Is cleanliness next
to godliness?
When it comes to
your hydraulic
system you’d darn
well better believe
it!
By Jim Logan
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.
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.”
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.
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.
Photo: John Deere
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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