The Effect of Gear Set Loading on the Form of Damage to Teeth Working Surface

An analysis of cylindrical gears’ working surface after scuffing shock tests allowed for an assessment of the effect of loading conditions on the form of damage to teeth working surface. In contrast with the method of scuffing in severe conditions, where loading values are implemented gradually, a direct maximal loading – the shock loading – was used in the tests presented, not preceded by lapping the gears with a lower loading. This manner of loading considerably increases the analysed elements’ vulnerability to scuffing, allowing to judge their limit operational properties. To identify the changes and types of the teeth’s working surface damage, the following microscopy techniques were applied: scanning electron microscopy (FE-SEM) with EDS microanalyser, optical interferential profilometry (WLI), atomic force microscope (AFM), and optical microscopy. The results allowed for defining characteristic damage mechanisms and assessing the efficiency of the applied DLC coatings when it comes to resistance to scuffing in shock scuffing conditions. Tribological tests were performed by means of FZG T-12U gear test rig in a power circulating system to test cylindrical gear scuffing. The gears were made from 18CrNiMo7-6 steel and 35HGSA nano-bainitic steel and coated with W-DLC/CrN.