Abstract: A mechanism (1) comprising a driving element (4) for rotationally driving a winding shaft (2) for a closing or sun-protection installation of an opening (0) and at least one spring (5) for compensating a weight of the installation. The spring (5) is mounted around the driving element (4) and is jointly associated with a sub-unit (10), which can be at least partially introduced in a unitary manner inside the shaft (2). The spring (5) includes a first end (51) kinematically linked to said driving element (4) so that the first end (51) is immobilized in rotation abut an axis of rotation (X-X?) of the shaft (2), and a second end (52) kinematically linked to the shaft (2) when the sub-unit (10) is placed inside the shaft (2) so that the second end (52) rotates about the axis of rotation (X-X?).

Abstract: The mechanism (1) comprises an element (4) for rotationally driving a winding shaft (2) for the closing screen of an opening (O) and at least one compensating spring (5) for the weight of the screen. The spring (5) is mounted around the driving element (4) and is jointly associated with a sub-unit (10) which can be at least partially introduced (F1) in a unitary manner inside the shaft (2), a first end (51) of the spring (5) being cinematically linked to said element (4) and a second end (52) thereof being able to be cinematically linked to the shaft (2) when the sub-unit (10) is placed inside the shaft (2).