Using a simple model, various modes of instability have been identified for four-axle vehicles with bogies having steered wheelsets, and simple stability criteria have been derived. The analysis shows that the origin of these modes of instability varies; some instabilities, occuring at relatively high speeds, are the result of the combined action of creep, conicity and inertia similar to bogie hunting of conventional vehicles. At low speeds, both static instabilities or divergences and oscillatory instabilities can occur. Low-speed divergence has been shown to be the result of fore-and-aft asymmetry and is not peculiar to vehicles with steered wheelsets. The origin of the low-speed oscillatory instabilities lies in the arrangements for the steering of the wheelsets. Yet more modes of instability involve interaction between the steering modes and the modes of the vehicle body oscillating the secondary suspension. These body instabilities can as a general rule be avoided by a choice of secondary suspension parameters. The simple analyses given here are not intended to be applied in assessing the performance of actual designs, which should be subject of realistic simulation, but are intended as an aid to the understanding of system behaviour. Nevertheless, comparison of the results of these analyses with more extensive vehicle models shows a surprising degree of agreement over a wide range of parameter values and therefore the trends illustrated here are at least qualitatively correct. The results suggest that provided low conicities, low creep coefficients and extreme values of elastic stiffness are avoided, an acceptable margin of stability can be achieved over a wide range of speeds for configurations that can steer perfectly on uniform curves.
Static and dynamic instabilities of bogie railway vehicles with linkage steered wheelsets
Statische und dynamische Instabilitäten bei Eisenbahnfahrzeugen mit verbundgesteuerten Radsätzen
Vehicle System Dynamics ; 26 , 1 ; 1-16
1996
16 Seiten, 8 Bilder, 8 Quellen
Aufsatz (Zeitschrift)
Englisch
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