<p>The present invention has in principle an unfoldable base structure with legs and a roof structure also unfoldable. It is characterized in that it comprises:
- longitudinal beams wherein mobile beams are guided and inside them end beams are coupled,
- cross beams with legs connected to a bed chassis wherein the longitudinal hollow beams are fixed,
- silage sides coupled to the bed chassis and formed by several hinged parts arranged at both sides of the stage trailer,
- vertical telescopic columns joined to the ends of the mobile beams which have other end legs. The roof structure connects with the vertical telescopic columns.</p>
