Patent ID: 8641539

Claim:
A coupling device for transmitting torque comprising: a first shaft and a second shaft, each of the first shaft and the second shaft having a respective longitudinal axis and an end, with the ends of the first and second shafts being couplable to each other; a male element on the end of the first shaft, wherein the male element includes a portion of the end of the first shaft having, in a cross-section transverse to the longitudinal axis of the first shaft, a generally polygonal outer shape, and at least one part having an inner opening with a generally polygonal inner shape that is complementary in shape to the generally polygonal outer shape of the portion of the end of the first shaft, wherein the at least one part is slidingly mounted on the generally polygonal outer shape of the end of the first shaft, the inner opening of the at least one part is larger than the generally polygonal outer shape of the portion of the end of the first shaft so that a first functional play is provided between straight sides of the generally polygonal inner opening of the at least one part and straight sides of generally polygonal outer shape of the portion of the end of the first shaft, and the at least one part includes a polygonal outer shape; and a female element on the end of the second shaft, wherein the female element is tubular at the end of the second shaft and has, in a cross-section transverse to the longitudinal axis of the second shaft, a polygonal inner shape complementary to the polygonal outer shape of the at least one part, and the polygonal inner shape of the fubular female element is larger than the polygonal outer shape of the at least one part so that a second functional play is provided between straight sides of the inner shape of the tubular female part and straight sides of the polygonal outer shape of the at least one part, whereby, when the male element is inserted into and coupled to the female element and one of the first and second shafts is driven in rotation to transmit torques to the other of the first and second shafts, if the longitudinal axes of the first and second shafts are not coaxial, the first shaft swivels with respect to the second shaft.