The same philosophy holds
true today, and nowhere more critically than for heavy-duty off-road
equipment. Contamination of fuel, oil, and hydraulic fluids is the
primary cause of component failure in equipment, and therefore prevention
is a critical step. In order to enact an effective prevention regimen,
contaminants and their potential sources must be identified and
understood.
Phil Marheine of Filter
Technology Australia Pty Ltd. lists contaminants as particles; moisture
or water; other oils or fuels; or process contaminants such as heat,
soot, or coolants. Solid particle types include coal and stone dust
(typically from leaky sealants, breathers, or overheating); wear
metals such as gear, bearing, or shaft wear; or such manufactured
debris as leftover mill debris. They can damage equipment through
abrasive wear and surface fatigue.
Oil can be adversely
affected because contaminants can accelerate oxidation. Moisture
causes oil to thicken, losing its lubricating properties. It also
consumes and dilutes additives. The long list of sources ranges
from Mother Nature to man to machine. “The most likely sources
of contamination come from dirt ingestion and water contamination
in the work environment,” states Ed Newman, marketing and
advertising manager with Amsoil Inc. in Superior, WI. “Unlikely
sources include improper maintenance practices such as using the
wrong oil or failing to follow proper procedures.”
Bad Breath
“Bad breathers: It’s the first place to start,”
Marheine states empathically. Breather hoses can deteriorate or
become damaged if improperly used. They can even fall off. Breather
caps, or valves, in transmissions and hydraulic systems can become
caked with dirt, pop the seals, and cause the lubrication to leak.
“If they’re plugged, the pressure builds and dirt gets
sucked in,” says Vernon Solis, fleet and off-highway advisor
with ExxonMobil Lubricants & Specialties.
Dust and dirt are detrimental
contaminants. “Dirt can be the number-one cause of lubricant-related
catastrophic failure,” says Mark Betner, heavy-duty lubrication
manager for Citgo Petroleum Corp. in Houston, TX, who blames the
air-induction system for allowing contaminants into the system.
“Ambient air has particulates. It’s important to maintain
your air filters.”
 |
PHOTO: PARKER HANNIFIN |
| Parker CM-20 filtration tester |
Shell Lubricants Technical
Marketing Manager Dan Arcy says filters should prevent most problems,
but they aren’t bulletproof. Improperly sealed air boxes can
suck dirt into the equipment. “If the O-ring around the cap
of the air filter gets damaged, pin-hole streams of dirt can get
in,” explains Solis. A dirty air filter overdue for a change
can allow dirt to get past. If a filter is damaged, old, or improperly
installed; if the tubing is damaged; or if the media is wet, it
can spell trouble. “Eighty percent of contamination issues
occur because of two things: air filters and evac hoses.”
Marheine advises checking
the condition of the breathers and using a desiccant to control
moisture. “Water is a worst-scenario contaminant. It reduces
the strength of the lubricant, leaving metal on metal. Wear generates
wear; it’s self-perpetuating.” Sources of water ingression
include heat exchanger links, seal leaks, condensation of humid
air, inadequate reservoir covers, and temperature drops.
Other suggestions Marheine
offers include maintaining good housekeeping. “Don’t
put a hose directly into a breather; use a quarter-inch plug. Even
cleaning can introduce contaminants.” Check the rating of
the filter with a dealer to make sure it’s recommended by
the manufacturer, and avoid generic tools that aren’t designed
for the application.
Self-Induced
Even the engine can generate contaminants. Wear metal
acts as an abrasive that leads to oil breakdown, catalyzing it and
causing it to thicken. Depending on the engine manufacturer, copper
or lead may come from the bearings, and iron from the crankshaft.
That isn’t the
only problematic metal. Contaminant metals such as additive metals
and components of silica from dirt and antifreeze can have similar
abrasive effects. “Make sure the wrong product isn’t
added,” warns Arcy. “Adding hydraulic oil to the engine
can cause problems.”
Arcy considers dirt
and coolant the two major sources for engine oil contaminants. “Antifreeze
causes unseen damage to an engine. Monitoring varies from company
to company and is especially difficult when equipment is not run
by the same operator every day.”
“Coolant is the
number-two cause of lubricant-related problems,” says Betner.
