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Excavators might be the
most visible of construction machines because most building projects
and remedial applications require some excavation. In addition,
the success of attachments in recent years is testimony that the
more you can do with one machine and one operator, the more that
team becomes a profit center for your business. Anything that enhances
the performance of your machine will probably bring in extra income,
but it might not always be because the machine works more quickly.
The wide range of excavators
available reflects the depths to which the buckets must dig and
the amount of earth they are expected to move with each cycle. Sometimes
it is the job site itself that is a challenge, not the amount required.
Compact excavators seem to be growing in popularity, and not only
in confined spaces. Some observers say they are making inroads into
the traditional territory of the backhoe. But don’t forget
the big excavators, still the ideal solution at many sites. Texas
Crane Services of San Antonio, TX, has an excavator that can reach
out 82 ft. and excavate the material (from a river, for example)
in doses of 7,280 lb. "It is called a VC long-reach excavator,
produced initially almost 30 years ago by a British company, Priestman
Brothers, and now owned by R-B International," explains Brian
Hancher of Texas Crane Services. "It is sometimes called a
draghoe and offers two unique features. There is a variable counterweight
and a cable in-haul rope. Where other excavators have a fixed counterweight,
this machine has a counterweight automatically positioned by a hydraulic
cylinder to counterbalance the bucket and its load." The maximum
ground-bearing pressure of the VC (a machine whose gross vehicle
weight can reach 150,000 lb.) is less than 3 lb./in.2
The winch and cable system, mounted on the base of the boom, pulls
in the bucket and its contents, offering 26,460 lb. of breakout
force. "This excavator has been most popular in water control
projects," notes Hancher. "Our excavating contracts have
included pond maintenance for golf courses." Could it be a
viable alternative to dredging services for thousands of private
and public ponds nationwide?
Also related to water,
the weight of an excavator, and the difficulties of working on soft
ground is the equipment of Wilco Marsh Buggies, based in Marrero,
LA. "Wilco Marsh Buggies is an excavation contractor and also
a manufacturer, specializing in soft terrain," explains John
M. Wilson Sr., president of the company. "Our years of on-the-job
experience have been in levee work, swamp logging, oil-field work,
disaster rescue, high-line construction, land reclamation, and hazardous
waste cleanup." Basically, contractor Wilson has taken excavators
and mounted them on crawler systems that ride or float across soft
terrain on amphibious, self-powered hydraulic undercarriages. The
hydraulic drive (using a standard travel motor and brake from the
excavator) is mated to a planetary gearbox. The most popular size
has been the 1.25-yd. excavator, but buckets from 0.75 to 1.5 yd.3
might be better at some sites. The Wilsons have adapted Komatsu
(such as the PC60-5), Link-Belt, and Caterpillar excavators for
this special soft-terrain work.
Not every contractor
needs something extra from his excavator (especially if the company
owns a fleet of supporting equipment), and standard configurations
and attachments from manufacturers can accomplish most excavator
tasks. "We don’t need to adapt our excavators," says
Fletcher Donaldson of 3D Excavators in Doralville, GA. "We
have handled our projects with standard equipment. Those projects
usually involve the complete preparation of a site for construction
and could include sewer lines, sanitary sewers, storm drains, fire
protection lines, and domestic water lines." The company’s
fleet of Caterpillar construction equipment has handled such jobs
as the E*trade project in Alpharetta, GA, where some 50,000 yd.3
of material was hauled away.
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| Being
able to move the bucket as if it were controlled by a wrist
enables the operator to work from the same position for much
longer. |
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| Many
adaptations seem to be related to water, such as this job in
Wisconsin. |
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| This
excavator has two adaptations: a long reach and a PowerTilt
wrist. |
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| Some
adaptations are made for specific projects. |
"We will change
attachments, like buckets and concrete crushers, but we have not
altered the booms or sticks of our excavators," affirms David
Hood of Kirkwood Excavating in Fenton, MO. Kirkwood performs the
kinds of general excavating work that thousands perform on a daily
basis. Most of the contractors with whom we spoke nationwide have
not changed the machines they bought, except to add attachments
for different work.
"Our projects are
in the utility, telephone, and water segments of the construction
industry," reports Kevin Thiemann of General Excavating of
Lincoln, NE. "There are few occasions when we could justify
costly adaptations of our excavators. I think those who frequently
have unusual conditions, such as wide waterways, would appreciate
special booms for long reach, but our company name says what we
do, and we are happy with the excavators in their normal configurations."
Scott Johnson of Johnson
& Sons Excavating in Naselle, WA, sums up the situation well.
"No adaptations here. We couldn’t live without our thumb,
and I would consider a quick coupler and PowerTilt next time
around, but other than that we don’t really have much use for
anything else. I’m always watching the magazines for something
unique though."
