Comparing Contact Stress Estimates of Some Straight Bevel Gears With ISO 10300 Standards

The pitting resistance of straight bevel gears, like other gears, is commonly assessed on the basis of the contact stress in a gear mesh. A new contact stress model for straight bevel gears is used to estimate the contact stress in some gearset designs and compared with predictions from ISO 10300 bevel gear standards. In the cases considered, the new model contact stresses defer from the ISO values in the range of 13% to 33%, with the ISO predictions generally on the higher side. These deviations appear to be somewhat high but not unreasonable because of obvious differences in the two models. The ISO standard uses the mid facewidth cone radius in its contact stress model while the new model uses the cone backend radius which is larger than the mid facewidth cone radius. Another contributing factor is that the load service factor values evaluated from ISO methods are generally higher than those of the new model values, based largely on American Gear Manufacturers Association (AGMA) methods. It should be noted that the power ratings for all the design cases studied are below 10 kW.