Ergonomics: Equipment Design That Works

March 1, 2002

Manufacturers use the word ergonomics quite freely, and contractors have commented that it is just another one of those “highfalutin’ words the sales reps throw at us.” To designers, though, ergonomics means comfortable efficiency–an excellent goal. But we still might question how a change in control position, a style of handle, or extra room for our feet constitute practical improvements.

Professor Waldemar Karwowski, president of the International Ergonomics Association and a professor at the University of Louisville in Kentucky, put us in touch with Ian Noy, Ph.D., chief of the Ergonomics Division of Transport Canada, for an expert opinion on this subject. “Ergonomic improvements are possible only after a thorough analysis of the operator’s physical and cognitive tasks,” maintains Noy. “These may relate to the physical workstation, the design of controls and displays, or the work processes, et cetera. Often several aspects need to be considered concurrently since they may interact. Claims that a product is ergonomically designed need to be backed up by evidence that qualified ergonomists have contributed to the analysis, design, testing, and evaluation.”

Safety is most important at any work site, but there is more to engineering advances in construction equipment design than making everything safe to operate. Those improvements called ergonomic should be seen as ways to be more efficient and profitable too. A good seat, for example, does not only make the operator more comfortable; it makes him or her more productive. Controls close to hand and simple to operate not only prevent wrist and finger problems, they also make operation faster and more accurate. In recent years, ergonomics (which simply means “the laws of work”) has received more publicity for its role in offices, factories, and hospitals than it has in the construction sector–possibly because more people work in the former.

Construction workers and contractors have always been aware of the importance of ergonomics in their daily routines, even if they have not used that word specifically. When a loader operator says that a new model is simple to control and how he no longer feels like a pianist with short fingers playing arpeggios as he manipulates buttons and knobs, he is praising the machine’s ergonomics. When an excavator operator climbs out of the cab, saying he has no backache, no stiffness in the wrists, and no headache, he is pointing out that the ergonomic design of the excavator has both improved his own performance and prevented any harm to his physical condition. It is good ergonomics when the operator of a skid-steer loader emerges from the machine without feeling as if its vibrations are making him shake and shimmy as he walks about the site. Ergonomics makes work efficient and comfortable and ensures that the operator develops no short- or long-term disabilities from its use.

“We always strive to improve operator comfort and productivity,” says Erik Wilde, excavator product manager for Komatsu. “Properly placed controls can reduce cycle times and operator fatigue. After all, an excavator is only as productive as the operator running it.”

Perfect for Everybody?

Lower-back pain is the traditional complaint for excavator and loader operators, according to many contractors, and new seating systems have dramatically helped reduce that occupational hazard. Another example occurred a few years ago when Komatsu realized that more and more excavator operators in Japan are not men but women, so they produced cabs suited to the smaller size of a typical Japanese woman. One of the leading reasons why customers purchase Komatsu equipment is the company’s “People First” approach to design.

Many factors are involved in making a machine or a tool acceptable in an ergonomic sense. One of the most important considerations: “Is this machine user-friendly as far as my employees are concerned?” That “user-friendly” is a phrase used mostly with computer hardware and software, but an ergonomically engineered construction machine or tool must address the same issue: It ought to make operation simple and friendly. But is it really possible to make an excavator, for example, that is perfect for everyone? Is it possible to design a skid-steer loader that will suit every user’s physique? We doubt it, but many contractors tell us that a session in a skid-steer of today is more comfortable and more productive for more people than one of yesterday.

If we lined up 100 grading and excavation contracting workers and tried to find a car that would suit all of them, we’d have a difficult time. And when we try to fit the same 100 people into one style of excavator or loader, the problem is magnified because the machine must be not only comfortable but productive too. And somewhere in our equation, the word “affordable” creeps in.

Ergonomics is not a new concept. The first book we found on the subject, An Outline of Ergonomics, or The Science of Work Based Upon the Truths Drawn from the Science of Nature, was written by Polish author Wojciech Jastrzebowski in 1857. But the revived interest in ergonomic theories to some extent must be the result of the graying of our work force. Older employees with excellent experience and skills are managing their daily loads with bodies that are not as strong, not as agile, and probably not as quick to recover from injuries as they were 20, 30, or 40 years ago. Hand and wrist strength is not what it used to be; joints are less tolerant. Fortunately, the producers of many construction machines, such as excavators and loaders, have responded to these natural challenges, and the days when the only excavator operator who could cope with an eight-hour shift was named Bruiser or Tank are gone. At a site in Iowa last summer, we saw a petite Sylvia doing an excellent job.

