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There is probably no
other working environment in the world more severe than the one
that exists on construction sites. The temperatures can range from
near freezing all the way to Gobi Desert hot. The air is often thick
with fine particulates that coat filters and adhere to fluid spills.
The terrain is bone-janglingly irregular. The equipment is pushed
to the limits of its hydraulic pistons and pumps as it moves heavy
materials out of trenches into dump beds or across grades. In the
machines that move some heaven, but mostly earth, each component
has to be able to withstand this environment in order to make money
for the contractor.
Unfortunately, if you're
operating a piece of equipment, sooner or later some part of the
many systems that make up an excavator or grader is going to wear
out or break. The idea is to make the system and the components
that comprise each system last as long as possible in order to increase
productivity and lower cost-per-hour. If you have to run the machine
2,000 hours in a year to make money, but in actuality it only operates
1,500 hours due to 500 hours of component failure, your ability
to complete jobs might be jeopardized. You might have to either
rent a machine to make up for the lost 500 hours or delay job completion
while repairs are made.
The Equipment Two-Step:
Starting With Your Best Foot Forward
Adding life to severe-duty
components is a two-step dance that starts the day you bring the
machine into your yard. Today's heavy equipment is a far cry
from those early creatures with simple levers that controlled a
couple of hydraulic cylinders and relied on the artisanship of the
operator to accomplish the task. The current generation of machines
is composed of an integrated system, often controlled by electronics
that monitor and adjust the machine for maximum performance in such
areas as air quality, fuel economy, and operation. Most manufacturers
provide a variety of support and services for the equipment they
sell to make certain that the customer understands how to operate
and maintain his new investment.
Almost all the major
manufacturers now offer maintenance programs that ensure that the
machines receive appropriate maintenance at scheduled intervals.
These service agreements add extra cost to the purchase. In many
cases, however, they pay for themselves by increasing the value
of the machine when it comes time to trade it in or sell it. These
programs also ensure that the machine receives the professional
attention it needs to keep it running in first-class shape. A variety
of service plans–ranging from extended warranty programs that
repair or replace components that fail, all the way to a full preventative
maintenance program–are available and should be investigated,
especially for smaller contractors who might lack onsite maintenance
staff.
To understand the machine's
operational and maintenance characteristics, proper orientation
and training become critical for guaranteeing long component life
and protecting against abuse. Onsite training and orientation of
both maintenance and operational personnel often is provided through
either the dealership or the manufacturer and might consist of a
full-day site visit from a representative. This onsite training
usually will consist of a detailed walk-around of the machine in
order to familiarize the operator with the various features, including
performance characteristics and limits, fluid check-and-fill spots,
and lubrication points. Most training also provides each operator
some time behind the levers to get a feel for how the machine handles.
Each machine has a set
range of operational parameters designed by the manufacturer. These
are the amounts of force that the arms might exert or the tonnage
that the chassis is rated for. One cause of premature failure of
various components is operator abuse of the equipment, stretching
it beyond what it is designed to do. "The biggest issue is
just operator abuse," notes Jack McCoy, marketing manager for
Luber-finer Filters. "In an excavator, for instance, if they
were to hook a bucket on a rock and try to break it loose, they'd
keep jerking it back and forth with the hydraulic system. The hydraulic
pulses can become great enough to cause failures not only of components
but also failures of filters due to the abuse that it is taking."
If the filter collapses and the operator is not aware of it, the
particulates that the filter is supposed to clean from the fluid
are now like free radicals, damaging values and surfaces and causing
premature wear.
The Equipment Two-Step:
Following Through
The second step of the
dance is the use of a preventative maintenance plan built on the
recommended service intervals of the manufacturer, as well as the
working environment of the machine. This requires the contractor
to establish appropriate management controls to ensure that the
operators are performing daily inspections of the equipment prior
to the start of work. A useful tool is an inspection book that the
operator must complete each morning and have signed by the foreman
or immediate supervisor. While the simple act of filling out the
book doesn't mean the equipment actually was inspected, it
does place greater accountability on the operator to perform the
inspections. A random audit program conducted by the supervisor
to verify the findings documented in the inspection book is also
helpful to ensure inspections.
These daily inspections
should begin with an examination of the running gear, hydraulic
cylinders, frame, and suspension for loose, bent, or damaged components.
Cylinder shafts should be examined for scoring, nicks, or leaks
that could be the precursor to failure. Engine coolant systems should
be checked for damaged hoses, leaks, or debris blocking the airflow
and causing an overheating problem that could lead to premature
failures. Missing fill caps, dipsticks, or other points where dirt
could enter the fluid systems should be addressed immediately. Axle
bearings, suspensions, pivot points, and all lube points should
be checked to see if there is any leakage or potential failures.
The engine and transmission should be inspected for leaks as well.
Fluid levels should be
checked each morning, and refilled as appropriate. On some equipment,
a visual sight glass or gauge shows fluid levels without opening
the system, while on others a dipstick or other manual measuring
device is used. "Where we see the most problems is when people
do not maintain the oil fluids correctly," relates Jennings
Nelson, general sales manager for Spicer Off-Highway Parts and Distribution
Division of Dana Corporation. "What typically happens–[for
example] in a power-shift transmission–when those oil levels
are not maintained properly, the clutches burn up and wear out."
When refilling, care
should be taken to clean the surfaces in order not to introduce
dirt or dust into the system. "They need to try and do it when
there is the least amount of dust in the air," states McCoy.
"That is not always the easiest thing to do, but the least
amount of time they have the system open to the air, the better
opportunity they have of keeping dirt from getting in." McCoy
recommends practicing good housekeeping on filling equipment, whether
diesel fuel, engine motor oil, hydraulic fluid, or coolant. "If
it's a hose coming from a portable tank or fueling truck, it
needs to be clean. Many times they [the hoses] are just hanging
on the back of a truck, and as they bounce down the construction
roads, they're subject to dirt. [The operators] need to wipe
off the outside as well as the inside of the nozzle."
