Abstract: A lifting unit, comprising a frame for supporting a motorized winch, at least one first tackle and one second tackle, the first tackle being interposed between the second tackle and the winch, each tackle being provided with two blocks, a fixed one and a movable one, and each comprising at least one pulley, and a flexible element, with a first end connected to the winch and wound around the pulleys, to form at least one initial loop around the first tackle, an outgoing portion from the first tackle to the second tackle, at least one intermediate loop around the second tackle, a return portion from the second tackle to the first tackle, and at least one end loop around the first tackle, the second end of the flexible element being connected to the frame, and a temporarily locking element for locking sliding of the flexible element.