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Just about anybody with
a piece of heavy equipment will tell you that hydraulic fluid is
the lifeblood of a machine. In fact, comparing hydraulic fluid with
blood is common among industry professionals, and the reason is
clear: Roughly 80% of hydraulic failures are the result of fluid
contamination.
It helps to think of
contamination as an infection, which is little more than the introduction
of foreign bodies into the bloodstream or other body parts. And
like an infection, contamination will only get worse if it’s
not treated. The most likely result: system failure and very expensive
repairs.
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Photo: John Deere |
| John
Deere's new Super Caddy is a filter cart that has a built-in
particle counter that allows a technician to filter hydraulic
oils to specific cleanliness levels. |
“If you get caught
off guard by contaminated oil it can get really costly,” says
Mike Daly, service marketing specialist with John Deere.
Luckily for heavy-equipment
managers, technology—with diligence—is making the task
of keeping hydraulic systems clean easier than ever. Filters, mobile
filtration carts, and fluid analysis allow contractors to stay on
top of maintenance, and to catch potential problems before they
shut down a machine.
The role of high-tech
products in hydraulic systems management mirrors the development
of the industry. It might seem that at one time you could top off
your reservoir with a garden-hose siphon and forget it, but those
days are long gone. Today’s hydraulics operate with the unforgiving
tolerances of nuclear reactors.
“We’re talking
about filtering down to the levels of red and white blood cells,”
says Al Zingaro, marketing manager of Parker Hannifin Corp.’s
hydraulic filter division. “In fact, the ISO [International
Organization for Standardization] code that is currently in use
to measure acceptable particles for a given size is in particle
ranges below that.”
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Photo: Caterpillar |
| Mobile filtering is just one part of Caterpillar's approach to maintaining a machine's hydraulic system. |
Big Problem, Small
Package
Some manufacturers call for filtering as low as 4 or 5 microns.
Given that the smallest visible particles are about 40 microns,
“What you can’t see can hurt you,” says Tom Blansett,
product sales manager for the western region for Eaton Corp.’s
hydraulics division.
To illustrate how small
the particles being filtered are, Blansett, who got his start in
hydraulics 28 years ago in submarines, notes that white blood cells
are about 25 microns, while red blood cells are around 8 microns.
If you ran your blood through a typical filter, he says, “You’d
be very clean, but you’d be dead.”
A hydraulics system can
fall victim to contamination from myriad sources: new oil, new components,
ingression, and internal generation. In each, filtering is the key
to preventing contamination, whether through the use of good filters
or a mobile filtering system. We’ll take a look at these to
see what owners and operators of heavy machinery can do to keep
their hefty investments hydraulically healthy.
New Oil, Dirty Oil
Most people who work around hydraulics will tell you that preventing
contamination begins with adding oil.
“New oil is basically
dirty oil and it should be filtered before it’s put into a
machine,” says Dan Schultz, directly marketed accounts manager
for Schroeder Industries, a leading manufacturer of mobile filtration
carts and filters for hydraulic systems.
Although the oil is refined
to exacting standards, its transfer through various hoses to storage
tanks and drums—all of which likely harbor unwanted particles—virtually
ensures its contamination.
“In a lot of cases
what is overlooked is when you add the fluid itself,” agrees
Zingaro. “Most new fluid isn’t clean enough for the performance
specifications of the fluid in working condition.”
Filter Carts
The solution, Zingaro says, is the use of a mobile filtration cart,
or transfer cart. Essentially dialysis machines on wheels—they’re
also called kidney loops—these carts work on a simple principle:
Take in new fluid from its drum, run it through a filter or two,
then pump the cleaned oil into the reservoir. They can range from
a simple single-filter unit to high-flow versions with multiple
filters, onboard particle counters, and printers to provide readouts.
“You can set it up so it will circulate the oil until it reaches
an ISO cleanliness level,” Schultz says. “Once it reaches
that level it will shut off and you can print out the data for the
company’s records.”
A filter cart, used properly,
makes maintenance sense and ultimately can save a contractor thousands
of dollars. “The benefits of filtration are you preserve your
oil, you don’t have to add as much, you don’t have to
replace it, it lasts longer, and your performance is better,”
Zingaro says.
Not every contractor
needs his own cart, but it makes some monetary sense for those with
several machines to have a basic filter cart. “The guy with
five or six machines, he should have a filter cart just for topping
off fluids,” Schultz says. “At minimum.”
Filtering new fluid is
the most common use of transfer carts, but they also play a significant
role in scheduled maintenance. Increasingly, say hydraulics professionals,
dealers and contractors use filter carts to get a machine’s
oil to a desired cleanliness level.
“A huge place for
them is in dealers, where they’re bringing in the customer’s
machine and servicing that machine,” Schultz says. “At
large dealers they’re using the carts to check the ISO cleanliness
level of the oils often. They run the filter carts on them to keep
the contamination levels down. We’re seeing a lot more of that.”
John Deere, in fact,
recently entered into the filtration cart market with its Super
Caddy, which the company calls the most advanced unit on the market.
“Super Caddy takes out particulates and free and emulsified
water,” says Daly. “It also has a readout that tells you
what cleanliness level you’re at, and what saturated moisture
level you’re at.”
Daly says the chief customers
of its Super Caddy are dealers who do maintenance. “The dealer
can take this out to the field when they do PM,” says Daly.
“It adds an element of visibility that in the past was strictly
ritual.” That visibility, he says, is provided by the machine’s
ability to count particulates in the oil. Such real-time feedback
lets a user filter a system to a specific cleanliness level. The
result: guesswork and hoping for the best are removed from routine
hydraulic maintenance.
