When a lift truck falls off a dock, overturns or simply runs out of juice in the middle of a critical pick, it’s a black eye (or worse) for both operations and maintenance. But the costs of such high-profile events may pale in comparison to everyday waste due to breakdowns, damage to equipment, product and the facility, and repetitive injuries.
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“Maintenance is always coming to me saying operators are tearing up their equipment,” says Annette McDaniels, instructor of safety at Toyota Forklifts of Atlanta (www.atlantaforklifts.com).
“They don’t realize how operator safety can reduce maintenance costs.” At a facility where operators are trained once per year, “We see zero incidents and no unplanned downtime,” McDaniels says. “At another plant where we just recently became involved, the managements has, how shall I say it, a ‘let’s go’ attitude, and they have incredible downtime.”
Training remains key to safe, productive operations, but lift truck technology, ergonomics and dock equipment have come a long way in the past few years.
This side up
Lift truck manufacturers have drawn on the latest sensor, microprocessor and servo technologies to build in life- and property-saving features. While not available (or needed) for every application, a quick tour tells a lot about lift truck dynamics.
Trained operators know not to transport elevated loads, but some raised motion is inevitable when picking and placing. Electronic controls can limit truck speeds and mast angles based on current operating conditions, and even lock rear suspension to improve stability when needed.
Some trucks limit speed according to turning radius. “CurveControl is a proactive system for lateral stability in cornering,” says Jason Dunigan, product manager, Jungheinrich (www.jungheinrich.com). “It controls the speed according to the turning radius – as the wheel angle increases, the truck automatically slows. It’s done electronically through the programmable controller on the unit.”
Toyota offers two patented systems: System of Active Stability (SAS) and Active Mast Control (AMC). Starting in 1999, the systems have been integrated into all the company’s internal combustion and electric sit-down counterbalanced models. “Operator safety training remains the first line of defense in reducing forklift related incidents,” says Martin Boyd, national product planning manager, Toyota Material Handling, U.S.A. (www.toyotaforklift.com). “However, it is known all too well in the lift truck industry that errors in operator judgment, as minimal as they may seem, often lead to accidents. Toyota’s SAS and AMC technologies were designed specifically to reduce the likelihood of accidents during these ‘errors in judgment’ scenarios.”
SAS (Figure 1) senses mast height, load weight, vehicle speed and yaw rate (angular acceleration); conditions that play a significant role in lateral lift truck stability. “Should the operator mistakenly place the lift truck in an unsafe condition which may lead to potential lateral overturn, SAS instantly interprets those conditions and locks a hydraulic cylinder on the rear steer axle, changing the lift truck’s stability footprint from triangular in shape to rectangular, thereby increasing lateral stability and substantially reducing the likelihood of a lateral overturn,” Boyd says.
AMC, which is standard equipment on the company’s three-wheel electric models and an integral part of SAS on the four-wheel sit-down IC and electric models, senses mast height and load; conditions that play a significant role in longitudinal stability. A forward tilt angle controller automatically overrides the operator’s manual control, and limits forward tilt to decrease the likelihood of a forward tip-over or spilled load. A rear tilt speed control automatically governs the mast’s reverse tilt speed to reduce the likelihood of a rearward tip-over or spilled load.
Sophisticated electronics also support more pedestrian features, such as operator-specific speed and acceleration limits, collision detection and safety-related convenience features. “The controller determines the maximum acceleration rate and top speed, and can be set up to limit them differently for the individual driver codes the operators use to log onto the machine,” says Dunigan.
Operators know the truck is tracking who’s driving it and if it has hit something, so they tend to be more careful.
Controllers, variable-speed drives and AC motors allow precise maneuvers and automatic safety features. For example, a “snail” button on Jungheinrich trucks engages a creep mode for controlled maneuvers in tight places. The parking brake is automatically set when the operator leaves the machine, and also on inclines – you can take your foot off the brake and it will stay put. Speed is controlled on downhill inclines, Dunigan says, “If you take your foot off the gas, it won’t speed up.”
Lift trucks are durable equipment with high initial costs and long service lives, so much of the existing fleet doesn’t have the latest safety features, but most trucks have or can be fitted with basics like governors and operator interlocks. For many applications, those appear to satisfy users.
