More than 100 years ago, gear
manufacturers were facing
a significant challenge from
industry. The incredible advances in
industrialization and transportation that
occurred at the turn of the 20th century
resulted in incredible growth for gear
makers, but there were significant technical
issues. "The lack of process and product
standardization was a continuing
problem in all U.S. industry. The lack
of industry-wide gear standards meant
there were no standard gear tooth sizes,
ratings, quality definition or consistent
manufacturing methods" (Celebrating
100 Years of Gearing, pg. 22).
No, not that president! I mean Matt Croson, the new president
of the American Gear Manufacturers Association, who
started in June and has been busy getting to know the gear
industry and AGMA's members.
This proposed standard would not make any recommendations
regarding the required quality for any application. The
intent is to establish standard pre-finish quality classes for typical
finishing operations, which only include the inspection elements
that are important to properly evaluate pre-finish gear
quality as it applies to the finishing operation. It would be the
responsibility of the manufacturing/process engineer, quality
engineer, or other responsible individual to establish the
required pre-finish quality class for their application.
The common calculation methods according to DIN 3990 and
ISO 6336 are based on a comparison of occurring stress and
allowable stress. The influence of gear size on the load-carrying
capacity is considered with the size factors YX (tooth root bending)
and ZX (pitting), but there are further influences, which
should be considered.
In the following, major influences of gear size on the load factors
as well as on the permissible tooth root bending and contact
stress will be discussed.