Steel and tire wheel presence sensor (DRF, DRF MP)


The DRF (or steel Wheel Safety Sensor) allows you to detect bogie wheel passage safely by detecting the metal mass in the wheel flange. It can be affixed against a square running track without perforation. If the detector is distanced more than 7mm from the track (due to deficient clamping), it will be in a state that corresponds to wheel detection.

This device’s applications are:

  • Train axle counting for train detection (SIL4 level)
  • Train presence detection by track circuit replacement
  • Train passage detection used with grade crossing control
  • Detection of the passage of the train associated with hot box, tight brake or drawling part,
  • Crossing detection at a particular point (KPG function)
  • All generally-ensured train signaling mechanical pedal functions (destruction pedals, signal unblocking pedals, axle counter, etc.)

Documents and ISA* Certification

Steel wheel presence sensor: Description

Used with a standard automat or a SIL4 safety automat with interlocking functions, WSS sensors help detect and protect train movement for signaling. The DRF is also used with the COPPILOT system.

The steel wheel presence sensor is made of 2 sensor units for direction detection. It is connected to a relay module located in a hotbox. There are two types of relay modules, depending on the outflow level when detecting a wheel: one is normally supplied (established work contact) and descends when a wheel is detected, the other is normally low (established resting contact) and rises when it detects a wheel.

Installations of the steel wheel presence sensor (DRF)

  • Lyon, T3 Grand Stade
  • Bordeaux, Plusieurs lignes de l’extension de la phase 3
  • Cameroun, Douala
  • Lépin le Lac

Technical informations

  • Detects all types of train wheel passage according to UIC 510-2
  • Maximum speed detection 350 km/h
  • Sensor service temperatures: from–40 to +80°C, humidity up to 100 %
  • Device service temperatures WSS: from -30 to +70°C
  • Sensor has IP68 protection
  • Sensor is mounted against the inner track rim
  • Universal sensor support compatible with all track types UIC60, S45 (other profiles available)
  • No track perforation
  • Protection against traction return, over-tension, atmospheric discharges…
  • Outflow relays comply with standard EN 50205
  • Reliability is increased thanks to contactless detection. This type of pedal doesn’t wear out, contrary to Forfex-type mechanical pedals.


The DRF-MP fulfils the same tasks the steel wheel presence sensor does but for tyres, works the same way and doesn’t require to cut the rails. It detects steel wheel presence up to 70 mm.

Why buy the DRF CLEARSY ?

  • DRF is a safe and tested product.
  • This product has passed all tests: more than 850 DRF sensors sold in the United Kingdom, Austria, Russia, Chili, Croatia, Serbia, Slovakia, Hungary, South Africa and Indonesia; More than 800 DRF sensors were sold for their axle counting ability in the USA, Germany, Austria, Croatia, Hungary, Slovakia, Serbia, Kosovo, Bosnia and Turkey.
  • Easy to install and doesn’t wear out like mechanical pedals.
  • The DRF application functions cover numerous operations (wheel detection, SIL4 axle counting, grade crossing command…)
  • We are available to answer your questions and help you. We would be happy to provide you with an in-depth study based on your specifications.
  • Competitive pricing in relation to mechanical pedals and other existing pedals.
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