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Over the past 10 years
or so, heavy-construction equipment operators have added a new word
to their vocabulary: uptime. Or, more accurately, an increasingly
competitive construction economy has introduced them to the word.
More and more, managers are looking at ways to increase equipment
utilization and return on assets.
On a day-to-day basis,
one of the best ways to maximize uptime is to get serious about
preventive maintenance. Tracking equipment hours for the purpose
of scheduling maintenance to prevent problems before they arise
is one part of the equation, but the ideal would be a maintenance
program that both prevents continual major repairs and has maximum
intervals. Zeke Zakotnik would tell you that automatic lubrication
systems are a key component of an ideal program.
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PHOTO:
ALEMITE |
Zakotnik, equipment manager
of aggregates producer and general contractor Staker & Parson
Companies of Ogden, UT, can attest to the positive changes that
the automatic lubrication systems have provided Staker & Parson
in the past couple of years since the companies started installing
them on their equipment. “The
operator is the guy who’s going to run the machinery, not necessarily
maintain it per se,” says Zakotnik, who’s responsible
for the maintenance of about 70 front-end loaders, 25 excavators,
and 40 graders. The companies have installed auto lube systems on
all of Zakotnik’s excavators and loaders. “It’s not
what they do; they’re not maintenance people. We know that
the equipment is getting greased where it’s supposed to get
greased now.”
While it might never
be possible to fully automate earthmoving, mining, and paving operations,
lubrication is a function that makes plenty of sense to automate.
The pins and bushings on high-production machines like Zakotnik’s
equipment lend themselves to greasing at standard intervals, so
the systems don’t have to be particularly “smart”
in terms of detecting a low level of grease on key friction points
and dispensing lubricant, for instance. Greasing at standard intervals
maintains a “grease donut” around pins and bushings that
can last an entire shift or longer; each operator becomes an exception
manager with respect to the system by regularly monitoring it.
At the same time, the
systems allow the maintenance staff to function as maximizers of
equipment uptime. The reason? With reasonable certainty that the
lubrication systems are continually operating, the maintenance staff
can schedule pin and bushing replacement at regular—and, more
importantly, greater—intervals. This scenario prevents the
alternative of having to make major repairs at unforeseen times
due to catastrophic breakdowns, which can delay repairs of other
equipment and reduce the operating effectiveness of a significant
portion of the equipment fleet.
Zakotnik would tell you
that he gets a tangible return from the systems in terms of machine
uptime, operators’ productive utilization of equipment (in
contrast to maintenance), reduced replacement of pins and bushings,
and, most importantly, dollar savings.
Until a couple of years
ago, Staker & Parson operators would spend about 20 minutes
visually inspecting fluid levels and the condition of moving parts,
as well as lubricating the pins and bushings, at the start of their
shifts. The pre-shift walkaround is still necessary, but the task
of lubrication has been eliminated. This has cut the pre-shift downtime
by 50%, or 10 minutes. Multiply 10 minutes by 70 loaders and 25
excavators and you get an additional 15 hours of productive equipment
utilization per day. With operators making roughly $17 per hour,
that’s an additional $255 of productive equipment utilization
per day. Extrapolate that $255 over, say, 300 working days a year
and Zakotnik and Staker & Parson are getting an additional $76,500
of actual human operation of equipment every year
Just as importantly,
Zakotnik reports that his auto lube systems have cut the incidence
of pin and bushing replacement by 75%. “Now we can get a couple
of seasons out of a set of pins and bushings—before, it was
maybe twice a year that the mechanics had to go out and change those
out,” he says.
A residual benefit Staker
& Parson gains from the auto lube systems is in the improved
productivity of Zakotnik’s maintenance staff. “I would
say that for a 980-style loader, it’s probably saving our guys
20 minutes of grease time per machine,” he says. “Not
only is it saving the operators time, it’s also saving our
guys time to go out in the field to lube it.”
With manual lubrication,
“I know that when our lube techs would get out there, they
would completely grease the machine,” he continues. “I
know it would get done at least every 250 to 300 hours because my
guys were doing it, but the rest of the time, it was my hope that
the operators were doing it. A lot of times, we’d get out there
and the bucket would be squeaking. That’s just not what they
do; they’re not tuned to the fact that we’d have a dry
bushing or pin. Now, our techs just check to make sure that the
[grease reservoir] is full.”
