Mechanical device comprising an input pinion and an output pinion that are able to rotate about a rotation axis, an intermediate shaft extending longitudinally along said rotation axis from a first proximal end to a first distal end, a first mechanical rotational drive connection connecting said intermediate shaft and said input pinion, a second mechanical connection connecting the first distal end of said intermediate shaft and said output pinion, the mechanical device comprising a torquemeter cooperating with said intermediate shaft, wherein - said torquemeter is a torquemeter with a phonic wheel provided with a reference shaft extending longitudinally along said rotation axis from a second proximal end to a second distal end, said reference shaft being arranged at least partially inside said intermediate shaft and being coaxial to said intermediate shaft, said second distal end of said reference shaft being connected to said intermediate shaft, said torquemeter comprising at least one measuring index secured to said intermediate shaft and arranged at said first proximal end and at least one reference index secured to said reference shaft and arranged at said second proximal end; - said intermediate shaft is coaxial with said input pinion and with said output pinion about said rotation axis; and - the second mechanical connection comprises a series of first teeth arranged on said first distal end of said intermediate shaft and a series of second teeth arranged on said output pinion, around said first teeth with respect to the rotation axis, and characterised in that it comprises 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 said connecting teeth in a radial intertooth space, and a fastening device connecting said drive ring axially along the rotation axis with said intermediate shaft and said output pinion. wherein - said torquemeter is a torquemeter with a phonic wheel provided with a reference shaft extending longitudinally along said rotation axis from a second proximal end to a second distal end, said reference shaft being arranged at least partially inside said intermediate shaft and being coaxial to said intermediate shaft, said second distal end of said reference shaft being connected to said intermediate shaft, said torquemeter comprising at least one measuring index secured to said intermediate shaft and arranged at said first proximal end and at least one reference index secured to said reference shaft and arranged at said second proximal end; - said intermediate shaft is coaxial with said input pinion and with said output pinion about said rotation axis; and - the second mechanical connection comprises a series of first teeth arranged on said first distal end of said intermediate shaft and a series of second teeth arranged on said output pinion, around said first teeth with respect to the rotation axis, - said torquemeter is a torquemeter with a phonic wheel provided with a reference shaft extending longitudinally along said rotation axis from a second proximal end to a second distal end, said reference shaft being arranged at least partially inside said intermediate shaft and being coaxial to said intermediate shaft, said second distal end of said reference shaft being connected to said intermediate shaft, said torquemeter comprising at least one measuring index secured to said intermediate shaft and arranged at said first proximal end and at least one reference index secured to said reference shaft and arranged at said second proximal end; - said intermediate shaft is coaxial with said input pinion and with said output pinion about said rotation axis; and - the second mechanical connection comprises a series of first teeth arranged on said first distal end of said intermediate shaft and a series of second teeth arranged on said output pinion, around said first teeth with respect to the rotation axis, and characterised in that it comprises 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 said connecting teeth in a radial intertooth space, and a fastening device connecting said drive ring axially along the rotation axis with said intermediate shaft and said output pinion.