Theoretical and Experimental Study on Gear-Coupling Contact and Loads Considering Misalignment, Torque, and Friction Influences

A new analytic model addresses the tooth contact and induced loads of gear couplings that are affected by misalignment, torque, and friction. The contact model accounts for Hertzian, bending, and shear deformations of coupling teeth considering crown modifications. For a specified torque and shaft misalignment, the model calculates the number of teeth in contact, tooth load, stiffness, stress, deformation, and safety factors. The tooth load distribution around the circumference compares well with high fidelity finite-element/contact-mechanics analyses. Simulation time with the analytic model is orders of magnitude less. Using the local contact characteristics, the model computes coupling loads that are primarily caused by the disrupted tooth contact and sliding friction caused by axial motions. This analytic model was validated by experiments. The load amplitude depends on the misalignment, torque, and friction. At low torque, coupling motion was induced by the eccentricity between the hub and sleeve even with nearly perfect alignment. This eccentricity was caused by its self-weight. When torque was larger than a threshold, the motion amplitude was greatly reduced. This torque threshold was analytically derived and validated by experiments.