Abstract: A device for controlling the relative vertical movements between the bridge and the feet of a marine platform, including racks cut in uprights fixed to the feet, and locomotor units each comprising a frame equipped with pinions driven in rotation by motors and meshing with the racks. Each locomotor unit frame is attached by an articulation to a connecting rod which extends along the upright, and by a separate articulation to the bridge, and is associated with a mechanism for balancing the overturning torque set up by the force which the connecting rod transmits. The device is intended for a platform for the drilling of oil wells.