Not to be overlooked
are the safety benefits of installing these systems. In many cases,
auto lube systems eliminate the need for operators and maintenance
staff to climb on equipment to lubricate pins and bushings, a practice
that carries plenty of risks of personal injury.
So the equipment, human,
and financial benefits of auto lube systems are fairly obvious.
But to the contractor who is thinking seriously of getting them
installed on future or existing equipment, the differences in systems
might not be. Here are some things to consider when taking the first
step in automating fleet operations by purchasing and using automatic
lubrication systems.
System Features
Two basic types of auto lube systems are available: progressive
and parallel.
The most common type,
the progressive system, lubricates friction points sequentially.
A pump that is controlled by a timer with programmed greasing intervals
makes lubricant flow from a central valve to the first secondary
valve in a series. Each secondary valve in the series lubricates
a friction point. A piston inside each valve precisely meters the
grease according to the requirements of the friction point in a
given secondary valve’s location, as the piston’s travel
is precisely set for metering.
In a typical progressive
system, as the piston moves from right to left, it forces grease
through valve outlets located on each side of the secondary valve.
The piston alternately forces grease through the valve outlets on
each side of the secondary valve via its side-to-side motion. When
the preset pressure at the lube point has been reached—forcing
the appropriate quantity of grease through the valve outlets—the
secondary valve closes, and the pump continues to generate pressure
for the next secondary valve in the lubrication sequence.
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PHOTO: VOGEL |
The most-often-cited
advantage of progressive systems involves system monitoring, to
be covered in greater depth later. But the primary advantage to
these systems lies in the fact that only one point—the central
valve, as opposed to multiple valves—needs to be monitored
for proper operation through various manual or automated methods.
On the flip side, this can be a disadvantage as well: If one lube
point stops taking grease, the whole system shuts down and the operator
might not notice it immediately.
Differences among manufacturers’
systems that the contractor should inquire about include the durability
and design of pumps and valves, as well as the guarding for lubricant
hoses—the most vulnerable components of a system.
It’s wise to ask
potential system suppliers about the corrosion and vibration resistance
of their pumps and valves, as well as what materials are used in
their manufacturing. Because these systems must operate in extreme
temperatures and high-vibration situations, the materials used are
critical. Without system reliability, the contractor might as well
continue manually lubricating the equipment.
A couple of manufacturers
offer parallel systems, which lubricate friction points simultaneously.
One advantage of this type of system is that if one lube point is
not being lubricated, the remaining points are still lubricated.
In addition, increasing the amount of grease output by switching
to a larger-diameter injector is basically as easy as changing a
spark plug on a car.
The design of pumps and
valves varies somewhat between both types of systems. One manufacturer
of parallel systems features pumps equipped with follower plates
that seal the lubricant from air and water condensation, which can
cause lubricant oxidation that is harmful to metallic friction points.
In regard to valves or injectors, the typical manufacturer uses
a spring that returns the piston to its starting position after
one lubrication cycle. A couple of manufacturers, however, use grease
pressure to return the piston to its starting position.
One of these systems
features a pump linked to distribution blocks, and each injector
is individually controlled by the pump, which has from one to three
outlets. The distribution blocks are designed according to the quantity
of grease to be dispensed to the lubrication points. The pump is
equipped with a sensor that records the number of pump rotations.
The system also features a lubricant reservoir equipped with a follower
plate located at the top level of the lubricant that protects the
lubricant from contamination.
Another significant concern
the contractor should raise with any manufacturer relates to protecting
the most vulnerable component of an auto lube system: the hoses
leading to the secondary valves. Invariably, contractors and manufacturers
cite broken hoses—a flexible and vulnerable system component
that operates in a harsh environment—as the most common cause
of system malfunction. So the extent of a manufacturer’s experience
with installing these systems with well-positioned guarding for
the hoses is an important inquiry to make.
Payback
Another way of looking at the benefits of auto lube systems
is to determine how quickly the systems pay for themselves. Zakotnik
knows that his systems pay for themselves in less than a year, given
the fact that, typically, his staff doesn’t need to change
pins or bushings on loaders and excavators within the first year
of installation—compared with the old practice of replacing
pins and bushings in the first year. His experience is consistent
with that of other contractors, as well as system manufacturers.
The more often the equipment is utilized, the shorter the payback
period because pin and bushing replacement would occur more often
in highly productive situations.
