System for coupling two shafts in rotation without play

A system for coupling two shafts in rotation without play, comprising:

• a driving shaft, one tubular end of which has an inner wall equipped with at least one longitudinal groove,
• a driven shaft, with a diameter (D2) smaller than an internal diameter (D1) of the tubular end of the driving shaft, the driven shaft comprising at an end a projecting cylindrical transverse pin configured to penetrate into the at least one groove and to cooperate with a longitudinal edge of said at least one groove so that the driving shaft drives the driven shaft, and
• elastic return means configured to return the pin, arranged between the driving shaft and the pin, configured to urge the pin without play against the longitudinal edge of the groove,
• the return means comprising a return spring, comprising in succession:
• a first helical attachment section having a diameter corresponding to the diameter of the driven shaft, turns of which are wound in a first orientation, and configured to be threaded around the driven shaft through the pin with a sliding or uncertain type of adjustment around said driven shaft,
• a second section comprising a wire segment configured to bear on the pin, and
• a third elastic return section, comprising at least one helical portion, extending from the second section, turns of which are wound in a second orientation opposite to the first orientation, said third section also comprising means for bearing said third section in the tubular end of the driving shaft, and being configured to elastically urge the second section to form the elastic return means that returns the pin.