A corner casting of the type used for lifting and moving containers is mounted to auxiliary apparatus such as a spreader for holding deckloading cargo. The corner casting is configured for actuating a crank upon the penetration of the lifting hook. When the hook penetrates at the top hole of the corner casting, a pedal pad is depressed. The pedal pad in turn is attached to a lever arm having a pivot at one end, the pedal pad at the other end and a pivotally attached spring bias rod therebetween. Upon twistlock penetration, the spring biased rod produces crank rotation at a protruding eccentric from a crank. By using the spring biased rod rotary motion can be imparted to the crank so that lifting of the spreaders effects automated container release in the case of the disclosed equalizer.