DMA Train Hunting Measurement (THM)

Train Hunting Measurement is crucial to detect dangerous wheelsets by the amplitude of their hunting motion.

The DMA Train Hunting Measurement (THM) system consists of several measuring units at appropriate distances to perform contactless measurements of the wheelset position.

THM system is an effective technology solution to detect dangerous wheelsets (excessive hunting, non-centered running wheelset, etc.) and can provide wheel radius differences.


  • Each unit detects and measures the passing wheelsets’ transversal position and angles
  • The units do not affect the line traffic
  • Each module is composed of two measurement heads for each wheel, one per side
  • Wheelset lateral displacement measurement
  • Back-to-Back gauge measurement
  • Wheelset hunting motion amplitude measurement
  • Wheelset hunting motion wavelength measurement
  • Radius difference estimation