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In this special news section, the editors of Power Transmission Engineering have gathered the latest product news
and information from the gears and gear drives sector.
American Bearing Manufacturers Association (ABMA) Standard 9 and ISO 281 give equations for calculating
the basic dynamic radial load rating for ball bearings. These equations are based on a number of assumptions, many
of which are not valid for thin-section bearings. (Thin-section bearings are described in ABMA standard 26.2.)
Nevertheless, many thin-section bearing catalogs report load ratings based on these equations. Kaydon has developed a new method for calculating the dynamic radial load rating for thin-section ball bearings. The new method uses the contact stress and the number of stress-cycles-per-revolution to calculate the capacity. The new numbers are based on five years of actual test results. These equations can also be used to calculate the dynamic radial load rating for four-point contact ball bearings, which are not covered in ABMA standard 9 or ISO 281.
Suggesting a bicycle is environmentally
friendly is stating the obvious. But
the Copenhagen Wheel, unveiled at the
2009 COP15 United Nations Climate
Conference, is taking green technology
and cycling in a new direction.
During the qualification campaign of the NIRSpec (near-infrared spectrometer) instrument mechanism, the actuator could not achieve the expected lifetime that had been extended during the development phase. The initial design could not be adapted to the requested number of revolutions during that phase. Consequently the actuator needed to be modified so that the function of the mechanism would not be
endangered or, by extension, the overall function of the NIRSpec instrument. The modification included a
change of the overall actuator design—internal dimensions, tolerances, materials, lubrication and assembly
process—while keeping the interface to the mechanism, mass and function.
Despite posting its slowest quarter
since early 2007, AWEA remains
optimistic that the wind industry can
and will work successfully with the
revolving doors in Washington.
One of the driving forces behind the industrial revolution was the invention—more than a century ago—of the electric motor. Its widespread use for all kinds of mechanical motion has made life simpler and has ultimately aided the advancement of humankind.
And the advent of the inverter that facilitated speed and torque control of AC motors has propelled the use of electric motors to new realms that were inconceivable just a mere 30 years ago. Advances in power semiconductors—along with digital controls—have enabled realization of motor drives that are robust and can control position and speed to a high degree of precision. The use of AC motor drives has also resulted in energy savings and improved system efficiency. This paper reviews the development and application of inverter technology to AC motor drives and presents a vision for motor drive technology.