Abstract: In an electronic digital safe lock including a slide plate pivotally connected by an articulated linkage to a bolt operating lever for retracting safe door locking bolts after digital input of the electronic lock combination, a lock override is provided which includes a dial operated mechanical combination lock having a linkage pivotally interconnecting the manual combination lock bolt with the electronic lock articulated linkage of the slide plate and bolt operating lever. When the electronic lock is locked, i.e., the slide plate is immovable, the manual combination lock can be manipulated to operate the aritculated linkage to operate the bolt operating lever independent of movement of the slide plate.

Abstract: An additional locking system is provided for a combination lock. The combination lock includes a housing, a locking mechanism and a bolt in the housing movable between a first position projecting out of the housing and a second position generally withdrawn in the housing. The bolt can be moved to the second position only when the locking mechanism is in an unlocked condition. The additional locking system provides an additional lock for the bolt in the first position, and a heat responsive member prevents the additional locking system from locking the bolt until the housing is heated above a predetermined temperature. The additional locking system includes a spring with an arm thereon in the housing. The bolt includes a slot and the spring is mounted such that the arm is adjacent the slot, and the spring biases the arm toward the slot. The heat responsive member is a fuse in the housing urging the spring against the biasing to hold the arm out of the slot.