One of the problems with
the rapid expansion of communities is that the ground on which they
want to build new structures is not always compacted enough. Building
over old landfills would be an example of this kind of work, where
compressible or collapsible solid or fills require some treatment
of limited depth before the actual construction begins. Excavators
can play a role in this too. Similar to a piling hammer, BSP’s
Rapid Impact Compactor has a foot with a diameter of almost 5 ft.
that stays in contact with the ground while a weight comes down
from about 5 ft. at the rate of 40-60 blows per minute. The speed
makes up for the energy difference between this method and dropping
a heavy weight from a crawler crane’s jib, and there is no
flying debris. Using an excavator is considerably faster. This adaptation
of an excavator has been successful at sites where the ground is
not ready for construction in its current condition; it could be
granular fill, fine sand and silt (dangerous when wet!), or land
that used to be landfill with rubble, brick, wood, and older domestic
waste. The depths compacted by this method have often been in the
1- to 5-yd. range.
A long reach has proven
useful for demolition work with tall buildings, just like the ladders
on a fire truck, when stability and safety are essential. If the
boom and bucket of the excavator are stretching 20 ft. or more farther
than normal, up or out, the inclination to fall over exists as it
would if it were holding a 20-ft. solid steel pole across a river.
Most manufacturers of large excavators offer versions suitable for
special applications and the enhancements include not only the longer
reach but also reinforcement to permit the adaptation and retain
the machine’s stability. On Case’s long-reach models,
for example, the speeds of boom and swing would be optimized to
ensure smooth movements. Having the necessary power and hydraulics
available might be the first challenge to meet when you want to
expand the capability of your excavator. To protect operator and
machine, Liebherr offers the Automatic Reach Limitation that calculates
the stability data and shuts down automatically if the predetermined
safety distance is exceeded. This reinforces a point made by several
contractors: If you are going to use a long-reach excavator for
demolition, you’d better make sure that your operator knows
exactly where the breaker attachment is headed, because it is meant
to break what it strikes, and it should strike only what you want
it to. Liebherr considers another practical aspect: The cab has
a protective shield against falling debris, and the user can request
a cab that tilts up as much as 30º to improve the operator’s
view of the work. The cab can also be raised almost 8 ft.
There is, of course,
more to extending the reach of an excavator than just welding more
metal on a standard boom. Caterpillar’s Ultra High Demolition
(UHD) excavators can reach a working height of more than 120 ft.
They have a variable gauge undercarriage to give them a stable working
platform. There are three UHD fronts available, each with a retrofitable
boom foot onto which a boom nose is pinned, a fore or intermediate
boom, and a stick. Other practical aspects of these factory-modified
excavators are the acoustic warning device that alerts the operator
when the boom moves out of its recommended working range and a variety
of work tools, guaranteed to match the excavator. That matching
is essential to safe, efficient work. On Volvo’s EC-Series
hydraulic excavators (EC140, EC210, EC240, EC290, EC360, and EC460),
the standard-duty boom can be combined with several different arm
sizes to match different applications. For mass excavation, a heavy-duty
boom and arm with a larger bucket cylinder is available, and a two-piece
adjustable boom might be the answer for work in confined areas.
Volvo offers the long-reach adaptations too.
Most excavator work requires
digging to a precise grade, often requiring an extra laborer with
a measuring rod. This is true where the depth or damage control
is a critical factor and is especially relevant to long-reach work.
A cheaper and even better solution is to install a depth monitor
inside the operator cab. Excavator depth monitors show the depth
of the bucket tip, as well as slopes and distances around the excavator.
Depth monitors available from Spectra Precision, Topcon, and Ocala
Instruments range in cost from $6,000 to more than $30,000. These
devices can greatly improve the quality of the excavation and decrease
labor costs. Some units, such as the newest model from Ocala Instruments,
headquartered in Orlando, FL, are wireless, greatly decreasing installation
time and costs.
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There is a tradition
among contractors, especially those with a rural, solve-your-own-problems
heritage: They or their employees can manage the design and fabrication
of adaptations for equipment. Look at the number of tractors, combines,
loaders, and trucks that have had such work done, and it is not
just a matter of the operator carrying baling wire and snips under
his seat! When it comes to larger equipment, such as excavators,
having adaptive work performed by specialists might make more sense
in terms of weight and cost. Such companies as Kocurek Excavators
of Suffolk, England (started in the UK but already fielding many
requests from North America), specialize in the design and production
of long-reach booms for waterway, materials-handling, and demolition
work. For a Volvo SE450 crawler excavator, for example, Kocurek
designs and makes a long-reach boom and stick arrangement (28- and
21-ft., respectively) to turn the standard 45-mt (50-ton) machine
into a 52-mt (57-ton) version with a maximum reach of almost 50
ft. and a dump height of 46 ft. How does this specialist approach
the work? First, each machine is different. The customer will say
how much production is required and which base excavator he wishes
to use. The Kocurek engineers then determine if there are any additional
features required (such as auxiliary hydraulic circuits), and the
drawings are made. All aspects are considered, especially those
of stability and safety, plus any special circumstances that might
dictate any slight difference in this particular machine. Then the
adaptation is manufactured for that machine.
