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Power Transmission Engineering (PTE) Has Your Bearing Education, Training, and New Developments Covered Every Issue
February 14, 2017
PTE covers bearings in every issue, from application stories to technical articles and the latest technology from the major suppliers. Here is a selection of some of our most recent and most popular articles on bearings:
I was invited by Tom Astrene of TLT to write a response to the
July 2010 TLT article (Ref. 1). My rebuttal — “In Search of a Fatigue
Limit: A Critique of ISO Standard 281:2007” — was published
in Tribology and Lubrication Engineering, TLT, August
2010 edition (Ref. 10). While this article is also available online,
I will attempt to summarize the essence of my response.
Until now the estimation of rolling bearing life has been based on engineering models that consider an
equivalent stress, originated beneath the contact surface, that is applied to the stressed volume of the
rolling contact. Through the years, fatigue surface–originated failures, resulting from reduced lubrication or
contamination, have been incorporated into the estimation of the bearing life by applying a penalty to the
overall equivalent stress of the rolling contact. Due to this simplification, the accounting of some specific
failure modes originated directly at the surface of the rolling contact can be challenging. In the present
article, this issue is addressed by developing a general approach for rolling contact life in which the surfaceoriginated
damage is explicitly formulated into the basic fatigue equations of the rolling contact. This is
achieved by introducing a function to describe surface-originated failures and coupling it with the traditional,
subsurface-originated fatigue risk of the rolling contact. The article presents the fundamental theory of the
new model and its general behavior. The ability of the present general method to provide an account for
the surface–subsurface competing fatigue mechanisms taking place in rolling bearings is discussed with
reference to endurance testing data.
End users and OEMs frequently specify
"lubed-for-life" mounted bearings, thinking the lubed-for-life bearings will deliver the same life — without lubrication — as bearings that
currently require periodic lubrication. The truth is it depends on many factors, and only a detailed review of the application and testing will provide a more accurate answer.
In this century’s complex, ever-
changing world of manufacturing,
such capabilities as hardware and software expertise, effective location and distribution, business savvy and
yes, even luck, are some of the
cardinal requirements for running
a successful business.
In 1991, Needelman and Zaretsky presented a set of empirically
derived equations for bearing fatigue life (adjustment) factors (LFs) as a function of oil filter ratings.
Engineers typically learn that the bearing L10 life can be estimated using the so called “C/P method” — or the “basic rating life” of
the bearing, a method rooted in the 1940s. Major developments have since led to the “modified rating life,” released in ISO 281:2007,
which includes the aiso life modification factor. In this paper a succession of equations used for bearing life ratings are reviewed, and
current bearing life rating practices are discussed in detail. It is shown that — despite the introduction more than 30 years ago of
the adjustment factor of the basic rating life, and the standardization in 2007 of the aiso modification factor — use of these improved
calculation methods are not practiced by all engineers. Indeed — many continue referring to the old model as a way of seeking
compliance with existing, established practices.
Columnist Brian Langenberg provides a current outlook update, key findings
from a recent energy sector conference, and takes another look at education and employment.
The 8th International CTI Symposium on Automotive Transmissions, HEV and EV Drives took place in Rochester, Michigan from May 12-15. The event kicked off with its popular introductory seminar "Basics and Practice of Automotive Transmissions."