Bill Bradley: AGMATech

Beyond having up-to-date information on gear design and application, today’s gear engineer needs knowledge of all the components that are required in a gearbox.


In past columns, geared products have been discussed as to how they relate to the development and refinement of gearing standards to supply designers with reliable tools for today’s requirements. However, the design of a complete gearbox for a power transmission system requires knowledge of all its components. The design of such items as bearings, shafts, and housing structures can be as critical–or more critical–than the design of the gears.

The type bearings that support the gears and shafts, as an example, need to be selected and sized to reliability provide a operating life that will equal the design life of the gears and other components within the gearbox. But there is a problem in trying to equate gear life and bearing life, as the methods for determining rating, life, and reliability are not equivalent. The underlying methods, based on similar principals, have been developed with different definitions of “life.” Therefore, gearbox standards have traditionally contained methods of applying bearing ratings.

Standards for Gearbox Design
AGMA gearbox and component standards that have included topics such as bearing selection, drive components, assembly requirements, thermal rating, lubrication, and application information are:

  • Studying and understanding some of the newer bearing rating practices used by manufacturers, such as ISO and DIN281-4 calculations;
  • Participating in the committees that are revising all the AGMA standards that have been listed in this column; and
  • Attending conferences where gearbox bearing application papers are presented, such as the AGMA 2005 Fall Technical Meeting this October in Detroit at GEAR EXPO.
    It’s important to understand the specifics of bearing application standards so that you can benefit from their strengths and know their weaknesses. Detailed information on all of the subjects discussed is provided on the AGMA Web site []. Send e-mail to