A torque transfer coupler for a roller blind. The torque transfer coupler has a central body securable to an electric motor and includes one or more torque transfer elements engaging the interior of the blind's roller tube. The coupler includes an anti-slip member having one or more resilient portions having a rest position and a deflected position. When, in their rest positions the resilient portions have a dimension larger than the cross sectional area of the roller tube. When in their deflected positions and received within the roller tube the resilient portions engage the interior surface of the roller tube resisting the withdrawal of the torque transfer coupler, and the electric motor secured thereto, from the interior of the roller tube.

Assembling method of a pinion on a turbine axis of an internal combustion engine, wherein said pinion is made in a single piece having axial symmetry and equipped with an annular toothed part and with an axial part coaxial with said annular part and provided with a coaxial hole with a thread to screw the pinion on said axis of the turbine, wherein said thread has localized pitch variations.

A friction connecting means includes a receiving element and engagement elements. The receiving element has a pressure pocket provided with a carbon fiber composite material layer.