Abstract: A friction coupling for locking a shaft relative to a hub is disclosed. The friction coupling includes a radially deformable inner sleeve, a radially deformable outer sleeve, an annular piston which is axially movable relative to the inner sleeve and the outer sleeve, the annular piston having a conical surface, which cooperates with the inner sleeve and/or the outer sleeve and which is arranged to deform the inner sleeve and/or the outer sleeve when the annular piston is moved relative to the inner sleeve and the outer sleeve so as to provide the locking. In at least one embodiment, the friction coupling further includes at least one actuating device to produce a movement of the annular piston for locking the friction coupling, and at least one deactuating device to produce a movement of the annular piston for unlocking the friction coupling. The at least one actuating and deactuating devices are located, seen in the axial direction, on the same side of the annular piston.