Numerical-experimental Analysis of Highly Crowned Spherical Gear Couplings Working at High Misalignment Angles

Spherical gear couplings are characterized by their high capacity to transfer power between rotating shafts in highly misaligned conditions. They are usually small because of space restrictions and require a high amount of longitudinal crowning, which sometimes leads to undercutting profiles. These issues have been solved recently with analytical models for the generation of tooth surfaces that consider the hob thread surface, however, they are not experimentally validated. Likewise, it has been numerically concluded that the number of teeth in contact in high misalignment conditions decreases, and thus may fail by tooth root breakage. Nevertheless, published experimental tests for such high misalignment angles are scarce. This paper presents test techniques to study highly crowned spherical gear couplings, together with a test rig design adapted to high misalignment angles. The tooth surface geometry, maximum misalignment, stiffness, and contact pattern are compared. The results demonstrate that the analytical and numerical models employed accurately represent the mechanical behavior of spherical gear couplings working at high misalignment applications.