Beyond the addition of
fresh oil, another crucial time to filter a machine’s oil is
after new components are installed. Hoses in particular are notorious
for harboring contaminants—slag, rubber, dust, etc.—simply
as a result of the manufacturing process. In addition, taking a
machine apart opens its hydraulics to contamination. Again, think
infection. Good dealers strive to keep their shops clean, but dust
and dirt are just facts of life. “When a dealer puts a system
back together,” Daly says, “we use the Super Caddy to
help us ensure that we’re setting the stage for a long and
productive life. You don’t want to leave the contaminants behind.”
If contaminants are akin
to infection, attachments can be a nasty source of trouble. Some
machines, like scrapers, have huge oil volumes with long lines,
and swapping attachments between them virtually guarantees the spread
of contamination. Not all machines are created (or maintained) equal,
says Daly, who warns that one “dog” in a contractor’s
fleet can easily pass along its contamination through swapped attachments.
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Photo: Schroeder |
| Schroeder's Mobile Filtration System is ideal for cleaning up systems or prefiltering new oil. |
“A lot of times
those systems are shared among different machines and they take
the failure mode of one machine and pass it to the other guy,”
Daly says. “Those are incidents with a machine that’s
a dog that’s gotten itself in a situation where it brings in
contamination and infects other machines. Fluid analysis and a caddy
are a good way to measure that. The caddy can help you recover from
that. In many cases the recovery from an incident is very effective,
so you don’t have to pitch the oil and go through a whole cleanup
on the machine.”
Filter carts won’t
take the place of analysis done in a lab, but they can be a vital
element in keeping your equipment in good shape. It’s what
Daly calls “optimizing maintenance … the idea that the
cart can help a contractor get the most of his maintenance budget
by the smart use of tools and technology.” Carts will do the
work, but determining when a piece of equipment needs service is
the contractor’s job. And, say the experts, it’s more
involved than simply following the manufacturer’s recommendations
based on service hours. An original equipment manufacturer (OEM)
might call for service at 500- or 1,000-hour intervals, but consider
the conditions under which most equipment works. “They’re
not operating in clean rooms,” Blansett says.
In machines that work
in a “severe-duty environment,” Daly says, filtering on
intervals as frequent as 250 hours might be desirable. “We
don’t know how dirty the oil is,” he says. A cart with
a particle counter, however, will tell you.
For contractors, filtering
their equipment so frequently may seem excessive. If the OEM is
fine with 1,000 hours, why mess with the schedule? “What might
seem like an extra step or cost might save you money,” says
Daly, who likens regular filtering to monitoring your health. For
example, statistics show that quitting smoking can add more than
a dozen years to your life. The caveat is that you have to do it
while it’s physiologically meaningful. “You don’t
go to your 64th birthday to decide to quit smoking to add 13 years
to your life,” he says. So it is with your machine’s hydraulics.
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Photo: John Deere |
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Photo: John Deere |
| Dialysis for the massive. |
Filters
Regardless of the machine used, you can’t keep a hydraulic
system clean if you don’t use good filters and change them
regularly. “A lot of customers might already have filter carts,
but you want to make sure you put a good-quality element in the
cart,” says Schultz. By that he means “a small-micron
element—high efficiency, high dirt-holding capacity. You want
to get the most bang for your buck.”
Filter makers do a balancing
act when designing elements, as Parker Hannifin’s Zingaro explains.
“I think the important thing for us is designing a filter so
there’s value,” he says. “It provides the very important
efficiencies of contamination control, but also it has the capacity
to give reasonable life for the customer. You could put a brick
in there and make it fit, and if it stopped everything that’s
good. But then of course there’d be no flow. What you really
need is an optimum situation where you get very good efficiency
so that you have at least 99%-plus for particle removal … and
yet you also have very high capacity.”
When Zingaro talks about
value, he doesn’t mean “cheap.” Yes, you can probably
save some money by ordering inexpensive elements, but remember that
you get what you pay for. And don’t forget how much you paid
for your heavy equipment.
“When you replace
your elements, you want to ensure you use a quality element. You’ve
got an expensive system here. You can buy elements … from anywhere.”
The problem, Zingaro says, is that “they’re not all qualified.
What you have are what we call ‘will-fitters,’ so it’s
tempting sometimes to buy the least costly element.”
Even the best filters
have a limited lifespan. Change them according to the OEM’s
recommendations, say the experts, or more often if you’re working
in particularly dirty conditions. Letting them go too long renders
them useless at best, harmful at worst. Rudy Urbano, senior marketing
consultant, hydraulic parts products, for Caterpillar, notes that
filters are designed with a bypass that allows oil to flow through
the element even if they become clogged with particles. The problem,
he says, is that as the fluid hits the clogged filter and flows
through the bypass, “It’ll begin to pull contamination
back out of the filter and into the system.”
Keeping It Clean
Filter carts and filters are just two of the factors in keeping
hydraulic systems clean and running at peak efficiency. Most manufacturers
of equipment and filtration products tend to take a comprehensive
approach to controlling contamination. Some, like Eaton, advocate
a “systemic” approach to oil cleanliness that targets
every aspect of a machine’s hydraulics. Caterpillar offers
its Custom Hydraulic Service, a series of inspections, analyses,
and solutions for heavy equipment.
Eaton’s Blansett
calls hydraulics “a highly technical area in a field that’s
seen as grunt-level.” Big machines moving large things in the
dirt might not seem like the stuff of science, but a hydraulic system
is indeed a complex chunk of machinery. Taking care of its oil will
simplify your life on the job site.
Jim Logan is the staff
writer for Forester Communications.
GEC - March/April 2005
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