Target wheel sensor

A target wheel sensor includes a sensing structure (112) disposed within a hollow sensor housing (102). The sensing structure (112) has a T-shaped spool (114) that includes a pole piece holder (116) that terminates in a magnet holder (118). Moreover, a pole piece (120) and a magnet (122) are slidably engaged within the pole piece holder (16) and the magnet holder (118) respectively. The magnet (122) and the pole piece (120) are magnetically coupled so that the pole piece (120) is magnetized by the magnet. Also, the magnet (122) and the pole piece (120) are physically coupled so that they move in unison within the sensing structure (112). A metal target wheel (130) having one or more teeth (132) is provided and works in conjunction with the sensor (100). The target wheel (130) is placed in proximity to the sensor (100) and as the target wheel (130) rotates and a tooth (132) passes by the sensor (100) the force of magnetic attraction between the pole piece (120) and the tooth (132) will draw the pole piece (120) toward the target wheel (130) and into the extended position. As the target wheel (130) continues to rotate, the tooth (132) will move away from the pole piece (120) causing the magnetic force to lessen and allowing the pole piece (120) to return to the retracted position under the influence of a spring (128).