“It destroys the viscosity of oil.” Coolant also introduces
corrosion inhibitors that lead to leakage. “Additives are
the biggest threat,” concurs Marheine. “People don’t
know what to believe, but think of it this way: You can’t
take sugar out of coffee once it’s blended. Nor can you take
additives out of oil. Molly can’t be filtered under 40 microns.”
Arcy says engine coolant
is often overlooked, but it’s an important issue. He suggests
a 50/50 mix, summer and winter. However, he cautions, very often
it’s not a 50/50 mix. “It might be diluted with a supplemental
coolant additive, especially if it’s a diesel. If there are
other additives in the system, they have to be protected from corrosion,
too.” If the balance is out of sync, he warns, your freeze
protection is compromised. “It turns to jelly. The engine
won’t pump, and eventually you’re looking at engine
failure.” However, if seepage is caught early, it’s
fixable, although not inexpensive to repair. Arcy says it usually
stems from a head gasket or cylinder liner leak.
Whenever a vehicle is
in for service, Arcy suggests taking a sample of the coolant to
look for debris, checking the freeze point for balance, and checking
the level of SCAs, adjusting accordingly. He also recommends using
an extended life coolant. “It has huge benefits, such as less
maintenance with better heat transfer, and it lasts longer. A lot
of the heavy-duty OEMs use it as the factory fill. Typically, you
get 600,000 miles or 12,000 hours. You may never have to change
out as long as the freeze point is OK and there’s no debris.
There are no drawbacks, no downside.” That’s one beneficial
change in the industry he’s seen. Another is the increase
in sales of pre-mixed (50/50) coolant. “You don’t have
to worry about mixing. It’s easy: Just pour it in and go.”
Engine contamination
can occur by way of the lubrication system. The fuel system is another
area of concern. If the fuel injectors are worn, they can produce
improper spray atomization and excessive fuel in the oil, causing
additional wear.
Soot is a byproduct
of the combustion process caused by idling; long drain intervals;
bad usage habits, such as heavy loads and short trips; and advanced
engine technology. “Oils are designed to disperse soot to
microscopic size,” says Arcy, “but can’t handle
high levels.” Acids, another combustion byproduct of water
vapor and fuel, are neutralized by oil, but, again, there are limits
to the levels oil can handle.
Oil Reserves
One of the most distressing sources of contaminants is
the oil itself. “The oil companies don’t like to admit
that their oil needs filtering,” says Marheine. Compounding
the problem, he adds, is the fact that “drums have particles
that get into new oil. It becomes a housekeeping issue. More and
more companies are going to plastic containers, and increasingly,
the mining industry is beginning to filter new oil. The OEMs are
certainly pushing it—even to the point of issuing specifications
in contracts for oil delivery.”
Betner elaborates: “How
you store and handle lubricants makes a big difference. If you put
oil from one container into another, make sure the container isn’t
dirty, dusty, or used for other fluids. You have to maintain the
cleanliness and the integrity of the inside of your containers.
Be sure to inspect and clean storage tanks.” He also urges
consideration when transporting lubricants, a vulnerable time that
enables contaminants to sneak in.
Betner is aware of the
much greater chance of add-oil contamination on a job site and suggests
warding off as much contamination as possible by cleaning the area
around where the oil goes in or taking advantage of a mobile service
unit. “They’re very sophisticated. Usually, they have
filters on their feed lines; that’s important. You should
always use best practices for dispensing and changing out or adding
oil.”
Another point to consider
is the type of oil. Arcy says mineral-based oil is still common
for off-road equipment, but others claim synthetics are taking over.
They’re less expensive, have better low- and high-temperature
stability, and pump better. Jim Girard, vice president and marketing
officer of Fiske Brothers, likes them because they have a longer
life and don’t oxidize as readily as mineral-based oils.
“They’re
becoming more recognized, although it still depends on the area,”
says Solis. “In Alaska, you want synthetics because they start
quickly: 80% to 90% of wear occurs at startup. Their pumpability
is better, preventing more wear, and they can handle higher torques,
larger loads, and severe environments without requiring any additives.
But don’t use synthetics when you have a leak. Fix the leak;
it’s less expensive.”
