A wheel speed sensor including an annular rotor rotatable with a wheel, or the like, has circumferentially distributed surface interruptions. A sensing device fixed against rotation faces the rotor and includes a source of magnetic flux and a coil to generate an electrical signal variable with changes in the magnetic flux through the coil. The sensing device further includes first and second pole members extending from opposite poles of the flux source and spaced so that one pole member opposes a surface interruption on the rotor while the other faces the rotor surface between surface interruptions, and vice versa, to provide a magnetic flux path between the rotating rotor and alternating ones of said first and second pole members. A third pole member extends past the coil and has one end opposing the rotor and wider than the surface interruptions to maintain continuous flux transferring relation with the rotor. The third pole member at its other end is coupled to a coil core extending through the inside diameter of the coil. The coil core is connected to a shunt which in turn is positioned to establish two predetermined air gaps between the first and second pole members respectively. As the rotor rotates, the resulting flux in the coil core alternates in direction as the first and second pole members traverse the rotor spaces alternately.

A speed sensor assembly is mounted to a steering knuckle with a threaded fastener. The fastener is initially hand tightened until it is axially obstructed by a spacer provided on the speed sensor assembly. A tool then is used to apply high torque to the fastener so as to deflect or break away the spacer so that the speed sensor assembly may be tightly clamped to the steering knuckle by the fastener. The spacer prevents hand tightened speed sensor assemblies from being properly aligned with a tone wheel. Unless a tool is used to fully seat the speed sensor assembly, the assembly will give a false test signal indicative of improper or incomplete mounting.

Electromagnetic shielding apparatus is provided for a motor having a rotor and a stator wherein the shielding apparatus is characterized by the absence of an electromagnetic shield in the stator of the motor.

A bearing monitor for use with a canned motor pump having a wound stator and a rotor drivably coupled to an impeller, the rotor being mounted on radial journal bearings and axial thrust bearings within a containment can comprises a first and a second target embedded in an outer periphery of the rotor in axial proximity to a first and a second end of the rotor. The monitor includes a plurality of sensors mounted external to the containment can in axial proximity to each of the two targets and radially displaced approximately equally around the periphery of the containment can. A plurality of magnetic field generators create local magnetic fields coupled through the containment can, process fluid, rotor, and at least a portion of one target to one of the sensors. In response to each field, each sensor generates an output signal which varies as a result in a change in the magnetic circuit reluctance caused by bearing wear. A monitor circuit is coupled to the sensors and compares their output signals to generate a scaled output which is approximately linearly related to bearing wear. The output of sensors in the same axial plane are utilized to determine bearing wear in a radial direction, while the output of sensors in different axial planes are utilized to determine bearing wear in an axial direction. Electromagnetic shielding may be used depending on the environmental and operating conditions.