A summary of the testing methodsemployed and the results generated for unidirectional andreverse bending tests of very coarse andmedium pitch gear teeth is presented. Actual measured stresses were comparedwith FEM theoretical stresses and AGMA stress numbers.
The purpose of this testing was to evaluate which type hardening method would yield a gear tooth that could carry the highestloadwithoutcatastrophicbreakage failure in a single,or very low cyclic load application.This testing simulated theoutput pinion and aplanet gear for ajack-up gear driveused on oil drilling platforms. Therewere three separate tests
conducted over a period of time.
The first testwas performed staticallyon an actual 12inchcircnlarpitchpinionloadedagainst arack. Asecond statictest
utilized a half scale model of a 12CP gear tooth fillet loaded to failure in a single cycle and also cycled to failure at extremely high loads. The third test was a reverse bendingtest simulating a planet of a planetary gear used in the final reduction stage.
The last two tests were accomplished simultaneouslyfor both through hardened and carburizedtest pieces. The results
demonstrated the benefits of therelatively ductile throughhardenedgears and theirability to locally yield and dism'bute stresses without catastrophicallyfailing in this type of application.