Whether mineral-based
or synthetic, Newman says a good lubricant should have “good
detergency and ‘dispersency,’ excellent rust protection,
good anti-wear properties, and excellent ‘anti-oxidancy’
to help reduce damage from contamination.”
The Human Touch
The greatest entry of contamination is due to humans,
Marheine warns. “The guys in the workshop need to understand
that. Anything you can do to reduce that scenario helps: Use lint-free
rags …”
That’s why Solis
believes education and awareness are critical. “It’s
the operator’s responsibility to perform daily inspections.”
Solis believes that letting operators take ownership of their preventative
maintenance helps. ExxonMobil lubrication engineers work with customers
through training courses. “We teach operators about oil analysis:
what it means and how to backtrack to determine cause and effect.”
 |
PHOTO: FUMOTO |
| Fumoto engine oil drain |
Len Licursi, with Parker
Hannifin Corp.’s Hydraulic Filter Division, agrees. “It’s
a training issue and a care issue. The best way to overcome apathy
is to give them tools and respect. Guys love gadgets; it’s
the easiest way to get them involved. A lot of operators want to
do a good job. If they have the tools and understand the benefits,
if the products are readily available, they’re more likely
to check.” The bigger problem, as he sees it, is convincing
upper management to include training and products in the budget.
ExxonMobil reps go to
the field to perform onsite inspections so they can make recommendations
and monitor through sampling, but Solis says if they don’t
follow up, operators are likely to return to their old ways. Norio
Mitsuoka, of Fumoto Engineering of America, manufactures a product
to help operators maintain good habits. The corrosion-resistant
forged brass and stainless steel engine oil drain valve, available
in 25 sizes ranging from 12 to 20 millimeters, offers a no-muss,
no-fuss alternative to typical plugs that can come loose, leak,
and strip threads. The ball valve design provides a straight flow
for efficient drainage and a perfect seal when closed. He also offers
the N-Type valve, with a nipple that accepts hose to allow draining
of the oil in hard-to-reach applications. “It’s also
good for oil sampling,” he says. “You can remove a small
amount of oil for testing without shutting off the engine.”
Although the valve doesn’t require tools to open, it doesn’t
open when it shouldn’t, thanks to a unique safety lock. “We’ve
sold $2 million in valves with only three or four incidents of opening.”
Bernie Hall, Checkfluid
Inc. manager, is in favor of systems that allow ease of accessibility
because he believes the best samples are live, when the machine
is running, but it’s safer not to crawl under a machine while
it’s running. He cites a line that can be threaded in and
routed out on the end of a hose to allow fluid to be remotely accessed.
“Try to get lines as short and small as possible to minimize
the purge volume, or dead volume,” he suggests.
“Two valves predominate:
the pushpin and the ISO-style 16x2.” He refers to the European-style
pushpin with a slightly different profile and to the “pushbutton,”
another style of valve developed by Checkfluid to extract samples.
“You remove the backup cap, push a button, and fill the sample
bottle directly without additional problems. It’s quick, clean,
and appealing. No additional probes are needed.” A one-time
use pushpin offers flexibility, with a tube that threads into a
sample bottle. “The cap version pops onto heavy equipment.
It offers a little more ruggedness.”
Analyze That
“Any good lubricant manufacturer should offer an
analysis program as part of their service program,” states
Girard. “It’s extremely important to get reports for
wear metals, additive levels, and oxidation for oil-type lubricants
and re-circulating oil, like in rock crushers.”
Newman declares it “the
first step to a good proactive maintenance program that identifies
the sources of contamination and prevents unnecessary repairs.”
Hall thinks there’s
great value in a sample program. “It gives you a heads-up
to the immediate needs so you can perform low-cost repairs.”
Arcy likens it to a
blood test. “It doesn’t tell you what’s wrong,
but it does indicate where the problem is so you know where to look.
Then you work backwards to find the trouble spot.”
The general guidelines
for service intervals indicate a benchmark frequency of 250 hours,
or 500 hours for hydraulic systems. Although Arcy advises adhering
to the equipment manufacturer’s recommendations, he says techs
work with contractors to set intervals based on conditions and applications.
The idea is to “take a look at fluid as it pertains to the
condition of the machine.” Everyone strives for extended drain
cycles. “It must be done precisely,” cautions Hall.
