area at 120 u00b0 the landing of the upper cargo container has been accomplished referring now to fig1 and as mentioned hereinabove body 132 is formed with a plurality of skirts 144 about its lower edges see fig1 skirts 144 interact with chamfered edges 158 of the opening in the corner fitting as such mechanism 102 can be inserted into the opening until skirts 144 contact chamfered edges 158 it will be appreciated that this contact occurs on all four sides of mechanism 102 thus limiting any movement of mechanism 102 with respect to the corner fitting other than downward vertical movement to secure mechanism 102 within the corner fitting a plurality of wedges 160 are employed as shown two wedges are attached on each side of mechanism 102 via clamping screws 162 wedges 160 are preferably formed with a conical shape such that tightening of screw 162 forces the individual wedge into greater contact with the interior surface of the corner fitting thus urging mechanism 102 vertically upward while at the same time fixedly securing mechanism 102 therein fig2 shows a corner fitting of a domestic container containing the automatic lock of the present invention interacting with a retainer positioned on the floor of a well car as discussed hereinabove the retainers located on the floor of the well car penetrate and engage the inboard openings of the lower corner fittings plate 164 which supports retainer 22 typically has a thickness of approximately u00bd inch.