Analog inductive sensors permanently measure primary spring position on tramcar suspension

Summary

A German technology leader in rail transport uses sensors to ensure safety and efficiency and to optimize the environmental performance of trams. Inductive sensors from the Extra Distance family, Analog Output range (series 509) provide continuous data on all vibration and movement of the primary suspension spring.

Application

In collaboration with engineers from the Technical University of Dresden and the city’s Public Transport Authority, the customer is designing and engineering urban transport solutions for sustainable mobility. To provide a smoother, more comfortable ride with a quieter, more reliable and energy efficient fleet, engineers are optimizing the performance of tramcar suspensions. Crucial to this effort is the sensor that measures movement of the primary spring in the suspension.

A digital sensor is unsuitable because it only supplies a switching point. Instead, an analog output is required to capture all spring motion, including every vibration. The rough environment of the suspension demands an extremely robust, contactless sensor with a long operating distance and resistance to dirt and wear.

Solution

An inductive sensor from the Extra Distance family, Analog Output range (series 509) is ideally suited to this application. It has excellent resolution (in µm range) and is particularly suitable for monitoring vibration, detecting motion and controlling travel smoothly.

Patented Condist oscillator technology gives these sensors enhanced environmental stability, particularly regarding temperature. Improved stability allows a longer operating distance of up to 40 mm (almost 3 times that of a conventional sensor) on the moving spring target.

Analog sensors output spring motion, including vibrations, as a continuous analog signal. This signal changes with the distance between the spring and the sensing surface. Data collected is stored on an external hard disk to be read by the service engineer. With the help of precise GPS position data, it is possible to define for each point in a journey the corresponding spring movement and mechanical loads.