Magnetic speed sensor

A speed sensor for a vehicle wheel comprising a tone wheel driven by the vehicle and subject to axial misalignment and vibration, the tone wheel being made of magnetic material and having a plurality of teeth, and sensing means having a pair of poles of magnetic material proximate the tone wheel teeth, coil means on the poles, and a permanent magnet having one of its poles connected to the poles on the sensing means for magnetizing the poles on the sensing means to induce a signal voltage in the coil means corresponding to wheel speed upon rotation of the tone wheel relative to the sensing means, the poles on the sensing means being phased relative to the teeth on the tone wheel to reduce noise voltage components in the wheel speed signal voltage due to axial misalignment and vibration of the tone wheel, and a substantially U-shaped shield connected to the other pole of the permanent magnet and enclosing a substantial portion of the sensing means from electromagnetic noise, a portion of the U-shaped shield being positioned adjacent the tone wheel remote from the teeth to provide a return path for magnetic flux.