Lubrication Procedure Saves Man-Hours
We recently installed new textile machines in our facility that
had more than 100 small gear assemblies per machine. The OEM recommended
procedure for the gear assemblies was to remove a number of side
plates along each side of the machine and then reach inside and
across to the other side of the machine with a long-handled brush.
Using the brush, we were to apply a coating of grease to one of
the gears while the machine is running. This would distribute
the grease to three other gears within the assembly.
would have required at least eight eight hours of labor and there
would have been a risk of contaminating the grease during the
application. Also, when removing the side plates, electrical components
would have been exposed, creating a safety issue.
one of the casings which held a gear assembly and found that there
was a small access hole in the front of the casting which would
allow us to insert a grease needle into the casting with no danger
of it contacting any of the gears. It allowed us to apply grease
to one of the gears quickly with no disassembly.
with the grease quantity, we are now able to grease more than
100 gear units in less than 30 minutes with no safety risk and
little risk of contamination.
is that even though a manufacturer may recommend a specific lubrication
procedure, it is good to scrutinize it to determine if it is in
fact the best method. This can also be done with recommended lubrication
frequencies which can vary greatly depending on the environment
and loading of equipment.
by Stan Morgan, Maintenance Engineer, Advanced Glassfiber Yarns.
How Multi-grade Oils Work
From "The Practical Handbook of Machinery Lubrication":
oils are made by blending a low viscosity oil with special additives
called Viscosity Index improvers. For example, when these polymer
additives are blended in the correct proportion with an SAE 15W
oil, the oil flows like an SAE 15W oil at low temperatures and
like an SAE 40 oil at high temperatures. The result is an SAE
15W/40 oil that will provide wide protection over an extended
the reliability of grease-lubricated couplings, use only greases
formulated for that purpose. General-purpose greases often have
thickeners that are heavier than the oil. When subjected to the
continuous and extreme forces of a spinning coupling, the thickeners
in general-purpose greases can centrifuge to the outside, leaving
the oil on the inside. Unfortunately, the outside is where the
oil is needed. The thickeners in coupling greases are equal in
weight to or lighter than the oil, ensuring that the wearing parts
in the coupling are well lubricated. (Tip submitted by Douglas
Branham, Lubrication & Reliability Mgr., Lubrication Systems
Company. Thanks Douglas!)
to High Temp Gearbox Lubrication
"We have a cooling tower fan gearbox, which due to the operating
environment runs very hot (>180°F). We recently inspected
the gearbox and found a lot of sludge and deposits and a strong
sulfur smell. Someone suggested we use synthetic oil instead of
the mineral oil currently used to prevent this from reoccurring.
What are your thoughts?"
While it is
true to say that synthetic oils can be used at higher temperatures,
because they do not thin out as quickly as the corresponding grade
of mineral oil, and provide better oxidation resistance, this
may not be the best solution in this instance. This is particularly
true, because the sulfur smell you refer to is likely the thermal
breakdown of the EP additive in the oil. Switching to a synthetic
oil will do nothing to prevent thermal additive decomposition,
if this is the problem.
A better solution
may be to install an offline cooling system by piping out a line
from the gearbox with a small gear pump to circulate the oil through
an external cooling system, returning the cooled oil to the gearbox
sump. Not only will this help to cool the oil and prevent thermal
and oxidative breakdown, it will also have the effect of increasing
the gearbox sump size, allowing the oil more opportunity to cool
A nice side
benefit of this arrangement is that the offline system can also
be equipped with a filter to help keep the oil clean, and an oil
sampling valve to take oil samples on a component that is often
difficult to sample on the run.
Senior Technical Consultant, Noria Corporation
track the formation of serious wear debris in machine components,
consider trending percent large particles (PLP) as part of your
DR Ferrography analysis. PLP will indicate the relative fraction
of the total ferrous debris that is indicative of serious wear
problems. Simply subtract the reported small particle concentration
from the large, and divide by the total. A shift from normal results
should prompt further evaluation.
