Abstract: A dynamo-electric machine provided with a retention mechanism for conductors disposed in a core slot is disclosed, wherein the mechanism comprises at least one composite wedge arrangement consisting of a first wedge having its wedge-shaped surface extending longitudinally of the slot, a second wedge similar to the first and also having its wedge-shaped surface extending longitudinally of the slot but disposed with its direction of taper opposed to that of the first wedge, there being further provided a spring member cooperating with the composite wedge arrangement, the spring member extending longitudinally of the slot and its deformation being dependent upon the relative longitudinal displacement in the slot of the first and second wedges.