Carlos Wink (Ph.D., Master's degree mechanical engineering with gear design focus — University of Campinas, Brazil; B.S. mechanical engineering — Santa Cecilia, Brazil.) is a recognized expert in gear technology and power transfer,
with extensive and global experience in developing mechanical power transfer
products, such as automotive and commercial vehicle transmissions, gearboxes, rotary
actuators for aerospace applications, progressive differentials, and gear pumps.
As an engineering manager for Eaton Corp.'s Center of Excellence for components, he leads two teams of experienced engineers — one based here in the states, the other
internationally. During his more than 25 years with Eaton, Wink has held positions in both manufacturing and product engineering, and has been instrumental in successfully
bringing products from a blank sheet of paper into production. His technical expertise
has helped to significantly elevate Eaton's technical capability globally by introducing
key advanced modeling techniques and tools and standardized engineering processes. A
founder and leader of Eaton's Gear Community of Practice, Wink also guides Eaton's
participation in The Ohio State University GearLab, AGMA membership, and SAE L. Ray
Buckendale Lecture Committee. The author of a dozen technical papers, Wink is also
the inventor of two patents and serves as a reviewer for three internationally renowned
A best practice in gear design is to limit the amount of backlash to a minimum value needed to accommodate
manufacturing tolerances, misalignments, and deflections, in order to prevent the non-driving side of the teeth to make contact and rattle. Industry standards, such as ANSI/AGMA 2002 and DIN3967, provide reference values of minimum backlash to be used in the gear design. However, increased customers' expectations in vehicle noise eduction have pushed backlash and allowable manufacturing tolerances to even lower limits. This is especially true in the truck market, where engines are quieter because they run at lower speeds to improve fuel economy, but they quite often run
at high torsional vibration levels. Furthermore, gear and shaft arrangements in truck transmissions have become more complex due to increased number of speeds and to improve efficiency. Determining the minimum amount of backlash is quite a challenge. This paper presents an investigation of minimum backlash values of helical gear teeth applied to a light-duty pickup truck transmission. An analytical model was developed to calculate backlash limits of each gear pair when not transmitting load, and thus susceptible to generate rattle noise, through different transmission power paths.
A statistical approach (Monte Carlo) was used since a significant number of factors affect backlash, such as tooth
thickness variation; center distance variation; lead; runout and pitch variations; bearing clearances; spline clearances; and shaft deflections and misalignments. Analytical results identified the critical gear pair, and power path, which was confirmed experimentally on a transmission. The approach presented in this paper can be useful to design gear pairs
with a minimum amount of backlash, to prevent double flank contact and to help reduce rattle noise to lowest levels.