“You have to meet the target cleanliness standards established
by the component manufacturer.”
Cleanliness is determined
by counting the amount and size of particles in the fluid. The smaller
the particle, the more damage it can cause. The Solid Contaminant
Code ISO 4406 is the most common system for representing particle
levels. Hall notes that hydraulic standards are even more demanding
than engine standards because of the higher pressure.
ExxonMobil offers a
proprietary oil analysis program called Signum, with online system
notification. After training, the customer takes a sample, sends
it to the lab with a pre-printed label, and views the results online
within 24 to 48 hours. “You can look at your entire fleet
together in order to determine trending,” says Solis. Signum
maintains tight tolerances to protect the life of the equipment,
but the program can be customized. “This is so critical.”
Marheine agrees it’s
important to implement an analysis program but cautions about over-reacting
to a bad result. “Get three reports; look for a trend,”
he says. Betner concurs, “Do multiple checks to get a trend.
You have to know the wear pattern for that machine; you have to
know what’s normal. Then look for significant departures.”
“Don’t let
it become a useless tool,” urges Marheine. “It should
be a proactive tool. The sample must be taken from the right source,
and you must react accordingly.” Betner believes it’s
time to “force the envelope on learning to interpret analysis.
If they have a false alarm or misread a diagnosis, people become
skeptical. Keep in mind an analysis is a window of time; it’s
an in-the-moment science. The whole world could change tomorrow.”
He suggests working with the provider to properly interpret analysis
results. “Educate yourself about how to read an analysis.
You have to diagnose properly before you can address the problem.
Not reading an analysis properly is as problematic as the lack of
follow-up to it.”
Cost is not a factor
in deciding on an oil analysis program as much as lack of education,
claims Solis. “If you really want protection, you have to
pay for it.” “The cost of analysis versus the cost of
failure pays for itself,” counters Newman.
Fighting Contaminants
Through Filtration
Colby Dyer, of Philadelphia, PA–based Schroeder
Industries LLC, explains that even if a filter is correctly sized
to handle the fluid flow, it can simultaneously be undersized for
dirt-holding capacity, resulting in the need to change elements
frequently. Another common scenario is that filter maintenance is
performed at fixed intervals, regardless of conditions. If the filter
has insufficient capacity to last to the end of the interval, it
goes into bypass, resulting in contamination.
Ideally, filter housings
should have an indicator to warn the operator when the element reaches
bypass, but if they’re not located in an easily accessible
location or operators ignore them, they’re not effective.
Dyer says that’s when testing becomes crucial in determining
if the element will last through an interval. “Dirt-holding
capacity is critical if you’re changing at intervals. Take
a particle count when you do oil analysis in order to verify you’re
getting the life needed from the element.”
Two methods for increasing
dirt-holding capacity are to install a larger filter housing or
to use a filter medium with greater dirt-holding capacity. Both
can trigger higher installation costs, but a superior medium can
be significantly more cost-effective.
An offline system, working
much like a kidney dialysis machine, filters 20% of the oil per
hour. Marheine prefers that to an inline filter, which causes a
pressure drop. “The machine can’t operate due to the
fineness of the filter. Since you have to flow oil through the machine
or it will starve, it limits the ability of the filter to work.
You can get around that by bleeding off the oil, but it’s
better to have an offline system running on the unit.”
Solis says the use of
filter carts is increasing. “It’s very efficient, running
for several cycles. It’s designed to clean the transmission,
engine oil, and hydraulic lubrication of sludge and dirt that make
it to the pump.” Another handy item is a magnet, placed on
the drain plug to capture metal contaminants and contain them in
one area until cleaned. “Super magnets are more popular every
day,” Solis asseverates.
Dyer thinks most hydraulic
engineers and owners understand the importance of maintenance, but
the problem lies in getting the message to the operators. His solution:
Demand indicators on filters, specify sample fittings, make maintenance
part of the job, and require a report or it won’t get done.
The next step, according
to Marheine, is to introduce buggies or onboard systems. “It
all comes down to controlling contaminants to the highest level
possible.” Unfortunately, he says, buggies are too often parked
after the initial use.
