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Ergonomic
advances enhance productivity and decrease injuries.
By Paul Hull
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.
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| Hands
and feet are working all day inside the cab. How often and how
much they move directly affects the physical well being of the
operator. |
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?
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| Ergonomics
is not simply a marketing buzzword; It's a way of making machine
design comfortable and efficient. |
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
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| The
handling of small controls inside the cabs of the largest excavators
can make a great difference to the day's productivity. |
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."
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| Good
visibility not only helps the work be more accurate but also
allows the operator to make fewer head movements. |
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
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| A clear
view of the work at hand will improve productivity. |
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| Fast
cycles come from well-designed, comfortable loaders. |
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.
Frequent contributor
Paul Hull writes on construction and environmental topics for several
international magazines.
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