A coupling arrangement for coupling together rail vehicles such as railway carriages and locomotives, consisting of a coupling head comprising a coupling housing (1) joined to the rail vehicle and having an active coupling device in the form of a plunger (2) movable between an outer and an inner position and designed to co-operate with a similar plunger in a corresponding coupling head when two coupling heads are coupled together, the plungers (2) being movable in directions that are substantially perpendicular to the longitudinal directions of the coupling heads and can be released at uncoupling. A locking device (7) is provided in the coupling arrangement and comprises a locking member (7.5) arranged to be brought into contact with the plunger (2) when this is in its outer position and to prevent the plunger (2) being displaced from this position.