SLIDING-WEDGE BREECH LOCK MECHANISM

A large-caliber gun has a breech support, a breech block movable relative thereto between open and closed positions, and a shaft centered on an axis and rotatable therabout in the support. Link mechanism connects the shaft and the breech block for angularly displacing the shaft between first and second positions respectively corresponding to the open and closed breech positions. A crank is fixed on the shaft. A lever pivotal about the axis between first and second positions has an abutment engageable angularly in only one direction with the crank. The shaft and crank are angularly displaceable independently of the lever. The lever can be pivoted from its second to its first position to similarly pivot the crank and shaft and displace the breech block into the open position. A spring-loaded biasing unit is connected between the lever and the crank and urges the crank angularly back against the abutment of the lever. Thus when the crank and shaft are moved by gun recoil from their second to their first position the biasing means is stressed, while the lever remains in its first position.