shaft coaxial hole are determined by torque requirements and material constraints the only important relative dimension is the interior diameter of the input shaft compared to the exterior dimension of the output shaft the amount of clearance between these two parts will influence the amount of axial misalignment capable of this device in a slightly different embodiment the output shaft 8 can be a shape other than a cylindrical shaft cross sectional geometry of the output shaft 8 can have a large effect on maximum transmittable torque when a non circular cross section shaft is used the flexible coupling 10 should possess a mating shape as the definition of its axial hole that accepts the input shaft for instance if the output shaft possessed an extruded square shape then the flexible coupling will be a cylindrical shape on the outside with a square co axial hole through the inside therefore mating with the output shaft whereas the primary embodiment transfers torque from flexible coupling 10 to output shaft 8 primarily by friction this embodiment transfers torque from flexible coupling 10 to output shaft 8 primarily by the flexible coupling 39 s 10 resistance to detrimental deformation maximum permissible torque of this embodiment may increase with cross sections possessing sharp angles triangle star square torx u2122 the torque limit will also increase with a flexible coupling 10 constructed of a higher durometer elastomer in this embodiment as in the primary torque is transmitted.