Paul Wever Construction
Equipment Company (PWCE) of Goodfield, IL, specializes in adaptations
for excavators and other construction machinery. It approaches each
application as a separate, specialized challenge. One of its products
is the Extendavator, designed to add an extra 8-50 ft. This product
does not require additional counterweight, can be left installed,
and transports easily because the clamp that holds it to the dipper
stick folds. The Extendavator has been successful on a Case 9030,
a Komatsu PC 220, a Cat 330, and John Deere 690. PWCE also makes
an "extendable paw" and a "third stick." The
best way to understand the value of these adaptations to contractors
is to mention some of the applications. Conti Environmental of South
Plainfield, NJ, has a PC 1000 and wanted to dig an 85-ft. slurry
wall around a demolition project at the Inner Harbor of Baltimore,
MD. PWCE cut the boom of the excavator and added 20 ft. to its length.
A special 35-ft. Extendavator was made for Conti. On the other side
of the country, in San Francisco, CA, Atkinson Construction used
a Cat 22 excavator (plus an Extendavator and Hy-Lift option) to
reach up to 50 ft. with a 2,700-lb. hammer. The job involved the
demolition of substructure highway columns. "They told us 56,000
pounds was the project’s weight limit and that workers had
to work in a confined area of 27 feet from the center line of any
pillar. A larger machine or explosives would collapse the tunnel
under the highway, so we devised this concept for their specific
use," explains Paul Wever. The multipurpose Extendavator can
be installed and/or removed in about two hours.
Jarrod Boyle of Boyle
Excavating in Bloomington, IL, remarks, "It was great not to
have to move the whole tractor every time I wanted to pick up more
dirt." He used a John Deere 690E to reach 30% farther than
most excavators by adding an extendable dipper from PWCE. "With
the extra reach, we can pick up more dirt in a wider radius, and
that increases productivity. I think this would be a great asset
for anyone in dirt moving and demolition," adds Boyle.
As for the third-stick
adaptation, "It is useful in those markets where the ability
to slope close to your tracks is necessary," explains Bob Martin
of Martin Equipment, headquartered in Goodfield, IL. "My company
undertakes the unloading of barges and needs to unload material
close to the excavator." Cautions Wever, "The third stick
matches one excavator [such as a John Deere 450LC] and requires
a counterweight. It cannot be transported on the machine. The Extendavator
fits 99% of machines in its class and needs no counterweight, and
if the owner trades in his excavator, he can keep his Extendavator
for the new machine if it is in the same class."
When asked if they adapted
their own excavators, many contractors were wary of telling anybody
else exactly how they made changes. Some of them–for example,
those who work in specialized aspects of earthmoving, such as land
clearance–have developed tools or configurations to uproot
trees (even those trees native to just their part of the country)
and are not willing to tell others how they do it because their
adaptations have led to their business success. "Our adaptations
have made us the best in our type of contracting," asserts
Sam Chaney, a contractor in Arizona. "They are the result of
our own experience and know-how. We are considering letting others
use our methods and patenting the products, but they would be something
that another contractor would buy." Other contractors talked
of patenting and marketing their devices and adaptations. When you
look back a few years and perceive how many inventors and makers
of tools and specialized equipment–even companies with sales
of more than $100 million–have merged with, or been bought
by, larger manufacturers, you can appreciate why a contractor with
a successful adaptation might be cautious about telling competitors
about it.
Attachments for excavators
are not all buckets and hammers, and there is one type that can
help all others. "Having this swing attachment allows me to
do some different work, but mostly it makes the traditional excavating
faster and more efficient," Jerry Nypen says about Helac’s
PowerTilt. He works for the Lower Yellowstone Irrigation
District, which manages 400 mi. of waterways from Intake, MT, to
the Missouri River. It is an area of 56,000 ac. "We use the
PowerTilt on our excavators for sloping, cleaning, and construction
of ditches. It allows an operator to position the bucket of the
excavator rather than the whole machine." The excavators are
not huge–up to 50,000 lb.–but large enough to mean that
constantly having to reposition them can take valuable time. The
PowerTilt attachment is often described as a "wrist."
It will give up to 180º side-to-side bucket swing for excavators.
It pin-mounts to the dipperstick and has no cylinder rods or other
external moving parts exposed to damage. It has a built-in, mechanical
quick coupler designed to use the carrier’s standard original
equipment manufacturer buckets and attachments without modification.
Bucket swing attachments,
such as the PowerTilt, have a history of success in ditch-related
operations, but that is not the limit of their value. Because he
can do more work from one position, the excavator operator moves
his machine less. That could save an hour a day. Projects that use
these machines include the building of retention ponds with a Cat
312 excavator, a roadside embankment with a Hitachi EX-100, and
foundation work near houses under construction with Bobcat compact
excavators. Gradall describes the movements of its telescopic excavators
as similar to those of an arm and wrist, going up, down, side to
side, and rotating as much as 180º. According to contractors
who have tried these tools that imitate the human wrist, when you
can twist the bucket, you can work it around obstacles such as pipes,
go around corners on structures such as bridges, make natural slopes
for trenches, and reach places that the straight arm just cannot
reach. "It’s like finding the light switch in the dark,"
remarks one operator. "If you didn’t have a wrist to move
your hand around, you’d never do it."
Paul Hull writes on
construction and environmental topics for several international
magazines.
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