Abstract: A dynamometric measuring device for a drill pipe which includes, firmly attached to the rotating pipe, sensors disposed in a groove on the pipe and electronics for conditioning the signals supplied by the sensors. The measurement signals are transmitted by a commutator-fixed brush assembly to a fixed, non-rotating part. By providing follower-amplifiers of very low output impedance on the commutator, rotating, portion of the assembly and follower-amplifiers of very high input impedance on the fixed brush side of the assembly, the transmission of signals is carried out at zero current. To assure high quality signal analysis, a separation circuit on the fixed brush side of the assembly separates the DC and AC components of the signal prior to transmission to the surface.