Abstract: A charge socket is provided with a charge coupling having a tubular member, which has an expandable portion and a bearing socket at one end, in which an openable notch is arranged in its lateral wall. A ferrule is clad on the tubular member and allowed to be moved along that tubular member axially. A sphere of a clamp means might be embedded in the bearing socket and permitted to rotate freely for adjustment of the angle between the clamp means and the charge coupling. When the ferrule is displaced to the position of the expandable portion of the tubular member, the tube wall of the bearing socket is forced to clamp the sphere tightly to forbid rotation thereof.