Support assembly for movable, rotating or sliding shafts, comprising a bearing unit adapted to receive the movable shaft, a casing and a cover for fluid sealing an opening of an internal seat of the casing; - the cover comprising an annular coupling portion that extends toward a radially external lateral surface of the casing, the annular coupling portion being provided radially on the inside with at least one pair of teeth projecting radially towards the inside of the cover and spaced circumferentially from each other; - the radially external lateral surface of the casing being provided with an annular seat for receiving the teeth of the cover, - the annular seat consisting of: an annular groove arranged axially spaced with respect to a front edge of the casing delimiting the opening and connected to a number of axial grooves equal to the number of teeth present on the cover and which interrupt radially at least part of the front edge; and in a bottom wall of the annular groove which is provided in the circumferential direction with an alternating plurality of depressions and projections, the projections being arranged circumferentially offset with respect to the axial grooves; - the annular coupling portion of the cover is provided with a plurality of radially internal projections with a convex end surface, and which engage, in sequence, with the lateral surface of the casing along a circumferential portion without axial grooves and with corresponding depressions in the annular groove of the casing; wherein the annular groove has at least one pair of mechanical stops for the at least one pair of teeth of the cover, the mechanical stops extending in a radial direction, with respect to corresponding depressions, to be flush with the lateral surface of the casing. - the cover comprising an annular coupling portion that extends toward a radially external lateral surface of the casing, the annular coupling portion being provided radially on the inside with at least one pair of teeth projecting radially towards the inside of the cover and spaced circumferentially from each other; - the radially external lateral surface of the casing being provided with an annular seat for receiving the teeth of the cover, - the annular seat consisting of: an annular groove arranged axially spaced with respect to a front edge of the casing delimiting the opening and connected to a number of axial grooves equal to the number of teeth present on the cover and which interrupt radially at least part of the front edge; and in a bottom wall of the annular groove which is provided in the circumferential direction with an alternating plurality of depressions and projections, the projections being arranged circumferentially offset with respect to the axial grooves; - the annular coupling portion of the cover is provided with a plurality of radially internal projections with a convex end surface, and which engage, in sequence, with the lateral surface of the casing along a circumferential portion without axial grooves and with corresponding depressions in the annular groove of the casing; wherein the annular groove has at least one pair of mechanical stops for the at least one pair of teeth of the cover, the mechanical stops extending in a radial direction, with respect to corresponding depressions, to be flush with the lateral surface of the casing. wherein the annular groove has at least one pair of mechanical stops for the at least one pair of teeth of the cover, the mechanical stops extending in a radial direction, with respect to corresponding depressions, to be flush with the lateral surface of the casing.