able to operate with maximum precision even if the two machines 1a 1b are mounted in a relatively imprecise manner with respect to each other that is to say in such a way that they are not perfectly aligned in fact the drive shaft 11 and its sleeve 16 are able to compensate any shift in the mutual positions of the two machines the latter can then be moved towards and away from each other even if necessary without interrupting the sewing operations when it is not required to use a sewing machine of the type described the machine 1 can be immediately and simply divided into two independent machines one a right hand type machine and the other a left hand type machine the operations to be performed consist in simply unscrewing certain screws in particular the screws 19 which fix one end of the sleeve 16 and the screws 15 which fix the drive shaft 11 to the hubs 12 once the drive shaft 11 together with its sleeve 16 have been removed the individual sewing machines 1a 1b differ from the conventional sewing machines normally produced only on account of the presence of the bosses 9a and the hubs 12 located in the region.