Coupling for the transmission of the torque between a driving shaft and a driven shaft , comprising a first coupling element developing according to a first longitudinal axis (X) between a first end and a second end juxtaposed to said first end , said second end defining an end surface orthogonal to said first longitudinal axis (X) and delimiting said first coupling element and an outer cylindrical surface coaxial to said first longitudinal axis (X) and configured to be coupled to a bearing along a first portion of said first longitudinal axis (X); said coupling comprising coupling means belonging to said second end for transmitting the torque between said first coupling element and said driving shaft ; said coupling means comprising one or more recesses defined on said outer cylindrical surface and developing according to said first longitudinal axis (X) from said end surface towards said first end for at least one part of said first portion; said first end being provided with first rotational constraint means for the connection to said driven shaft so that said first longitudinal axis (X) is coaxial to the axis of said driven shaft , and comprising a second coupling element developed according to a second longitudinal axis (Y) between: - a first end provided with second rotational constraint means for the connection to said driving shaft in such a way that said second longitudinal axis (Y) is coaxial to the axis of said driving shaft ; - a second end juxtaposed to said first end , provided with one or more projecting bodies projecting from said second coupling element in the direction of said second longitudinal axis (Y), each of which can be conjugated to a corresponding recess of said plurality of recesses to rotatably constrain said second coupling element to said first coupling element when said first coupling element and said second coupling element are arranged with the respective longitudinal axis (X, Y) coaxial, said second rotational constraint means comprising a through hole , coaxial to said second longitudinal axis (Y) and suitable to receive said driving shaft , and connection means arranged in said through hole for transmitting the torque between said driving shaft and said through hole , characterised in that said connection means comprise a seat for a tab , extending over the entire length of said second coupling element according to the direction of said second longitudinal axis (Y) and along one of said one or more projecting bodies . - a first end provided with second rotational constraint means for the connection to said driving shaft in such a way that said second longitudinal axis (Y) is coaxial to the axis of said driving shaft ; - a second end juxtaposed to said first end , provided with one or more projecting bodies projecting from said second coupling element in the direction of said second longitudinal axis (Y), each of which can be conjugated to a corresponding recess of said plurality of recesses to rotatably constrain said second coupling element to said first coupling element when said first coupling element and said second coupling element are arranged with the respective longitudinal axis (X, Y) coaxial, <EOS>