“We buy our trucks refurbished and they don’t have stability control,” says Doug Jones, facilities manager, Yarde Metals, Southington, Conn. “Ours are fitted with standard safety gear and governed at 7 mph maximum speed. We’re experimenting with a device that stops the truck -- if an operator hits something, he has to go get a supervisor with a key to turn it back on.”
The technologies that support controllability and stability also can ease maintenance and troubleshooting, and improve energy efficiency. “The electronic controller improves reliability and serviceability as well as safety,” says Dunigan. “If it detects a malfunction it will light a warning or stop the truck, depending on the nature of the problem, and you can read out the diagnostics with a laptop.”
Microprocessor controls can detect and protect low batteries. “When the battery charge drops to 20%, the lift function stops working,” Dunigan says, “leaving you enough capacity to get back to the charger without depleting and damaging the battery.”
AC drives make regenerative braking practical, and some trucks also can capture lift energy during load descent. The result is longer battery life between charges or changes, and, Dunigan says, “People do sometimes get hurt changing batteries.”
The right equipment can minimize and ease routine maintenance, saving time and ensuring it gets done, and done right. Consider automatic battery watering systems. “They’re a little pricey, but they save time,” says Bob Carpenter, operations manager at American Granby, Syracuse, N.Y. His 100,000 sq.ft. pick/pack/ship facility has three narrow-aisle Raymond 5000 Series order-picker machines and two Raymond Model 7400 reach trucks. “With the automatic systems, battery watering takes 15 seconds versus 10 to 30 minutes -- it takes 10, but they use 30,” Carpenter says.
“When you have a number of trucks, that adds up.” At American Granby, watering all the trucks “takes 10 minutes instead of three hours,” he says, “and the batteries actually get watered.”
But whether your trucks sport the latest self-monitoring systems and automatic equipment, or pre-date the Second World War, the single most effective way to simultaneously reduce maintenance costs and foster safety is the pre-shift inspection. “A lift truck is an expensive asset,” says Bob Mundson, operator safety training manager, Mitsubishi Caterpillar Forklift America (MCFA, www.mcfa.com). “It’s costly to replace or repair. Pre-shift inspections can hold down costs.”
The pre-shift or pre-operational inspection is a visual and functional inspection of the truck to see if there’s anything wrong. Typical checklist examples and versions for specific models are readily available from the Web, lift truck manufacturers, local dealers or as part of operator training packages. “It takes a few minutes,” Mundson says. “Check the horns, alarms, lights, oil or fuel leaks, hydraulics, traction and steering work properly. It’s required by OSHA, but not all plants do it.”
Trainer McDaniels says she’s “amazed at how many people who get on a lift truck know nothing about it – where the air filter is, how the hydraulics work or even how to take care of the battery. So they get short battery life, and those things aren’t cheap.”
Comprehensive operator training will include pre-shift inspections. “Operators learn to catch problems early, before they become major,” says McDaniels. “They’ll see a hydraulic leak before it becomes a damaged pump.” They also learn more about the critical connection between truck condition and safety. “If the truck’s not operational, tag it out and send it to maintenance,” he says.
“We can’t stress this enough — it’s a powerful machine that can cause a lot of damage.”
People are constantly rediscovering how to be maimed or killed in connection with lift trucks, but a more insidious cause of non-productivity is ergonomics. Shock and vibration from uneven traveling surfaces can slow productivity, damage loads and make operators tired, numb and sore.
Obstructed sightlines and poorly designed or maintained operator contact surfaces and controls can reduce safety and increase fatigue.
Studies reported in the Journal of Biomedical Engineering conclude that operator comfort provides quantifiable business benefits in higher productivity, improved worker health and energy levels, reduced absenteeism and increased job satisfaction. Truck manufacturers have seized on ergonomics as a way to add value and distinguish their offerings.
Users say they can feel the difference. When American Granby recently moved to a new facility with taller racks, “Going from 16-ft. to 30-ft. ceiling height had us worried about safety,” says Mary Lanzafame, American Granby vice president of operations. They decided to compare four brands of order-pickers.
