A lock mechanism comprising: a housing (12, 28); and a slide bar mounted in said housing (12, 28) for translational movement between (a) a first position and (b) a second position; characterized in that the lock mechanism further comprises: a first biasing means for exerting a bias force on said slide bar urging it toward the second position thereof; a latch mounted in said housing (12, 28) and movable between (a) a first position in which said latch holds said slide bar in the first position thereof when moved thereto, and (b) a second position in which said latch releases said slide bar permitting it to move to the second position thereof under the force exerted by said first biasing means; second biasing means for exerting a bias force on said latch urging it toward the first position thereof; a first cam rotatably mounted in said housing (12, 28) and having a lobe engagable with said latch for, upon rotation of said first cam, urging said latch to the second position thereby releasing said slide bar to move to the second position; and manual operating means (18, 20) comprising a knob operable from the exterior of said housing (12, 28) and a knob slider, said manual operating means (18, 20) being manually movable in a first direction, which causes the slide bar to move from the second position to the first position, and in an opposite direction, which does not cause the slide bar to move to the second position. a housing (12, 28); and a slide bar mounted in said housing (12, 28) for translational movement between (a) a first position and (b) a second position; characterized in that the lock mechanism further comprises: a first biasing means for exerting a bias force on said slide bar urging it toward the second position thereof; a latch mounted in said housing (12, 28) and movable between (a) a first position in which said latch holds said slide bar in the first position thereof when moved thereto, and (b) a second position in which said latch releases said slide bar permitting it to move to the second position thereof under the force exerted by said first biasing means; second biasing means for exerting a bias force on said latch urging it toward the first position thereof; a first cam rotatably mounted in said housing (12, 28) and having a lobe engagable with said latch for, upon rotation of said first cam, urging said latch to the second position thereby releasing said slide bar to move to the second position; and manual operating means (18, 20) comprising a knob operable from the exterior of said housing (12, 28) and a knob slider, said manual operating means (18, 20) being manually movable in a first direction, which causes the slide bar to move from the second position to the first position, and in an opposite direction, which does not cause the slide bar to move to the second position. a first biasing means for exerting a bias force on said slide bar urging it toward the second position thereof; a latch mounted in said housing (12, 28) and movable between (a) a first position in which said latch holds said slide bar in the first position thereof when moved thereto, and (b) a second position in which said latch releases said slide bar permitting it to move to the second position thereof under the force exerted by said first biasing means; second biasing means for exerting a bias force on said latch urging it toward the first position thereof; a first cam rotatably mounted in said housing (12, 28) and having a lobe engagable with said latch for, upon rotation of said first cam, urging said latch to the second position thereby releasing said slide bar to move to the second position; and manual operating means (18, 20) comprising a knob operable from the exterior of said housing (12, 28) and a knob slider, said manual operating means (18, 20) being manually movable in a first direction, which causes the slide bar to move from the second position to the first position, and in an opposite direction, which does not cause the slide bar to move to the second position.