To categorically call any product “ergonomic” seems to be courting potential disaster. Manufacturers are wise to mention the features that are ergonomic or worker-friendly and let the buyer or renter select the equipment most suitable for his specific crews and applications.

Little Things Can Mean a Lot

Most workers in our sector use hand tools as well as the bigger equipment–dozers, excavators, and loaders. Although they say it can be a relief to climb out of a big machine and work on smaller, ground-level jobs for an hour or two, handheld tools can create just as many problems. One of the most common causes of user fatigue in hand tools is the trigger. Isolating the trigger from as much vibration as possible is a good start, but the actual shape of the tool can be important. “A trigger should have good pressure distribution, isolated vibration, and a line of activation in line with the finger or toward the center of the wrist,” stresses Cynthia Roth, CEO of Ergonomic Technologies Corporation in Syosset, NY. “The trigger fingers should fall in line with the user’s grip.”

Similar attention should be given to all the small controls inside the cab. Joysticks and rocker switches can be easily held, or not; they can be within easy reach, or not. What if the operator is wearing gloves? Are the controls still easy to manage? Roth also reinforced the idea that much of the attention given to ergonomics has been inspired by the increasing number of excellent older workers whose mental skills and attitudes are highly prized by employers, but whose physical strength and dexterity are not as sharp as they were, say, 20 years ago. Making machinery ergonomically acceptable for this snoop of workers is not impossible and is worth its development many times over because of the benefits it brings to employers: efficient production from skilled, motivated workers.

One example of successful ergonomics in a cab is the Advanced Control System (ACS) from Bobcat Company. The ACS is used for selecting hydraulic lift and tilt functions in compact track loaders and skid-steer loaders, and it gives operators the ability to choose either hand or foot control in seconds, simply by pushing a rocker switch on the loader’s dash (on the Bobcat 753 and larger models). The system allows a number of operators to choose their preferred control option and, instead of having two machines–one with foot pedals and one with hand controls–owners can satisfy different operators’ preferences with the single ACS-equipped loader. “Users spend more time in the loader,” notes Lynn Roesler, product manager for loaders at Bobcat Company. “They earn their living in those machines. They want better visibility, less noise, and to be more comfortable. They want to be more productive too.”

The 7000 Series of skid-steer loaders manufactured by Gehl offers features to make their operation more user-friendly. The quiet operator’s platform has plenty of space, with more shoulder, head, leg, and elbow room. The deluxe suspension seat (optional on the 7600 but standard on the 7800) provides lumbar support and adjusts to the operator’s weight for a long day of productive work. The word “interact” was used by Noy at the beginning of this article, and that aspect of ergonomics can be seen in the quality of visibility from the cab and the ability to adjust oil flow to different applications. On the Gehl 7000 loaders, a grid section and window are located in the ROPS/FOPS; they help improve the visibility of the bucket. Without leaving the seat, an operator can adjust the hydraulic flow on the go, with less flow for the slower attachment speeds and higher flow for attachments with faster actions. Ventilation, heating in the cab, and air conditioning are all features that interact to make the machine’s operation more comfortable and productive.

The information we received about the M Series of loader/backhoes manufactured by Case Corporation (five models with horsepower from 73 to 99) mentions the Pro Control System first. “We’ve taken the best loader/backhoes in the industry and improved their performance, ease of maintenance, and control,” points out Rusty Schaefer, Case marketing manager. Doesn’t that sound like ergonomics in action? In this series, the cab features 23% more square feet of glass and the redesigned side latches mean reduced sight restrictions. The rear posts were reset by more than 3 in. for a wider view through the exclusive, three-section sliding window. Access to the cab is improved with a wider step and larger grab handles. “We talked to our customers about operator comfort and it shows with the M Series,” adds Schaefer. “Operators who spend significant time at the controls will quickly appreciate the view, the comfort, and the smart use of space in the cab. These improvements are sure to be appreciated by skilled operators and novices alike.”

