The joint has a stationary housing section (1), a rotating housing section (2) and a locking element (4). If the locking element is fitted to the rotary joint, it prevents both rotating sections turning with respect to each other. The locking element has a weak point (4d) to facilitate its rapid removal by snapping off. A holder (6) with slit is joined to the external mantle of the stationary housing section. The upper surface of the rotating housing section incorporates a projection (8a). The locking element is joined to a horizontal arm (4a), a hook-shaped (4b) section and a link zone (4c) extending downwards from one end of the arm.
