A shaft coupling comprising, a first shaft having a first end (1-1) and a second end (1-2), and a first bearing being arranged in the vicinity of the first end (1-1), and a second shaft having a first end (2-1) and a second end (2-2), and a second bearing being arranged in the vicinity of the second end (2-2), and said first shaft and second shaft are coaxially arranged so that the second end (1-2) of the first shaft is against the first end (2-1) of the second shaft , in addition to said first bearing and second bearing , to support the first shaft and second shaft , the shaft coupling comprises only one third bearing arranged in the vicinity of the coupling point of the first shaft and second shaft , and the shaft coupling further comprises a coupler which receives the second end (1-2) of the first shaft and the first end (2-1) of the second shaft and non-rotatably connects these to each other in order to transmit power between said first shaft and second shaft , characterised in that there is, on an end surface of the second end (1-2) of the first shaft , a recess , and that there is a protrusion protruding from the end surface of the first end (2-1) of the second shaft , said protrusion is an axial protrusion being part of the second shaft , and said recess receives said protrusion in direct contact so that a side surface of the protrusion and a side surface of the recess are set against each other, and in that the side surface of the protrusion or the side surface of the recess , or both of said mating surfaces, is/are shaped curved in the axial direction of the first shaft and second shaft . a first shaft having a first end (1-1) and a second end (1-2), and a first bearing being arranged in the vicinity of the first end (1-1), and a second shaft having a first end (2-1) and a second end (2-2), and a second bearing being arranged in the vicinity of the second end (2-2), and said first shaft and second shaft are coaxially arranged so that the second end (1-2) of the first shaft is against the first end (2-1) of the second shaft , in addition to said first bearing and second bearing , to support the first shaft and second shaft , the shaft coupling comprises only one third bearing arranged in the vicinity of the coupling point of the first shaft and second shaft , and the shaft coupling further comprises a coupler which receives the second end (1-2) of the first shaft and the first end (2-1) of the second shaft and non-rotatably connects these to each other in order to transmit power between said first shaft and second shaft , characterised in that there is, on an end surface of the second end (1-2) of the first shaft , a recess , and that there is a protrusion protruding from the end surface of the first end (2-1) of the second shaft , said protrusion is an axial protrusion being part of the second shaft , and said recess receives said protrusion in direct contact so that a side surface of the protrusion and a side surface of the recess are set against each other, and in that the side surface of the protrusion or the side surface of the recess , or both of said mating surfaces, is/are shaped curved in the axial direction of the first shaft and second shaft . <EOS>