Mechanical subassembly for a chair having a base element, a back element and a seat element being able to be articulated to the mechanical subassembly, - the mechanical subassembly comprising a housing portion which can be connected to the base element and at least one connection member (V1, V2) which can be connected to the seat element or to the back element, - the connection member (V1, V2) being pivotably articulated to the housing portion, - the mechanical subassembly comprising at least a first pair of flange means, - the flange means being connected to the housing portion, and - the first flange means and the second flange means of the first pair being orientated with respect to each other in such a manner that they are located with their geometric axes on a common longitudinal axis, characterised in that - the connection member (V1, V2) being constructed as a curved member, - the curved member comprising a connection element (VE1, VE2) and a pair of counter-flange means, - the counter-flange means being connected to each other by means of the connection element (VE1, VE2), - the first counter-flange means and the second counter-flange means being orientated with respect to each other in such a manner that they are located with their geometric axes on a common longitudinal axis, - the flange means and the counter-flange means being adapted to each other in terms of their construction and arrangement in space in such a manner that, when the longitudinal axes are parallel, they can be coupled to each other in an assembly direction which extends orthogonally with respect to the longitudinal axes in such a manner that the longitudinal axes are located in the coupled position on a common rotation axis and that the curved member with the counter-flange means, after pivoting with respect to the housing portion about the rotation axis through a pivot angle of at least 60 and a maximum of 120 through an additional pivot angle of at least 30 in all directions orthogonal with respect to the rotation axis, is retained on the housing portion in such a manner that the two longitudinal axes remain on the rotation axis in the event of tensile loads and pressure loads in the mentioned orthogonal directions and thus couple the housing portion and the curved member to each other in a pivoting manner about the rotation axis. - the mechanical subassembly comprising a housing portion which can be connected to the base element and at least one connection member (V1, V2) which can be connected to the seat element or to the back element, - the connection member (V1, V2) being pivotably articulated to the housing portion, - the mechanical subassembly comprising at least a first pair of flange means, - the flange means being connected to the housing portion, and - the first flange means and the second flange means of the first pair being orientated with respect to each other in such a manner that they are located with their geometric axes on a common longitudinal axis, - the connection member (V1, V2) being constructed as a curved member, - the curved member comprising a connection element (VE1, VE2) and a pair of counter-flange means, - the counter-flange means being connected to each other by means of the connection element (VE1, VE2), - the first counter-flange means and the second counter-flange means being orientated with respect to each other in such a manner that they are located with their geometric axes on a common longitudinal axis, - the flange means and the counter-flange means being adapted to each other in terms of their construction and arrangement in space in such a manner that, when the longitudinal axes are parallel, they can be coupled to each other in an assembly direction which extends orthogonally with respect to the longitudinal axes in such a manner that the longitudinal axes are located in the coupled position on a common rotation axis and that the curved member with the counter-flange means, after pivoting with respect to the housing portion about the rotation axis through a pivot angle of at least 60 and a maximum of 120 through an additional pivot angle of at least 30 in all directions orthogonal with respect to the rotation axis, is retained on the housing portion in such a manner that the two longitudinal axes remain on the rotation axis in the event of tensile loads and pressure loads in the mentioned orthogonal directions and thus couple the housing portion and the curved member to each other in a pivoting manner about the rotation axis.