Hydraulics
“Engines are tough to protect because of all the
combustion byproducts,” Licursi asserts. “But 90% of
hydraulic systems are closed loops never open to the atmosphere,
so if you have clean pipes, hoses, and tanks, and if they’re
at the correct temperature and pressure, they should never get contaminated.”
Of course, that scenario
serves more as goal than reality. Licursi lists potential contaminants
and areas of ingress: carbon from vein pumps, caused by wear; residual
slag and other contaminants from dirty valves; environmental elements
collected on the cylinder arm during the out stroke when the rod-wiper
seal wears out; human error in over-pressurizing the blow hose,
getting connectors dirty when changing attachments in the field,
or carelessly refilling the reservoir; and “hydraulic fluid
from the manufacturer isn’t clean.”
Hydraulic systems are
more sensitive to contaminants than engines, and 95% of construction
equipment managers don’t manage them correctly, according
to Betner. “If you wait for dirt to show up on the soil sample,
it’s too late.” One option is a particle count, which
shows a level of contamination a routine oil analysis won’t.
“It’s often neglected because everyone is focused on
the engine. Few people are even aware of how to monitor hydraulics.”
Newman says using kidney
loop filtration on a regular basis helps ward off contamination
trouble and can help remove contaminants if discovered. Licursi
says higher pressure in the mobile market is driving the use of
filter carts and kidney loops. “They want it faster and cleaner.
They want higher dirt holding and tighter filtration [3 microns],
and they want it to last longer. They want it all!” Licursi
laughs.
He advocates use of
a vac dehydration cart to diagnose problems. Sized according to
flow rates, the carts draw out oil, which is then boiled, de-gassed,
filtered, and returned to the reservoir as clean oil—all without
powering down, so downtime is eliminated. Portable units are available
in 5- to 20-gallon sizes or a 600-liter unit that runs continuously.
Citing the increasing
popularity of the carts, Licursi says the $80,000 price tag is balanced
by savings in waste disposal costs. “The EPA makes you trace
disposed oil, and if you put two dissimilar oils in a disposal tank,
they label it ‘hazardous,’ which is more costly to dispose
of.” He points out that since oil doesn’t wear out,
it’s cheaper to keep it clean through filtration than to replace
it and pay for disposal. “It can cost half the price of new
oil.”
Bearing With
It
“They require greases—thick, sticky greases,”
says Girard of bearings. “The biggest problem is that they’re
subjected to airborne contaminants from rock, dirt, water, and mud.
The greatest cause of bearing failure is dirt; it causes wear and
abrasion. You need a grease that seals out airborne contaminants.”
That’s not all.
You need greases that are shear stable, maintain their structure,
and don’t thin out. The advantages are that they seal out
airborne contaminants and need less frequent re-lube intervals,
which translates into less downtime.
You also need greases
that operate over a wide temperature range. “You don’t
want them to freeze in the winter or melt in the summer,”
chuckles Girard. “If the grease freezes in a front-end loader,
the bucket won’t move.”
Girard says since grease
analysis has less relevance than oil analysis, operators need to
conduct a site evaluation every day. “If they see fresh grease,
they know it’s OK.” If, however, they find contamination,
bearing replacement is likely. Another tip for preventing contamination
is storing equipment inside, although he realizes it’s not
always possible.
Words of Wisdom
“It’s a whole series of things: coolants,
greases, oils …” muses Solis. Although he says diesel
technology lags behind the evolution of gasoline engines, it’s
still changing all the time. “We have to be prepared. Not
all oils are created equal.”
According to Marheine,
contaminants—especially in the mining industry—are a
high priority. “There’s a lot of work being done because
there’s so much value in the extension of component parts,
even without the issue of oil prices going up. We’re doing
a lot of work with crusher lubricants. People change the oil in
machines, but what about the crusher? Rock-crushing silicon is the
hardest thing known to man. If the crusher stops, the plant stops.
It doesn’t matter if the loader works.”
Dubbing maintenance
“90% common sense once you learn the basics,” Dyer says
it’s a matter of motivation. For many companies, the bottom
line is the bottom dollar, and with maintenance programs saving
costs, they’re motivated to “pay now” because
it’s more economical.
Residing in Indianapolis,
IN, Lori Lovely writes authoritatively on transportation and technical
subjects.
GEC
- March/April 2006 |
