Abstract: A platform trestle or device for use in the construction of stages, tribunes and the like, including a rectangular frame supporting a platform, and operatively releasable support legs which can be inserted and clamped into place in mounting spaces within mounting elements which are fixedly arranged at the corners of the rectangular frame. In order to facilitate the attachment of the support legs to the mounting elements during assembly of the platform device, and to increase the seating stability of the support legs, each of the mounting spaces is fashioned as a wedge-shaped chamber which tapers toward the platform. Each wedge chamber is defined by a pair of adjoining vertical sides and pair of adjoining inclined sides, with each of the inclined sides being inclined with respect to its adjoining inclined side and at least one of the vertical sides.