Device for handling a structure that is being lifted or lowered

A device for operating a structure by raising and lowering the structure relative to a support, by means of motorised pinions (A,B) integral with said structure, meshing into a fixed vertical rack (C) integral with said support, said device including a rack (C) cut on both sides (12,22), sandwiched between two leading pinions (A,B) with horizontal axes and arranged in substantially in the same horizontal plane, driven into opposite directions by a motorised system (2), wherein an outlet shaft (3) of said motorised system (2) transmits the driving motion to a primary reducing system (4) and an outlet shaft (5) of the reducing system (4) serves as an inlet shaft of a secondary reducing gear (6) of a planetary differential type including a solar pinion (7), satellite pinions (8) and an outer ring (14), wherein a satellite holder (9) of said secondary differential reducing gear (6) drives one of said pinions (A), on one of the sides (12) of said double rack (C), and the outer ring (14) of said planetary reducing gear (6) drives by a mechanical linking means (18, 24), a toothed wheel (17) in charge in turn of driving the second pinion (B) on the other side (22) of said double rack (C).