 |
May 26, 2004
Subscribers: 34,648 |
| Today's
Tip: Where to Sample for Wear Debris |
When it comes to wear metal trending, it is a mistake
to sample downstream of filters, allowing important
data to be stripped from the oil prior to sampling.
Equally corrupt is the common practice of sampling
large centralized reservoirs such as with steam
turbines, paper machine lubes and hydraulic systems.
The large volumes of oil in these tanks will dilute
wear metal concentrations to levels often below
instrument detection limits. Sampling live-zone
return lines and bearing drain headers is greatly
preferred.
| Book
Bits: How to Keep Bearing Lubes Healthy |
From the "Rolling Bearings
Handbook and Troubleshooting Guide"
Temperature is the primary factor that affects
the life of a bearing lubricant. Lubricant temperature
is influenced mainly by bearing speed, bearing load
and ambient temperature. The lower the temperature,
the longer the lubricant will last, excluding low-temperature
limits.
Base oil viscosity, thickeners and chemical structure
can all contribute to different operating temperatures.
Some greases will churn in high-speed bearings and
cause overheating, whereas a channeling-type grease
may function satisfactorily at a much-reduced temperature.
| Lube-Trivia:
What's the Scope of This Grease Test? |
Test your knowledge and prepare for ICML
lubrication and oil analysis certification.
QUESTION: Is the dropping point
of a grease a guide to maximum useable temperature?
Get
the answer.
Q
& A: Why Your Greases' Base Oil
Viscosity Is Important |
"Is it important to consider the
viscosity of the oil used to make a particular grease
if they both have the same NLGI 2 rating?"
It is critical to consider the base oil viscosity
when selecting a grease. The NLGI number relates to
the consistency of the grease, not its viscosity per
se. It is possible to create NLGI #2 grease using
ISO VG 10 base oil or ISO VG 1000 base oil. One would
never use ISO VG 10 oil in an application that demands
ISO VG 1000. We shouldn't casually consider the base
oil requirement when selecting grease. As an example,
open gear greases are frequently NLGI #0 or #00, but
they are made using very high viscosity base oil.
Drew
Troyer, Noria Corporation
Submit
a question
| Post
of the Week: Troubleshooting Noisy Hydraulics |
To reward the lubrication and
reliability community for its participation in the
Noria Message
Boards, we've started the Post
of the Week award. Every week, we award one lucky
member $50.
This week's award goes to:
Marty
Here's an excerpt from the post:
"Your problem may not be the oil
at all. I would first look at the pump. Check the
coupling or pump shaft to see if it is damaged or
slipping. Also check the pump to see if it has a bad
bearing. Next, check the pump pressure to see that
your relief valve is set correctly.
Next, check your engine rpms. If the
engine is actually working at higher rpms, the pump
can be trying to put out more flow than it is rated
at. This will cause a noise in your system and can
also give indications of air or cavitation due to
fluid velocity being too high. Once these are checked,
then I would continue to troubleshoot the system from
the pump out to the cylinders. Look for leaks, cracked
fittings, crimped or damaged lines, etc. " See
the entire post.
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