A tentative effort to model hunting behaviors of some old locomotives by means of simple non linear circuit equations

A very rough model is proposed for some types of railway locomotives, looking for investigating the unsatisfactory behavior of old prototypes, due to heavy hunting oscillations which prevented height speed service in the third decade of the last century. The model was first suggested by the similarity of the usual piecewise taper profiles and the Chua´s diode characteristic. This was interesting in order to enable chaotic behavior, and, although the final result is no longer a Chua´s oscillator, hunting behaviors have been observed in some agreement with those reported in the literature for a real locomotive class. In spite of its simple and largely arbitrary structure, the model seems to be effective in obtaining some results, but it required arbitrary tuning of parameters.