One of the first technical papers to reference ‘Graunching’ was ‘Railway Noise: Curve Squeal, Roughness Growth, Friction and Wear’ (Report: RRUK/ A, 2003, D.J. Thompson, A.D. Monk-Steel, C.J.C. Jones. P.D Allen, S.S. Hsu, and S.D. Iwnicki)
“Other related forms of curving noise include ‘graunching’ at switches and crossings (possibly due to flange rubbing), [and] ‘juddering’ thought to be caused by unstable dynamic behaviour of the vehicle…”
The subject surfaced again in ‘Noise emissions of transit trains at curvature due to track lubrication’ (Indian Journal of Pure & Applied Physics, 2010, Vol 48 , Dec 2010, pp 881-885, Naveen Garg and Omkar Shama.)
“Other forms of noise associated with curving as reported in literature include a low frequency ‘graunching’ at crossings due to flange rubbing and ‘juddering’ due to unstable dynamic behaviour of the vehicle.”
This time, however the authors’ line of enquiry not only proposed a solution (greasing the rails) but they also steamed ahead with an experimental platform to gauge their hypothesis. Sadly however, the experimenters train of investigation appeared to be on the wrong track, at least with regard to squealing and flanging :
“The present work shows the non effectiveness of gauge face lubrication in combating the squealing and flanging noise.”
And graunching did not get a further mention in the paper – but we could assume that if it had been reduced, then the authors might have mentioned it.
So to run over the main points again, a solution to squealing and flanging is still overdue, and it seems there is no light at the end of the tunnel to signal a possible de-graunching solution.
Coming soon : Railway vibrations – part 2 – ‘Jiggling’.