Torque and force sensors as solutions in railway applications
The train is considered to be one of the safest and most comfortable travel options of our time. Over the past decades, it has undergone significant development in terms of safety and efficiency. Sensors for safety and functionality are an everyday item on the agenda of railway engineers and their suppliers. But a lot has also happened in the field of electrification in recent years and force and torque sensors make this development more efficient.
At which point in railway applications is it possible to measure forces and torque?
- Brake systems
- Wagon axles
- Current collectors
- Car Coupling
- Infrastructure
Sensors in multi-stage braking systems
Sensors in the brake systems can measure the load on the axle and regulate the braking force accordingly. The braking systems of the railway are divided into several stages. From light braking to the actual stop, there are various systems that mutually cooperate. A few decades ago, passengers would have to hang on in order to keep their feet on the ground. Torque sensors installed in the brakes or wheel axles can measure the forces acting on the mechanics during the braking process and regulate the braking force on the basis of these forces. In this way, closed-loop brake controls can be implemented.
How the force sensor contributes to safety: load management
In addition to brake force control, sensors are also used in the area of load management. For example, the force sensors in the boarding area can count how many people have boarded or disembarked the train. Force sensors can also determine how heavy the load is on the wagon axle and how it changes in the course of the load. This is particularly interesting in freight transport, where the cost of transport is calculated from the weight of the load and volume. In this way the railway operator can check the data of his customers. Similar circumstances can be found with the e-mobility truck of the future, as the load has a significant influence on safety and costs there as well.
Early detection of malfunctions
Force sensors are also used in the field of pantograph shaft transducers. The contact force of the pantograph to the overhead contact line defines the quality of the electrical connection. If this is too weak, it is possible that the electrical contact resistances are too high and, as a result, a drop in performance takes place accordingly. If the load is too high, malfunctions may occur. According to the „Pro-Rail Alliance“, 60 percent of the rail network is already electrified. By 2025, 70 percent of the tracks are to be equipped with conductor rails or overhead lines. In addition, the electrified tracks will pave the way for electric rail drives, as charging, for example, can take place directly via the overhead lines. In trains, large forces and loads also occur in the area of the wagon couplings. Force transducers at these positions can determine the train loads and issue a warning in the event of overload or, for example, unintentional disconnection.
Where else are force sensors used?
The application possibilities for torque and force sensors in the railway sector are very diverse. The integration of sensors into the railway infrastructure is also an exciting topic. For example, there are systems that monitor how many trains have crossed the rails or how many axles have passed a point. This information can be used, for example, to implement emergency shutdowns on track sections, e.g. if a wagon is still standing there and another train is already arriving. Some of these sensors are based on optical as well as ultrasonic technologies. By integrating force sensors on the rails, the signal quality and the robustness of this measuring method can be refined. Due to the technology of magnetic inductive force sensors, which can be easily integrated at any measuring point, it is possible to retrofit these measuring methods to already existing track sections.
