Abstract: Devices for changing the slope of rows of tiers, whose bearing structures are definitively or temporarily fast, by a single elevating operation. The devices include tiers whose bearing supports are constituted by first long columns and second short columns, which, by actuation of elevating motors are alternately brought in supporting position of the tiers, the first long columns in active supporting position generating a first, more accentuated slope profile for the tiers, the second short columns, brought in active position of the tiers generating a second less accentuated slope profile.

Abstract: A mechanical system constituting a modular driving unit for the programmed displacement of a mobile structure with respect to a reference bearing plane, the structure remaining parallel to itself. The mechanical system includes a frame formed by at least two lateral sides connected together. The frame is fast with the mobile structure. There is a principal upright articulated on the frame by a first end, with the second, opposite end resting on said reference bearing plane. There is also a maneuvering jack articulated by one end on the frame and by the opposite end on the second end of upright. Maneuver of the jack allows the angular displacement of the upright. The assembly of the upright and the jack constitutes with the frame a deformable triangle.