This report investigates the wear morphology on the large end of tapered rollers and the inner ring's large end rib on a planet carrier TRB from a multi-megawatt wind turbine gearbox. The literature on abrasive wear has many classifications, including 2-body abrasion, 3-body abrasion, scratches, grooving abrasion, rolling abrasion, cutting abrasion, and plowing abrasion. For this analysis, we have selected grooving abrasion, a common problem in wind turbine gearboxes and a prominent failure mode on many bearings, particularly planetary carrier bearings and planet bearings. Grooving abrasion is frequently observed on cylindrical roller bearings (CRB) and tapered roller bearings (TRB). Fitzsimmons and Clevenger conducted tests on roller end/rib wear for TRBs with contaminated gear oil, and they provided an excellent explanation of the mechanism.

This report discusses grain size and its influence on metallurgical properties including its effect on yield strength, ultimate strength, fatigue strength, and fracture toughness. Also discussed are manufacturing issues such as heat treatment, hardenability, and machinability. 

The objective of this report is to determine the origin of the phrase “profile shift.” Several technical books, technical papers, and industrial standards were reviewed for nomenclature associated with profile shift. The phrase “profile shift” translates directly to the German term “Profilverschiebung,” which originated in the last quarter of the 19th century. At first, profile shift was used to avoid undercutting pinions with small numbers of teeth. Later, it was recognized that profile shift improved the load capacity of the gear mesh and extended the service life of manufacturing tools.

The conjugacy of meshing gears is one of the most important attributes of gears because it ensures a constant velocity ratio that gives smooth, uniform transmission of motion and torque. Some of the world’s greatest gear theoreticians like Earle Buckingham, Wells Coleman, and John Colbourne laid the foundation for understanding conjugacy. Their teachings and interpretations of the law of gearing have been used by generations of gear engineers to design and manufacture gear transmissions for almost everything that is mechanically actuated. 

An overview of the incubation, nucleation and growth, and morphology of this common failure mode, along with the appropriate terminology to describe it.

The objective of this paper is to improve the methodology for determining the tooth flank temperature. Two methods are proposed for assessing scuffing risk when applying AGMA 925 for high-speed gears. Both methods provide similar results.