Brandon Frei, equipment
manager at Kennecott Utah Copper, oversees equipment maintenance
for one of the world’s largest open pit mining operations in
Bingham Canyon, UT. His payback on his parallel-type systems is
only 120 days.
“My pins and bushings
on my 980 loaders were going out every four months, and it was about
the same with excavators,” reports Frei, who oversees a fleet
that includes a combined total of about 90 loaders and excavators,
as well as 14 backhoes. “Now I’m getting nine months out
of my pins and bushings. And these are production machines; they
run 24 hours a day—it’s about double the life.” Just
one bushing change equals the cost of one of Frei’s auto lube
systems, he adds.
Prior to adopting the
auto lube systems, Frei and his staff lubricated the friction points
on earthmoving equipment manually, with all of the pitfalls of that
method. “We relied on the lube truck operators, who would take
turns going around,” he says. “We’d rely on the operators,
and we had twice the number of pin and bushing changes with our
980 loaders and excavators, and we couldn’t get a consistent
routine because we’d change operators so much. We’d have
to rebuild a 980 in two years.” Now, “All the points are
getting greased versus someone saying that they’re doing it.”
Frei says he first saw
one of the systems in operation on an over-the-road hauler truck,
which used its system for spring bushings and steering components.
“We started using the system on certified rebuilt [earthmoving
equipment], and then we started phasing them in at the rate of about
three a month,” he says. To date, about 70% of Frei’s
fleet is equipped with auto lube systems.
One manufacturer provides
software that enables customers to input the costs associated with
equipment repair, equipment downtime, and the labor required for
manual lubrication to help them calculate the payback period for
an auto lube system. Another manufacturer provides cost breakdown
scenarios for the payback its system yields for front-end loaders
and excavators. Including the costs of parts, repair labor, and
manual lubrication, the payback periods for a 200-horsepower front-end
loader, a 20-metric-ton excavator, and a 45-metric-ton excavator
are 12 months, 10 months, and under 10 months, respectively.
Monitoring
The typical contractor who has auto lube systems installed
on earthmoving equipment doesn’t delude himself into thinking
that the systems are foolproof, or that they are free of monitoring.
Although the savings these systems provide in dollars and time are
significant, the potential exists for these systems to detract from,
rather than add to, the operational efficiency of an equipment fleet
without a little vigilance.
Several means are available
to alert the operator and/or management that a system is malfunctioning.
In many cases, a light is mounted in the cab and goes on when triggered
by a proximity switch that is activated when a valve piston doesn’t
go through its motions, or if the switch closes the valve before
the proper amount of grease could have been dispensed. One manufacturer
of progressive systems offers an automatic relief indicator that
spouts grease when a particular valve is shut and does not take
in the lubricant. Although the grease flow continues throughout
the sequence of lubrication points, the automatic relief indicator
provides visual evidence of a system malfunction. Some systems also
send a signal when the grease reservoir gets to a low level. Alternatively,
the grease reservoir might be designed such that the grease level
is visible to the operator or maintenance staff.
One manufacturer’s
system features an electronic control unit equipped with a diagnostic
system that stores data such as service hours and fault codes. The
contractor can access the data by using software that is used with
a notebook computer or a more rugged handheld device supplied by
the manufacturer.
Kennecott Utah Copper
and Frei have gone really hi-tech with system monitoring. The company’s
auto lube systems are linked to a global positioning system (GPS)
location tracking system that also monitors the system lubricant
level.
“We do hold the
operator accountable if the grease does go down and we get a warning
light from the cab and a bushing goes down,” says Frei. “I
also run a GPS tracking system on my equipment, and I can also ping
them on my computer. It’s all connected to the system. If it
runs out of grease, it’ll tell me on my computer. If they’re
low on grease, it’ll e-mail the supervisor automatically.”
Regardless of available
technological indications of system problems, a task that should
never go away is the operator’s inspection of the machine prior
to the start of a shift, one that should already include a fluid
level check. During this walk-around inspection, the operator can
look for the “grease donuts” on friction points as an
indication that the auto lube system has been working properly.
Goo and Climate
Under normal circumstances, pins and bushings on loaders, excavators,
and graders should be lubricated with EP-2, also commonly called
No. 2 grease—whether they are serviced automatically or manually.
But the winter months, particularly in northern climates, might
force adjustments.
Greases are rated according
to density (and thus viscosity, resistance to flowing) and range
from EP-000, -00, -0, -1, -2, and -3 in increasing order of density.
