Mechanical drive device provided with a torquemeter with a phonic wheel, gearbox provided with such a mechanical drive device and aircraft

A mechanical device comprising an input pinion and a terminal pinion that are able to rotate about a rotation axis, an intermediate shaft extending longitudinally along the rotation axis from a first proximal end to a first distal end, a first mechanical rotational drive connection connecting the intermediate shaft and the input pinion, a second mechanical connection connecting the first distal end of the intermediate shaft and the terminal pinion, the mechanical device comprising a torquemeter cooperating with the intermediate shaft,

• wherein:
• the torquemeter is a torquemeter with a phonic wheel provided with a reference shaft extending longitudinally along the rotation axis from a second proximal end to a second distal end, the reference shaft being arranged at least partially inside the intermediate shaft and being coaxial to the intermediate shaft, the second distal end of the reference shaft being connected to the intermediate shaft, the torquemeter comprising at least one measuring index secured to the intermediate shaft and arranged at the first proximal end and at least one reference index secured to the reference shaft and arranged at the second proximal end;
• the intermediate shaft is coaxial with the input pinion and with the terminal pinion about the rotation axis;
• and
• the second mechanical connection comprises a series of first teeth arranged on the first distal end of the intermediate shaft and a series of second teeth arranged on the terminal pinion, around the first teeth with respect to the rotation axis, a drive ring comprising a series of connecting teeth separated by radial intertooth spaces, each first tooth and each second tooth being in contact with the connecting teeth in a radial intertooth space, and a fastening device connecting the drive ring axially along the rotation axis with the intermediate shaft and the terminal pinion.