Each fluid is designed
to perform a certain function in the equipment, and while hydraulic
fluid and transmission fluids have the same general appearance,
their formulations are completely different. McCoy also suggests
guarding against cross-contamination of fluids. "We need to
put a gallon or two of oil in the engine, and the hydraulic tank's
a little low too, so we need to put some in there. Don't use
the same bucket. Not only that, don't use a bucket [at all]
because the bucket is sitting in the back of a truck [and] dust
and dirt clings to it. Ninety percent of dirt getting into these
systems is due to mishandling, particularly in the construction
environment."
Breathing Air and
Rocking Along
Fluids are not the only
media susceptible to introducing dirt into the operating system.
The air entering the engine also needs to be cleaned to ensure proper
combustion and to prevent unnecessary wear of valves and cylinders.
"Those aren't necessarily wear parts," points out
Robert Fawver, national sales manager for Centri Air Precleaners.
"But it tends to be an area that receives the least amount
of the most improper maintenance. That's simply because a lot
of maintenance folks don't follow the manufacturer's recommendations.
We find a great deal of filter changes being done a number of different
ways that really don't follow what the equipment manufacturers
recommend. They'll change filters based on observation. They
will open the canister every time and every day and look, or they
will base it on hours. And neither one is what's recommended.
It creates a real problem."
Fawver states that such
overmaintenance can be as problematic as lack of maintenance when
it comes to air filters. "What that leads to is an overservicing
situation," he notes. "In most cases, people feel that
overservicing is a good thing, but in this case you actually can
do more harm to a diesel engine by overservicing the filter than
you can by underservicing. That is simply because as part of the
filter media, it's not as efficient until it becomes somewhat
dirty. It enhances and increases the filtration effect of the filter.
Most of the graders and excavators manufactured today come with
restriction gauges, and every engine manufacturer has a restriction
guideline. What they should do is put the filter in, close the canister,
reset the gauge, and don't open the canister until it reaches
that [guideline]. That way they are getting the maximum filter life.
[That way] they are doing less harm when they service the filters
and not allowing any extra contaminants to be drawn into the engine."
The Centri Air Precleaners
are designed to eliminate the majority of particulates that enter
the system. Through a variety of designed vanes, the air is directed
toward a spinning impeller that creates a centrifugal force, causing
the heavier particles to be expelled out of the airstream. "Our
precleaner is designed to remove particulates, help extend air filtration
life, and help reduce the maintenance costs at the same time,"
describes Fawver. "With this type of aftermarket apparatus,
obviously depending on particle size, you remove up to 90% of the
contaminants before they reach the filter."
Two other areas that
are often ignored in the routine maintenance, yet can have a significant
effect on the life of the suspension systems, are the bushings and
fasteners. "The reason that they do wear out is because they
are at a moving point at the suspension or pivot point," states
Rick Rickman, director of sales for Watson & Chalin. "The
most critical thing about the wearing of a bushing is that it's
held in place by a fastener, typically a nut-and-bolt. If the nut-and-bolt
is not tightened periodically or checked to make sure that it has
the proper torque, it will loosen. A loose fastener will cause premature
bushing wear."
Vehicles and equipment
involved in a lot of stop-and-go activities, such as dump trucks,
are particularly susceptible to this type of wear because of the
forward twisting forces that result when the truck's weight
shifts forward and back with each stop. "Another high-wear
point on a suspension is cornering or turning forces," adds
Rickman. "Some of our auxiliary axles are steerable and some
are not. The nonsteerable axles take a lot of side load when the
truck is turning. A steerable suspension minimizes side load because
it steers into the turn." Add to this mix the irregular terrain
that the typical off-road unit operates in, and these forces can
shift weight from side to side and from front to back repeatedly.
The Right Component
Is Everything
There is a tendency to
want to save money and to cut corners when it comes to replacement
parts and components, but this actually could lead to greater costs
in a penny-wise, pound-foolish approach. While many components,
from replacement filters to axles and transmissions, might look
the same, that great deal you've found might actually end up
costing you. The reason is that, unless the item meets the manufacturer's
standards and specifications, it might be increasing wear or allowing
contaminants to flow through the equipment.
"It's very
important that, even though filters may look alike and one filter
may screw onto that mounting base, they have the correct filter
for the application," cautions Jack McCoy. "In this one
particular engine, there are two filters that look identical as
far as the exterior look, threading, and mounting, but the media
inside are totally different. One is for mechanical injectors that
are much lower pressure. The other is for the newer electronic ones.
If you put the mechanical injector filter on the newer electronic
engine, they [the manufacturer] will actually void the warranty."
Often if a major component
has experienced sufficient wear, it's desirable to use a remanufactured
replacement. But it's critical to ensure that any component
meets the requirements of the original equipment manufacturer. "Why
would you want to jeopardize the performance of that equipment by
using unauthorized means of repairs?" asks Dana Corporation's
Jennings Nelson. "Obviously, in all industries today, equipment
uptime is absolutely critical. More and more contractors are really
measuring the cost of that equipment, what does it cost to operate
over the life or use of that equipment. Plus, with the market the
way it is today, there's obviously a lot of used equipment
being flushed back into the marketplace, and the smaller guy [is]
buying this equipment. Using genuine components has to add value
to their operations and their equipment. The value-added [benefit]
of coming back to the authorized channels is the optimum. Why go
anywhere else?"
Guest author Lynn
Merrill is director of public services for the City of San Bernardino,
CA.
GEC
- November/December 2002
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