EP-2 is categorized as medium-density grease and is recommended
for normal operating conditions and climates, important for forming
the “grease donut” that will last for hours of operation
even if an automatic system stops working; forms a barrier between
metal and dirt, dust, and moisture; and retains its integrity in
high operating temperatures.
In temperatures well
below freezing, however, the contractor might have to make adjustments
to keep the grease flowing.
The most common adjustment
is switching to less viscous EP-1 or even EP-0 grease during periods
of cold weather. Some manufacturers, however, offer pumps with variable
power. “We’ll go in and change the settings on the pumps,”
Frei says. “If the operator thinks it’s greasing too much,
we’ll adjust it. We have the automatic settings in the cab—low,
medium, and high settings.” Another solution to the cold-weather
problem is to design systems for cold-weather operation, meaning
pumps with higher ratios and pump lines with a larger diameter.
As for the chemical makeup
of the grease itself, some system manufacturers offer their own,
which is designed to prevent auto lube systems from getting clogged.
Auto lube system manufacturers warn against using grease with Teflon,
which is designed to increase water resistance, or graphite, which
sticks to metal and can clog the valves or injectors.
Sentiment toward the
additive molybdenum disulfide is mixed. Some manufacturers express
the same concerns about grease containing “moly” as they
do about products containing Teflon or graphite. But Greg Raley,
transport product application specialist for Shell Lubricants in
Houston, explains the value of this additive in off-road equipment
applications.
“There are a number
of equipment builders that specify 3% to 5% moly in some of their
applications,” says Raley. “When you start using a moly
grease, you’re really working your equipment hard. Moly is
considered a solid lubricant and helps with shock loading, like
when you drop a bucket, and hitting rock when you’re trying
to tear a piece of a mountain away—that’s where moly can
really help with shock loading and protect the bearings. I wouldn’t
use moly in what I’d call a high-speed bearing,” Raley
adds.
One manufacturer relates
the fact that the contractor can still use No. 2 grease in cold
weather, so long as the grease is designed for cold weather. The
question the contractor should ask is whether the lubricant has
a low cold test, making it more suitable for cold-weather use. Greases
with lighter base fluids and fewer polymers tend to yield a low
cold test. Aluminum complex is another material often added to grease
to increase water resistance, high-temperature operating ability,
and shear stability, but the presence of aluminum complex also makes
grease more thixotropic (subject to hardening), which makes it less
likely to pump through an auto lube system in cold weather.
The Case for Manual
Lubrication
Perhaps because of the initial cost of purchasing an auto lube
system and concerns about system monitoring, a few contractors still
believe in manual lubrication. And manual lubrication technology
is serving their needs. Battery-powered and electric grease guns
are making the manual lubrication process quicker and less reliant
on physical strength. An increased awareness of ergonomics and the
need for lighter weight exist, too. One manufacturer has designed
a portable grease gun with evenly balanced weight, a soft rubber
trigger, and a shoulder strap that allows the operator to climb
onto machinery with both hands free. In addition, the grease gun
features a microprocessor that maintains a constant pressure and
a motor that stops when the trigger is released, which minimizes
contact between the grease and air to prevent grease contamination.
Ralph Scheller, equipment
manager at JH Rudolph, an Evansville, IN–based asphalt and
concrete contractor whose parent company operates several quarries,
says that manual lubrication continues to work well for the company’s
220 pieces of equipment that include a few loaders and excavators.
Management did investigate
auto lube systems, but concerns about initial cost and monitoring
made the systems less attractive, Scheller says. “Most of our
machines are not assigned to the same operator, but the same operator
operates them about every day,” so they’re familiar with
their machines and take care of them, says Scheller.
But Travis Hartley, equipment
manager for Heber City, UT–based RJ Enterprises’ Utah
Stone division, cites greater reliability in auto lube systems as
the main reason why he prefers them.
Before, “It probably
took our people about half an hour to an hour to lube the pins and
bushings on an excavator,” Hartley says. “And by the time
you’d deal with all these grease fittings, sometimes they’d
be broken or damaged. Did he grease it every day, or just Monday
and Friday? You don’t really know that unless you’re watching
them all the time, which I can’t. The main thing is just the
overall satisfaction of knowing that it’s getting done—that’s
probably the biggest thing.”
Author Don Talend
is a former construction magazine editor who has written about construction
equipment and technology for nearly a decade.
GEC
- November/December 2005
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