Abstract: A sensor for measuring the relative displacement between two rotating shafts. The sensor can sense a torque applied to the steering wheel of a vehicle. The sensor has a housing that has apertures at each end. The rotating shafts pass into the housing. A sensor assembly is located in the housing and connected to the shafts. The sensor assembly generates an electrical signal that is proportional to the relative rotational displacement between the shafts. An electrical connector is located in the housing and electrically connects with the sensor assembly. The sensor assembly has a planetary gear assembly that is connected to the shafts. A variable magnetic field generator is connected to the planetary gear assembly and moves proportional to the relative rotational displacement of the shafts. A magnetic field sensor is located adjacent the variable magnetic field generator and generates the electrical signal as the variable magnetic field generator moves.