Abstract: A dual concentric shaft coupling arrangement is provided with both inner and outer rotatable assemblies. An inner assembly comprises an inner rotatable driving member, an inner rotatable driven member and an inner rotatable intermediate member that is connected therebetween. An outer assembly comprises an outer rotatable driving member, an outer rotatable driven member and an outer rotatable intermediate member connected therebetween. Both the inner and outer rotatable intermediate members comprise first and second rigid portions which are connectable to the associated driving and driven members, respectively. Between the first and second rigid portions, a compliant portion is connected for the purpose of transmitting torque between the first and second rigid portions and, consequently, between the driving and driven members. Spline arrangements are also provided in a non-contact association with each other at low magnitudes of torque.

Abstract: A shaft coupling apparatus connects first and second rotatable members by a compliant connecting component disposed radially between portions of the first and second rotatable members. A spline arrangement is also provided for the purpose of transmitting torque between the first and second rotatable members when the magnitude of torque between these members exceeds a predefined magnitude. The spline arrangement and the compliant connecting component are disposed in axial alignment for the purpose of permitting a degree of articulation to occur between the first and second rotatable members. When transmitting torque is below the predefined value, all of the torque is transmitted from the first rotatable member to the second rotatable member through the compliant connecting component which can be any resilient material, such as an elastomeric material.