Locking mechanism for a storage cabinet

A storage cabinet assembly comprising a cabinet having side walls, a rear wall and a front frame formed with openings therein for the passage of at least two sliding drawers arranged one above the other to slide through said openings from shut positions within said cabinet to projecting open positions, at least two drawers mounted in said cabinet to slide between said shut and open positions, each said drawer having side walls and a front wall, vertical guide means fixed inside one side wall of said cabinet and extending over the adjacent side walls of said drawers, an upright locking bar displaceable in said guide means longitudinally of itself between upper and lower positions, one of which is a drawer-locking position and the other a drawer-releasing position, locking means on said locking bar and means on said adjacent side walls of said drawers cooperating with said locking means to lock each drawer only when in its shut position and when said locking bar is in its drawer-locking position, locking bar actuating means on each drawer for displacing said locking bar from its drawer-releasing position to its drawer-locking position during the initial part of the opening of the drawer to lock each remaining drawer shut, a spring having one end fixed with respect to said cabinet, means operatively connecting the other end of said spring to said locking bar whereby when said locking bar is moved from the drawer-releasing position to the drawer-locking position said spring passes through an over-centre position from a first state in which it ends to hold the locking bar in the drawer-releasing position to a second state in which is retains the locking bar in the drawer locking position, said means operatively connecting said other end of said spring to said locking bar comprising a mechanism which includes a lever arm, said other end of said spring being fixed to said lever arm at a point which undergoes augmented movement relatively to the movement of said locking bar during the displacement of said locking bar, said locking bar including a line of gear teeth thereon, said locking mechanism including a pinion pivoted about an axis fixed with respect to said cabinet and having its teeth engaged with said teeth on said locking bar, said lever arm being fixed to said pinion and the radius at which said point is located with respect to said axis being greater than the radius of said pinion, and further cooperating means on each said side wall of said drawers for returning said locking bar to its drawer-releasing position and said spring to its first state when a drawer is returned from its open position to its shut position.