Speed probes

Speed probeA speed probe is an alternating voltage generator producing an electrical signal. The frequency of this electrical signal is proportional to the engine shaft speed. A speed probe contains one or two coils and a rare earth permanent magnet.

In rotating machinery the speed probe sensing surface faces the phonic wheel. As the magnetic flux varies in density with the passage of each tooth, these changes induce an alternating voltage in the coil surrounding the permanent magnet, the frequency of which is a function of shaft speed.

Features of Meggitt speed probes

  • One or several complete enclosed sensing elements
  • Active system, no supply voltage required
  • Wide temperature range
  • Advanced wire interconnection technique
  • Hermetically sealed construction
  • Stainless steel, titanium, or Inconel 600 housing
  • Designed for aircraft engines
  • No scheduled maintenance
  • High MTBF - basic design adaptable for customized construction

Speed probes applications

  • Shaft rotational position
  • Direction of rotation
  • Shaft torque
  • Rotor revolution
  • Wheel speed