Abstract: A shaft coupling which can prevent trransmission of side loads in the event of angular or parallel misalignment of end-to-end shafts and which can also provide non-destructible overload protection. A pair of independent translatable devices spaced apart along the axis of the coupling, and set in planes at right angles to the axis and to each other can translate independently to permit free nutating motion of an intermediate torque-transmitting coupling member. Spring loaded balls on the ends of the independent devices decouple the shafts from each other in the event of overload. Embodiments can achieve all of the above with virtually zero back lash.