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The improvement of the energy efficiency of industrial gear motors and gearboxes is a
common problem for many gear unit manufacturers and end-users. As is typical of other
mechanical components, the radial lip seals used in such units generate friction and heat,
thus contributing to energy losses of mechanical systems. There exist today simulation
tools that are already helping improve the efficiency of mechanical systems — but accurate models for seal frictional losses need to be developed. In this paper SKF presents an engineering model for radial lip seal friction based on a physical approach.
A four-point contact ball bearing makes it easy to simplify
machine designs that combine radial, thrust and moment
loads, because it can handle all three simultaneously. They
are primarily used for slow-to-moderate-speed applications,
or where oscillatory movement is predominant.
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.
At SKF, we believe in the longterm
development of the U.S.
industrial economy. The reindustrialization
is supported by a strong
university-based research network,
a competitive workforce and energy
supply from domestic energy resources.
However, there are still challenges,
particularly regarding the availability
of skilled labor. Business, education
and governments have a responsibility
to work together to ensure this is not
the bottleneck in U.S. industrial development. I am particularly pleased with and support the work the National Association of Manufacturers is doing in this area.