Current challenges for today’s industry are an increase in gear ratio in one stage, an increase in load capacity as well as an increase in efficiency compared to standard gears. The standard tooth profile for cylindrical gears is an involute. This tooth profile has certain limits for external gearings regarding its geometry, e.g., undercutting and a small radius of curvature near the base circle. Special gearings overcome these limits and offer an enormous potential in gear design through their adapted profile geometries. New manufacturing possibilities for gears, such as additive manufacturing or 5‑axis milling, mean that special gears can also be produced economically.In comparison to involute gears the description of non-involute gears is often not standardized and parameters describing the geometry are not commonly defined. Thus, it is not possible to adequately determine the corresponding properties. One of these special tooth profiles is the eccentric cycloid gearing (EC gearing), in which a circular profile rolls with a profile of a trochoid equidistant. This flank geometry can provide advantages over the standard involute in certain applications.This study introduces a geometric description of the EC gearing, which is based on a defined set of parameters. Besides the geometrical parameters, parameters describing the characteristics of the gearing are proposed in accordance with the description of involute gears. This parametric description of the EC gearing enables an analytical determination of the flank, the contact geometry and load-free characteristics. With the parametric description shown and the variation of the geometry possible with it, gearings suitable for practical applications can be generated.

Gearboxes are essential in mechanical drive trains for power transmission. A low noise emission and thus an optimized excitation behavior is a substantial design objective for many applications in terms of comfort and operational safety. There exist numerous processes for manufacturing gears, which all show different properties in relation to the process variables and, therefore, differences in the resulting accuracy and quality of the gear flank. In this paper, the influence of three different manufacturing processes for hard finishing—continuous generating grinding, polish grinding and gear skiving—on the surface structure of gear flanks and the excitation behavior is investigated experimentally and analyzed by the application force level. A tactile scanning of the gear flanks determines the flank surface structure and the deviations from the desired geometry. A torsional acceleration measurement during speed ramp-ups at different load levels is used to analyze the excitation of the gears. The results show only a minor influence of the surface structure on the application force level. The excitation behavior is dominated by the influence of the flank modification and its deviation from the design values.