Wireless Sensors

In order to meet the high operating safety demands of the railways, a sensor system was developed that continuously monitors the temperature of the wheel bearings on passenger trains. In addition to the extreme operating environment influenced by vibrations and mechanical stress, special requirements result from this country's different climate zones, in which the system must operate. The system must work reliably in temperatures from -40 °F to +185 °F. In order to reduce maintenance requirements and avoid problems with cable connections, which experience has shown to be susceptible to failures, a special wireless concept was developed for transmitting the measurement values.

The sensors, which are encased in synthetic resin, are fitted to the wheel bearing case and then activated for operation. The license-free 2.4 GHz ISM band is used to transmit radio signals from the sensors. Each car has eight sensors, which transfer information to the receiver underneath the car on a cyclical basis. Batteries with a lifecycle of approx. 6 years are used to power the sensors.

The receiver is connected to the display module in the car via a data cable and forwards the measurement values for continuous display on a continuous basis. The train personnel can then check the current values at any time. If specified temperature values are exceeded, warning or alarm messages are forwarded to the train's internal communication system via appropriate interfaces. These messages are then passed on to the maintenance personnel on the train or in the operating control centre, where appropriate measures can be initiated.

If required, additional sensors can be added to the system in order to measure different values e.g. GPS data, acceleration speeds, fill levels or meter readings. The solution can be easily adapted to meet individual customer requirements and thus represents an alternative system for other railway companies.