability factor is the flatness of the floor. "Super-flat floors are required for turret and swing reach trucks because neither their masts nor their carriages tilt to help them compensate for the irregularities of common warehouse floors," says Bruce Dickey, vice president of sales for Narrow Aisle Inc. "This requirement can add significant cost to turret and swing reach truck installations," he notes, adding that flatness requirements for the articulating narrow- and very-narrow-aisle trucks his company provides are much less stringent.
Last is the weight of the battery, says Susan Comfort, product manager, narrow-aisle products, for The Raymond Corp. "The battery needs to be bigger because it has to function as a counterweight for the height. But there's a trade-off: The bigger battery may mean a wider truck, which may limit the width of the aisles where the truck can work," she says.
Because the tall mast may be called on to lift and lower loads (and in certain types of trucks, the operator, too) while the truck is moving, speed must be strictly controlled if stability is to be maintained. As the operator and/or load goes higher, the truck's operating software will automatically reduce the vehicle's speed, says Scott Carlin, electric product support manager at Toyota Material Handling U.S.A.
LOOK OUT BELOW
With order pickers and turret trucks, which elevate the operator, users have a restricted view of what's going on below them, notes Perry Ardito, general manager, warehouse products group North America for Jungheinrich. For that reason, more buyers are investing in warning systems that can detect obstructions, people, and objects in the truck's path. One solution offered by Jungheinrich and some others, particularly in Europe, is a laser system that detects obstructions in front of and behind the truck and will automatically slow or stop the vehicle before it makes contact. Most operator-up trucks have strobe or other warning lights below the platform. Safety cameras and 360-degree lasers are on the drawing board, and some manufacturers offer features that automatically slow or halt the truck at the ends of aisles.
High-lift trucks often have a vertical load backrest to help prevent items from falling off the forks and tumbling onto the operator's platform or to the floor far below. They're also required to have overhead guards to protect operators from falling objects, but these are not designed to protect against very heavy items.
Overhead guards also protect the operator if they bump into obstructions on the ceilings. The latter is a more common problem than you might think. "At 440 inches, you are close to the ceiling, where you may run into lights, heating ducts, and sprinklers," says UniCarriers' Kordes. "Some companies plan for ceiling clearance of the racks, but they don't take into account the load height when a truck takes it off the top rack. They forget that they need four to six additional inches for lifting the load." This can easily be prevented if the truck can be programmed not to lift above a specified height.
A facility design and layout that are not uniform throughout the building can present a safety hazard for high-lift trucks, says Tim Forlow, senior product marketing manager for Crown Equipment Corp. If a roof is graded or has even a slight slope, you'll need to account for the lowest positions of lighting, ducts, and other ceiling-mounted obstructions. Furthermore, tall equipment may work well in one section of a warehouse, but not in another, he says. "People forget that the other section of the warehouse may have different measurements. You have to know what is the collapse height of the truck and make sure the truck can go underneath doors between sections of a DC or tunnels built into rack."
Operator falls are an even bigger worry than falling cases or bumped heads. The ANSI/ITSDF standards and OSHA regulations specify what kind of fall protection is acceptable. For most trucks, the regulations allow a body belt with a self-retracting lanyard, a full-body harness with an energy-absorbing lanyard (maximum six feet in length), or a full-body harness with a self-retracting lanyard. (On its website, OSHA says it "strongly encourages" the use of body harnesses on elevated platforms of all types of powered industrial trucks.) Since 2013, the specifications have been based on the operator's weight, with different requirements for operators weighing less than 220 pounds, from 220 to 310 pounds, and from 311 to 400 pounds. If an operator weighs more than 220 pounds, the truck's capacity must be reduced by an amount equivalent to the operator's weight in excess of 220 pounds.
The belts and harnesses are just one element of fall protection, though. The standards also specify what's permissible in terms of the height and strength of guardrails and cabins, including side gates (must withstand specified pressure), floor covering (non-slip), and pedals or other protuberances (nothing you could trip over).
Another concern is reducing the chances of sudden or inadvertent motion that could catch an operator by surprise and throw him or her off-balance. "To prevent the truck from moving unless activated by the operator," says Yale's Barrow, "man-up trucks can contain built-in interlock functions that will not allow truck operation without proper engagement, such as retractable side gates and floor pedals that cut out traction and hydraulic functions."
What if something goes wrong—say, an operator becomes ill or incapacitated while 30, 40, or 50 feet in the air? A "kill switch" on the control panel can be used to cut the power in an emergency. OSHA also requires that every operator-up truck have a mechanism that allows someone on the ground to slowly lower the operator's platform or cabin.
And if a fire breaks out in a facility with operator-up trucks? Right now, the National Fire Protection Association (NFPA), the standards organization that issues fire-prevention and protection regulations, has no protocol specifically for this situation, says Matt Klaus, principal fire protection engineer and the group's expert on sprinkler systems. These systems are designed to protect goods, equipment, and the building itself, as well as people on the ground. But "if, say, you have six-tiered racks, a sprinkler system isn't designed to suppress and control fire for a person that high up in the air," Klaus says. Because smoke rises, a facility may want to consider a smoke management system in conjunction with its sprinkler system, he suggests.
The inherent dangers of operating high-reach equipment have prompted many manufacturers to incorporate technology that enhances safety by taking some of the decision-making away from the operator, Jungheinrich's Ardito says. Some high-lift trucks incorporate software that controls things like direction and speed of travel, cornering speed, angle of steer, and lift height and speed. Jungheinrich's optional Warehouse Navigation System, for example, determines the optimal lift height for order pickers as they travel between picking locations, raising and lowering the operator's platform and the forks to achieve the greatest safety, speed, and efficiency. Another example: Narrow-aisle and very-narrow-aisle trucks may be guided by electromechanical wires embedded in the floor, so the operator doesn't have to steer. This prevents impacts with racks and reduces injuries and accidents; in wide aisles, it allows two trucks to work different sides of the same aisle without worry of collision. In smaller facilities, metal rails bolted to the floor offer similar benefits.
But while technology can go far in making high-lift trucks safer, it can only supplement human knowledge and decision-making. There is no substitute, says Cesar Jimenez, director, product planning, technical and warranty for Toyota Material Handling U.S.A., for a properly trained, experienced, and careful operator who understands the potential dangers of these trucks and will exercise good judgment when operating them.
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