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Inductive wheel sensors are reliable, robust and flexible. These characteristics make them the ideal basis for existing and new applications in the railway industry. Martin Rosenberger, Chief Technology Officer (CTO) at Frauscher, presents a few examples.

Inductive wheel sensors are now being used in many railway markets around the world as a basis for axle counters. Their key function is track vacancy detection. In this function, they are also often used as signal generators for level crossings.

The establishment of the technology in different regions and railway segments around the globe does however mean that new areas of use are constantly being discovered for wheel sensors. Their possibilities are wide-ranging. In different installations, they can therefore reliably provide information about the presence of a train, its speed or direction of travel. Wheel centre pulses or wheel diameters can also be evaluated.

Flexibility of course plays a significant role here. And in order to meet the project- or market-specific requirements, models already established elsewhere have to be adapted in some circumstances. This always occurs as a balance between the conflicting priorities of demand, technical characteristics and know-how.

It was from here that the key points for the development of the Frauscher Wheel Sensor RSR110 were derived, which, due to its open, analogue interface, can be easily and quickly integrated into any infrastructure. Nowadays, this sensor is available in two system variants: the RSR110 contains two sensor systems, the RSR110s has one sensor system. Very individual systems can therefore be set up with the RSR110 which are supplied by the wheel sensor with precise measurement data.

Strong partner for innovative systems

Increasing electrification of railway lines means that installations for different tasks in the railway industry have to satisfy ever-increasing challenges in fields such as EMC. Manufacturers of such systems often rely on inductive wheel sensors these days which, also demonstrate a level of robustness with respect to electromagnetic compatibility.

Hump yards: new components for tried-and-tested concepts

Hump yards are still an essential part of many shunting systems. Wheel sensors can undertake various tasks against this backdrop, such as speed measurement.

Points which are used to assign the wagons to the relevant trains, can be reliably set with the help of inductive wheel sensors. Furthermore, they facilitate – like when wagons may have to be weighed – accurate positioning via wheel centre pulse.

An installation of this type has been in use in North America since September 2017. Ongoing problems with the existing infrastructure have meant that the operator has had to look for alternatives. The decision was made to install two RSR110 at the top of the hump yard.

The pulse for setting two points is sent by additional RSR110s’ to the relevant point mechanism. The trains are identified and sorted via an Automatic Equipment Identification (AEI) system. It was possible to incorporate the wheel sensors into the AEI system and the control centre of the system integrator without any further adaptations. Since being commissioned, the system has worked to the customer's complete satisfaction.

Detecting, counting, measuring and activating

Wayside Inspection Devices Inc. from Canada can be found far beyond its domestic frontiers. The company’s laser based TBOGI system measures the bogie geometry of passing trains. It identifies, at a very early stage, bogie misalignments leading to accelerated wheel wear and subsequent rail wear, allowing corrective action to be taken before severe wear sets in. Such deviations could otherwise lead to the rapid wear of train wheels and could subsequently even damage the tracks.

The wheel sensor RSR110 is used here to indicate the presence of a train and its direction of travel, its speed and to measure the distance between individual axles and to activate and then deactivate the recording of data by the TBOGI system.

“The sensor was implemented using a specially developed hardware interface which digitises the signal. Costly adaptations to the hardware and firmware of the TBOGI system were not necessary. The company’s laser based TBOGI system measures the bogie geometry of passing trains. The high precision of the RSR110’s measurement data is of significant relevance for our system,” says Denis D’Aoust. The president of Wayside Inspection Devices Inc. is convinced by the characteristics of the wheel sensor.

Frauscher wheel sensors offer various advantages, such as:

Track more with less

  • High resistance against electromagnetic interference
  • Reliable function under extreme conditions
  • Easy to install using the patented rail claw
  • Flexible interfaces for individual applications

Project EntKuRo

The role which the high precision of Wheel Sensors in particular can play is demonstrated by the EntKuRo project – a “decoupling robot”. This is being promoted by the Austrian Federal Ministry for Transport, Innovation and Technology (BMVIT) and the Austrian Research Promotion Agency (FFG) as part of the “Mobility of the future – freight mobility” programme. The project partners are the University of Applied Sciences Upper Austria, ÖBB Infrastructure, the St. Pölten University of Applied Sciences, the Austrian Institute of Technology, and Ulbrich.

“European rail freight transport is still characterised by the screw coupling which was developed in the 19th century. It is designed for manual operation and does not meet the requirements of today in terms of productivity and occupational safety,” reports Christoph Zellner from the University of Applied Sciences Upper Austria on the background of the project. Zellner explains: “With the EntKuRo project, the processes for separating wagons was analysed and after that a mechatronic device was developed which separated wagons completely automatically.

On a test track at the shunting yard in Linz, the decoupling robot is tested under real conditions. In order to successfully develop a system like this, a variety of sensors is needed, such as the Frauscher Wheel Sensor RSR110. This makes it possible to not only reliably determine the number of axles and to compare this to the database, but also to give the approval for the decoupling process. The evaluation of the signal edges also makes it possible to calculate the speed of the passing train. The wheel sensor is hereby an essential factor in the safe and reliable decoupling process.”

Precise train detection remains on the agenda

Even this small selection of application examples for a single sensor model shows how important this technology will be in the future railway industry.

Especially with regard to accuracy and reliability, inductive wheel sensors will continue to be state of the art for a long time to come. Additional characteristics such as the establishment of various models with separate wiring options or open interfaces, make these devices even more competitive.


The RSR110 has already been used in various projects because of its open analogue interface and its positive characteristics. The current signal can be evaluated completely as desired using simple electronics, a PLC or a microcontroller. This reduces the number of hardware components as well as the space requirements and power consumption. The threshold values for triggers and the sample rate can be freely selected depending on the application at hand. For systems where tailored software integration is not required, the wheel sensor information can be digitalised using the Frauscher Wheel Sensor Signal Converter WSC.

On a number of occasions, the RSR110 has also successfully replaced individual sensors. To further simplify this process, Frauscher developed a sensor model which has only one sensor system and enables the corresponding wiring to be implemented. A distinction is now made in the portfolio between the RSR110 double with two sensor systems and the RSR110 single with one sensor system. Following years of experience developing reliable sensors, Frauscher has created an extremely flexible product which allows a whole range of applications to be implemented. This meant that well-known applications could be significantly improved and completely new approaches could be developed.

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