Abstract: A movable table 1 which rests on a mechanism with two upper parts 3 and two lower parts 4, situated on a fixed counter table 2 under which there is an electromagnet 6, which attracts a counter-weight 5 joined by way of bars 7 to a central ball-and-socket joint of an articulated safety mechanism in such a way that when the electromagnet 6 is disconnected the counter-weight 5 falls, the mechanism folds and the table 1 descends. Under the table 1 and the counter-weight 5, there exist some cylinders and stops 3, 11 which damp and limit the table's descent. The safety mechanism is housed in slots situated under the table 1 and on top of the counter table 2 and its central ball-and-socket joint is formed by the insertion of the lower shaft of the upper part of the mechanism in an upper half tube of the lower piece of the same mechanism.