Track box - VTI SL

The dynamic load application system on track rails for train passage simulation consists of:

- 4 couples of dynamic servo-hydraulic actuators with a maximum load and frequency of 250 KN at 50 Hz that simulate the precise passage of each wheel of the train and

- 2 piezoelectric actuators with maximum load and frequency of 20 KN at 300 Hz for the reproduction of the dynamic effects that are induced by imperfections in the rail.

The project has involved the development of a precise real-time control that allows:
 
- Individual actuator high-precision closed-loop control by means of a 3-stage servo-valve or a load amplifier depending on the actuator nature (hydraulic or piezoelectric).
 
- Integral Control: synchronization of each of the individual load profiles to compose the required global load application

The system installed in the track box of the Geotechnical Laboratory of the CEDEX in Madrid allows to perform on 1: 1 scale fatigue tests on the components of the superstructure of the rail (rail-cross ties, ballast), and its infrastructure (sub-ballast, shape layer, embankment) in which the passage of millions of axes is simulated. 

This allows reproducing the effect of the train passage in real section for a year in a single week.