Abstract: An arrangement for locking slot wedges retaining the winding of an electric machine against displacement thereof within the longitudinal slots of the magnetic core. The locking arrangement is disposed in the end portions of the slot and comprises locking wedges in contact with the extreme slot wedges and the locking wedges have teeth on the surfaces parallel to the bottom of the longitudinal slot. Stop collars are disposed at the intersection of the longitudinal slots and extreme radial ventilating ducts and embrace the locking wedges within a tooth portion thereof. Each tooth is defined by an inclined surface facing the central portion of the longitudinal slot from the ends thereof and a surface perpendicular to the axis of the core. The stop collars are shaped congruent to the locking wedge within a tooth portion thereof and are spaced from the lateral sides thereof.