“We had our two best operators run them and test them,” says Carpenter. “They felt safer on the Raymonds because they are more solid – less swaying, less vibration and rattling. They also run quieter and smoother, which means fewer dropped boxes.”
The operators noticed differences such as cushioned platforms and responsive deadman switches.
“You don’t have to stomp on them, and when you have to operate a truck for three hours straight, that can help avoid a leg cramp,” says Carpenter. “Our trucks are wire-guided, and these trucks have a hand rest – a grab handle – to hold onto when you’re on the wire and not driving. On the others, you end up hanging onto the wire grate.” On some trucks, he says, the front controls protrude about six inches onto the platform, leaving less room to stand. “Our operators felt the difference.”
Many ergonomics have strong safety implications. For example, some machines offer better sightlines so operators don’t have to strain to see, which also might help them avoid a collision with another truck or a pedestrian (Figure 2). A well-placed horn button can be pressed without taking your eyes off the aisle, and also is more likely to be used at every intersection.
Dual controls let operators face forward when driving in either direction, relieving a major source of twisting and neck strain, but also enhancing visibility and control. “Our Universal Stance reach-fork truck provides an example of how good ergonomic design improves operator comfort and performance,” says Kevin Trenga, manager, marketing communications, The Raymond Corp. (www.raymondcorp.com). Reach trucks are designed for right-angle stacking pallets in racks.
“Universal Stance allows operators to operate the lift truck with their heads and shoulders facing squarely in the direction of the task to be performed,” he says. “The driver…is able to work in the racks and still maintain a view of activity up and down the aisles with no more than a look 90° left and right from ergonomic neutral.”
Put it on the dock
Safe truck operations also depend on the operating environment, and few things can ruin a day on the dock like an unscheduled tractor-trailer departure. J&J Snack Foods’ Pennsauken, N.J. warehouse uses a system from Salvo (www.salvousa.com) that puts a lock on the trailer brakes and interlocks them with the dock door so the trailer can’t be pulled out unless the door is closed.
“We’d had several near misses,” says Phil Heffelinger, J&J director of engineering, “and wanted to find a product that offered a high level of reliability and low maintenance.”
Each lock is coded for a specific door, so the system prevents drivers from backing into the wrong door and being loaded. It also can reduce energy costs from open dock doors. “Previously, our dock attendants would sometimes prematurely open a door while they waited for the driver to properly spot the trailer,” says Heffelfinger. “Salvo will save us a lot of money on refrigeration costs, and since some of the trailers are spotted or dropped at a door, Salvo also protects the trailer from being stolen.”
Even when the trailer stays put, lift trucks and standup walkies often are jarred and jolted as they transfer materials within a facility’s shipping/receiving/staging area and move in and out of semi-trailer trucks.
“For decades, companies have viewed lift truck jarring and jolting as something they had to live with,” says Kyle Nelson, vice president, new business and product development, Rite-Hite (www.ritehite.com). “But there is growing concern worldwide about lift truck operator safety and the need to avoid chronic spinal-related injuries caused by vibration. Additionally, companies are always looking for ways to make their dock a more productive and profitable working environment.”
Rite-Hite’s research and analyses showed jarring occurs when a lift truck crosses between the warehouse floor and the trailer bed due to the bumps and gaps that exist on traditional dock levelers. The trailer beds also move vertically due to the weight of lift trucks traveling in and out of unstable trailers. The problem can be severe on trailers with air-ride suspension systems.
The company designed modifications to its leveler design to minimize the jarring at key transition points, and improved the design of its vehicle restraints, resulting in what it calls the Smooth Transition Dok System.
Results of leveler tests using the ISO2631/1 standard were measured against Directive 2002/44/EC of the European Parliament and Council of the European Union, which is the most stringent guideline available for vibration exposure in the workplace. The testing showed that the new levelers reduce dock shock by 50% compared with standard levelers under the same conditions.
Tests using a linear velocity displacement transducer showed the redesigned vehicle restraint can reduce trailer drop by as much as 300% versus standard versions under the same conditions.
