Door locking mechanism

Abstract

A locking mechanism to be applied to an inactive door of a set of active and inactive double doors coordinated so that the inactive door closes first relative to a frame followed by the closing of the active door. Adjustable drive means is employed capable of either lengthwise contraction upon the application of a force between first and second separated locations on the adjustable drive means exceeding a threshold value, or linear movement without substantial contraction upon the application of a force less than the threshold value. A door-lock actuating element is coupled to the adjustable drive means at the first location. A door-locking element is coupled to the adjustable drive means at the second location. The adjustable drive means, the door-lock actuating element, and the door-locking element are supported at an upper or lower corner of the inactive door. The door-lock actuating element projects into the closing path of the active door to operate the door-lock actuating element and the adjustable drive means to drive forcibly the door-locking element into a locking engagement when the drive means is subjected to less than the threshold force value. The adjustable drive means contracts in response to an obstruction which prevents the door-locking element from locking the door. A fire shield envelopes many of the operating components to prolong the integrity of the locking mechanism.