Abstract: A coupling includes a driving disk connected to a driving shaft and rotatable about a driving axis. An engagement face of the driving disk includes a predetermined number of at least three driving teeth that are distributed azimuthally on the engagement face of the driving disk along a circle concentric to the driving axis. A driven disk connected to a driven shaft and rotatable about a driven axis has an engagement face including the predetermined number of driven teeth azimuthally distributed along a circle concentric to the driven axis. At least one of the driving shaft and the driven shaft possesses translational freedom or angular freedom of motion with respect to the other so that when the driving teeth of the driving disk engage the driven teeth, the driving axis and the driven axis are self-aligned.