Quick-coupling assemblies of the above mentioned kind are previously known through U.S. Pat. No. 4,208,034 to Ohlsson. These couplings are especially adapted as hydraulic couplings for very high pressures and an advantage is that they can be connected and disengaged with a very simple manipulation without any tools. By the special design the couplings can be arranged in close groups, which means that the hydraulic blocks can be made considerably more compact than previously. A drawback with these couplings is however, especially if they are used for very high pressures, that they cannot freely rotate about its axis, i.e. the axis of the coupling, and therefore, in such cases where rotation can occur, the coupling must be provided with special rotation means. This however, complicates the construction and also provides a possible untightness at the same time as it raises the price of the coupling.