Along with less wear and tear on the operator and potential shock damage to loads and lift trucks, smoother transitions mean operators can enter and leave trailers with less severe braking, which can reduce brake wear, increase battery charge intervals and increase productivity.
Safety should always be a plant’s number-one priority, but often it’s perceived as coming with higher maintenance and lower output. With lift trucks, attention to safety is not only likely to save a life – it can improve operator comfort, reduce product and infrastructure damage, lower lift truck life-cycle costs and raise productivity of lift truck operations.
Figures: Jungheinrich, Toyota
What went wrong?
True examples of lift truck accidents show many ways operators, equipment and environment too often interact with deadly results. Here are a few headlines of incident reports at www.cdc.gov/niosh/injury/traumamcface.html#inmanufacturing:
- Welder dies in fall from fork lift
- Order selector dies after jumping 16 ft. from an elevated pallet on an overturning forklift
- Forklift operator dies after being caught between mast and cage of forklift
- Loading dock worker crushed between forklift and flatbed truck
- Warehouse checker crushed under a 4,000-pound crate falling from a forklift
- Operator crushed to death between forklift truck cage and metal beam
- Worker electrocuted when boom forklift contacted power lines
- Forklift crushes operator working underneath on starter
- Warehouse forklift operator crushed against rack beam
- Standup forklift operator asphyxiated by warning chain
- Company president killed when forklift overturns
The Pre-Operational Inspection
The importance to you is to:
- Reduce the risk of injury to you due to defective equipment.
- Verify that the equipment you will operate is in safe working order.
Federal OSHA requires that all lift trucks be examined before being placed in service and that this examination be performed at least daily. If you use your truck on a multi-shift operation, it must be examined before each shift. Any defects found must be immediately reported and corrected.
About 6% of all lift truck accidents are due to improperly maintained trucks.
Aside from being an OSHA requirement, a pre-operational inspection:
- Reduces the risk of injury to you and other employees.
- Improves the condition of the lift truck.
- Increase productivity.
- Reduces downtime and maintenance costs.
Use a checklist when performing the pre-operational inspection. A checklist may include the following cautions and checkpoints:
CAUTION: When checking lift chain tension, use a board or a stick. Never place your fingers in this dangerous pinch point area.
CAUTION: When checking hydraulic hoses, use a piece of cardboard. Escaping fluids under pressure can penetrate body tissue causing serious injury or possibly death. If fluid is injected in your skin, seek medical attention immediately.
CAUTION: When checking LP tanks and fittings, always use personal protective equipment such as a face shield, long sleeves and gauntlet gloves when checking LP tanks and fittings. LP is very cold when released and can cause frostbite.
CAUTION: When checking LP tanks and fittings for leaks, use soap solution, no matches or lighter.
CAUTION: When checking battery levels, never use matches or a lighter – hydrogen gas may be present, resulting in an explosion or fire. Always use personal protective equipment such as a face shield and goggles, rubber apron and rubber gloves when checking electrolyte. This is an acid and will cause severe burns to the skin if in contact.
The Visual Inspection
__ Overall condition
__ Tires and wheels
__ Mast, carriage and load backrest extension
__ Lift chains
__ Hydraulic hoses
__ Overhead guard
__ Cables and connectors
__ Battery restraints
__ Electrolyte level
__ Hood latch
__ Capacity plate and all warning decals
__ Operator’s compartment
Internal Combustion Trucks
__ Engine compartment
__ Engine oil
__ Brake reservoir
__ Engine coolant
__ Air filter
__ Belts and hoses
__ Hood latch
__ Properly mounted tank
__ Pressure relief valve pointing up
__ Hose and connections
__ Tank restraint brackets
__ Tank for dents, nicks, cracks
__ Tank fits within profile of truck
__ Cables and connectors for frayed, exposed wires
__ Battery restraints in place
__ Electrolyte levels
__ Hood latches properly
The Operational Inspection
__ Operator restraint system
__ Warning devices
__ Unusual engine noise
__ Fuel level
__ Displays and gauges
__ Other hydraulic functions
__ Service and park brake
__ Plugging on electric lift trucks
Completion of Inspection
- Report any defects immediately.
- Never operate a truck in need of repair.
- Repairs shall be made by authorized and trained personnel.