Visible Progress

Along that same vein, Komatsu’s research has shown that contractors say one of their biggest challenges is getting employees–not qualified employees, just employees, period. Most of the machines from the last 10 years are vastly different from those designed in the 1980s. Back then, many cabs were primarily for weather protection. With the development of such models as the Komatsu Avance, it actually became an integral Komatsu design criterion to pursue operator comfort and ease of use. (Potential operators need to know that today’s machines are not like those bumping, jarring, noisy things they might have seen in elementary school films and books.) But how do designers know if their developments are working?

Every year, Komatsu’s product managers and designers go into the field to survey equipment users and find out what they like about the current product and what new improvements they’d like to see. Their findings are then used to make those improvements.

“The overall ease of visibility for the Case CX Series excavators is much improved,” observes David Wolf, marketing manager for excavators and loaders. “That is one of those subtle and often-overlooked aspects of ergonomics. It prevents some of the neck twisting that operators used to need to see their work clearly. A similar benefit comes from the adjustability of the seat and controls. If you are trenching, for example, you can move the seat forward for a better view but keep the controls back so that they don’t impede your view unnecessarily.” The controls of the CX excavators are separate from the seat. Other features mentioned by Wolf include the reduced effort required to handle the controls and the lower noise level in the cab. “The six silicon-filled viscous mounts that float the cab isolate it from vibrations, noise, and shocks,” he adds.

Wheel loaders are better too. The cab of Case’s 621D and 521D has plenty of glass for the sight lines the user needs and a panoramic view of the work site. The contoured rear hood helps the view to the rear. “Apparently small items, like the angle we have put on the steps into wheel loaders in the D Series, are important to operators,” notes Wolf. “We’ve learned this from our customer focus groups. The wheel loader steps are more like those of a ladder than the rather awkward style they used to be.” This might not be strictly ergonomic, but what about information so the operator knows what is happening to the machine? Does that not make the work easier, safer, and more efficient? In the D series loaders is an electronic information center that provides displays of the machine’s diagnostics, as well as gear, transmission modes, turn signals, speed, engine coolant temperature, oil pressure, and hydraulic temperature.

All this consideration for the operator is beginning to sound like what we expect from our personal cars. It’s obvious that most manufacturers are developing excavators and loaders that are operator-friendly (or ergonomically better than they used to be), and you can be sure that each manufacturer is well aware of the work done by competitors. This can only benefit users. We have mentioned features from different manufacturers, but it would be more useful to list what is available and then see if your favorite manufacturer offers it.

Kobelco, for example, has just announced its newest version of the ED 190 Blade Runner, described by the company as “the world’s only true excavator dozer.” As an excavator, it has a digging force of 24,900 lb. and an arm crowding force of 17,200 lb. With the Kobelco Power Boost feature, the operator can increase digging forces by 10% with the touch of a single button on the joystick. Easy installation of attachments is helped by two optional valves in addition to the standard breaker valve. Using them would mean that attachments could be installed without disassembly of the main control valve or draining of hydraulic fluids. The work modes offered on the Blade Runner–manual, assist, and breaker–are related to ergonomics too. Other makers offer similar options. They are all worth closer investigation as they contribute to better control of the machine.

According to New Holland, the most important upgrade to the LW50.B and LW80.B wheel loaders, which came in the spring of 2001, is in the operator’s compartment. The cab has been redesigned for more ideal form, fit, and function. Enhancements include a seamless front windshield, new suspension seating, improved storage space, and better comfort. With the transmission control integrated into the implement control for full control of the functions, the user’s left hand is free to operate the steering wheel. And the rounded rear hood is not just for looks; it improves visibility.

All the machines used by grading and excavation contractors have improved ergonomically in recent years. Ergonomic improvements largely mean that the cabs are better, with more room for the operator, better visibility, controls that are easier to reach and handle, less noise, and a general level of comfort that permits the operator to work a full day without serious fatigue or stress. It should certainly help in the recruitment of the right employees when you can offer these much-improved machines that treat their operators as well as they dig and load.