Long Trains test bench Following the American growing ... - UIC

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SNCF kindly supplied measurements about such a long train, but the composition was mixed Ø 1” and Ø 1”_, in a unknown wagon configuration, so it was impossible to accurately reproduce the real case. The Data Acquisition System The LTTB has been equipped with a Data Acquisition System DAS able to monitor and collect pressure data during the simulations, developed and realised by SAB-Wabco. The hardware characteristics of the DAS are: 200 pressure transducers installed on 50 wagons out of 132; the wagons are monitored in four different points: the brake pipe, the auxiliary reservoir, the control reservoir , the brake cylinder. the pressure transducer precision is within ±1%the full range. An embedded calibration process increases this precision the sampling rate of the DAS is programmable up to 200Hz (5ms. acquisition period) all the 200 transducers are acquired in less than 1ms. in order to have a negligible “time skew” with respect the maximum sampling rate The software characteristics of the DAS are: recording and saving capabilities replay, rewind and fast-forward functions cursor are available during the replay function, for detailed measurements Two kind of visualisations are available on the screen: visualisation versus time visualisation versus train length. While the visualisation versus time is useful to verify the time dependence between different inputs, the visualisation versus train length becomes relevant to observe and compare the different pneumatic behaviour of the long train when in UIC mode and when in FEBIS mode. The next picture shows an example of visualisation versus time, where two pressure transducers waveforms are shown: in particular, the two pressure transducers are located on the Brake Pipe, 2153m. distant one each other, and the acquisition is performed during the propagation of the accelerating chambers wave. The period between the two falling edges is 7.52s and evidences a wave propagation speed of 286m/s.
Accelerating chambers wave propagation The next picture shows an example of visualisation versus train length, where the four Pneumatic Brake subsystem magnitudes are shown: brake pipe (blue) auxiliary reservoir (red) control chamber (yellow) cylinder (green) The picture has been captured during a brake application in conventional UIC mode, 25s after the brake application start (distributors in P mode).
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Page 9 and 10: LCU’s installed on the LTTB The t

Long Trains test bench Following the American growing ... - UIC

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