Pole Wheel

Pole wheel sensing is typically via radially mounted sensors (occasionally via axial mounting). All mounting and operational tolerances should be taken into account when determining the sensor/pole wheel air gap. ln the case of axial mounting axial shaft play should be taken into consideration. To maintain a relatively constant mark the space ratio of the sensor output signal during rotation of the pole wheel, the pole wheel/sensor air gap should be kept as small as possible.

Sensors that operate on the principle of changes to the magnetic flux require a ferromagnetic material pole wheel (iron, steel, castings). Stainless steel and plating with 8 % CrNi would not be suitable. For certain applications (turbochargers or for sensing with a large air gap), pole wheels with permanent magnets can be used. HF sensors require a pole wheel with metallic materials.

For optimum signal generation, pole wheels with an involute gear form, or alternatively, slotted or holed disks should be used. Stamped sections (pole bands), bolts and screw heads can also be used. It must be ensured that the air gap between the part and the sensor remains the same. 

Please refer to the datasheet for optimal sensing recommendations for runout, float, and holes/slot gaps and limits.