Be sure to
watch particle counts, water content, spectrometry iron trends
and others as supplemental tests. Iron oxides (rust) is often
nonmagnetic and could result in a false negative, even though
those particles may still be wear particles of great interest.
Know the limitations of your tests for best results.
counter is helpful in providing information on:
abnormal wear conditions
effectiveness of corrective maintenance
identifying the need for ferrographic analysis
identifying the use of dirty top-up containers or dirty new oil
is a test that determines the concentration of elements in an
oil sample by measuring the light emitted at specific frequencies
as the sample is vaporized at high temperatures.
It is possible
to determine whether particles identified under your microscope
are two or three dimensional. First focus on the general background
of smaller particles. If the particle of interest is in focus,
it is two dimensional. The amount of refocusing necessary to bring
it into focus roughly indicates it's thickness.
AN (Acid Number)
and BN (Base Number) test repeatability is typically plus or minus
Double-check of Lube Specification Saves the Day
An important component of the safety systems at the Ontario Power
Generation facility in Pickering, Canada is the standby generator.
While preparing a plan to flush and refill the power turbine,
it was discovered that the Procurement Department had inserted
a "No Purchase" comment in the CMMS system associated
with the ISO VG 32 turbine oil usually used, recommending instead
that a different, less expensive product be used.
the two products, it was found that the original product was formulated
from a Group II basestock, while the less expensive product was
a Group I. The Group I basestock oil has a higher cloud point
(indicating a less refined product with greater wax content).
In the past, usage of this product had caused equipment problems
in cold-start situations. Cold oil in the coolers had a tendency
to cause large pressure drops across the filters, resulting in
low oil pressure trips of the emergency shut-down system. This
is why the Group II was used in this application.
the Procurement Departments error was identified before the inferior
product was introduced to the equipment, and therefore no damage
A quick call
to the Procurement Department reminded them that price differences
shouldn't be used as the primary criteria for selecting lubricants.
by Khalid Malik, Technical Engineer/Officer, Ontario Power Generation.
How Water Affects Additives
From "Fluid Contamination Control":
Water in tribological
fluids (other than water-based fluids) leads to a multitude of
problems in terms of system damage and failure. Perhaps the worst
threat of water contamination in storage is its reaction with
additives and the damaging reaction products.
a filter-clogging slime to form in fluids containing tricresyl
phosphate (TCP), an antiwear additive used in tribological fluids
where an alkali is present. If ZDDP (zinc dialkyl dithiophosphate)
is used as the antiwear additive instead of TCP, many deteriorating
mechanisms could exist; suffice to state here that ZDDP can decompose
to form hydrogen sulfide and, in the presence of moisture, transform
into a highly corrosive acid (sulfuric acid). Even in fluids of
the corrosion-prevention type, moisture causes an egg-white type
slime. According to T.N. Dean, when moisture is present, corrosion-preventive
additives can exhaust themselves by "wrapping up" the
moisture in additive and water dispersion.
When changing pillow block bearings with a cylindrical OD on the
outer race, be sure to clean the grease channel located in the
housing prior to installation of the new bearing. The grease in
the channel tends to attract dust and dirt over time. When the
bearing is changed, this dirt can become displaced into the grease
channel as the new bearing is tipped into the housing. The dirt
can either pass through the application hole in the outer bearing
race or plug off the hole, resulting in damage to the new bearing.
(Tip submitted by Greg Neuenfeldt, Dow Corning. Thanks Greg!)
Regarding last week's tip about using spin-on filters as air breather
filters on reservoirs and gearboxes:
If you plan
to use automotive spin-on filters for breathers, drill holes in
the base of the filter outside of the gasket area. Automotive
filters have a built-in anti-drainback valve that won't let air
out unless these holes are drilled.
filters, like those used in hydraulic applications and filter
carts, etc., don't require holes to be drilled.