Mechanism for locking a door or door leaf to the floor

A locking mechanism, comprising:

• a housing member having a cavity defined therein, a peripheral wall of said cavity having a latch recess defined therein;
• a slide block received in said cavity of said housing and being slidable along a first axis;
• a latch fixed to said slide block;
• a mounting pin pivotally coupled to said slide block about a first pivot axis;
• an operating handle engaging said mounting pin;
• a bell crank lever pivotally coupled to said slide block about a second pivot axis substantially perpendicular to said first pivot axis, said bell crank having a first arm and a second arm, said first arm extending beyond said mounting pin, said second arm extending in a direction parallel with said first axis and having a hook laterally extending therefrom, said hook releasably engaging said latch recess;
• and
• a spring biasing said first arm of said bell crank lever in a direction parallel with said first axis,
• wherein said bell crank lever is arranged such than, when said mounting pin is pivoted during operation, said bell crank lever pivots and releases said hook from said latch recess, thereby permitting said slide block and said latch to move along said first axis and relative to said housing member.