The tabletop is split into two half-sections that can be moved apart or towards each other. Pairs of swing levers (3) mounted on a coupling rod (2) move at least one of the tabletop half-sections so that a plate insert (11) normally lying beneath the centre of the tabletop comes to rest in a position between the two tabletop half-sections after they have been moved apart. A positioning rod (1) acting as a joint linked to one of the tabletop half-sections passes through a hole in a tab on the coupling rod. When the tabletop half-sections are resting against each other the positioning rod rests on a stationary guide (13) and its free end has a first fixture that can be fitted into the tab.
