Device for a torque or shear transmitter for determining fibre concentration or viscosity in pulp suspensions and which is adapted to measure an angle deviation between two concentric shafts whereby the angle deviation forms a function of the torque applied on the measuring body. The device includes a feedback system for bringing the inner or measuring shaft to a zero position independent of the magnitude of the torque. The system includes an electromagnetic feedback coil, which encircles two pole shoes journalled in bearing points at the end of the outer shaft, at the same time as each pole shoe is connected to the measuring shaft, whereby a current, generated by a transducer and dependent on the angle deviation, is sent to the winding of the coil, where a magnetic field of force is generated.