Flush bolt mechanisms

For use in conjunction with a pair of swinging doors, a bolt mechanism comprising a support member having a surface adapted to be mounted essentially flush with the free edge of one of the pair of swinging doors, shaft support means extending from said support member on the side thereof opposite said surface, a first shaft slidably carried adjacent to said surface by said support means and including a latch bolt at one end thereof adapted to be extended beyond a horizontal edge of the door, spring means normally biasing said first shaft to a retracted position, a cam pivotally carried by said support member on an axis parallel to said first shaft and extending beyond the surface thereof and adapted to be engaged by the other of the swinging doors, a cam follower engaged by said cam, said cam follower being pivotally carried by said support member on an axis parallel to said surface and in a plane perpendicular to said first shaft and having a lever arm extending inward beyond said first shaft for movement about the cam follower axis, a second shaft parallel to said first shaft and pivotally carried at one end by the inward distal end of said lever arm and carried at the other end by a said first shaft so that linear movement can be imparted to said first shaft against the bias of said spring means upon generally axial movement of said second shaft in response to pivoting of said cam when engaged by the other of the swinging doors, said second shaft being carried in parallel relationship by said first shaft by a slide connection, and an override spring means normally biasing said second shaft to an extended position relative to said first shaft, the first-named spring means and said over-ride spring means having spring characteristics so that said first-named spring means can be displaced axially by a lesser load than is required to displace said override spring means.