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The New Zealand Railways Magazine, Volume 3, Issue 5 (September 1, 1928)
Theory of Bunching
Theory of Bunching.
It is not always clear what witnesses have in their minds when putting forward this theory. It is a purely speculative theory, unsupported by evidence, to explain a derailment. In fact these theorists say that trucks run up together, mass, and then either break their couplings and pile on each
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other, or are pitched out of the centre line of gravity. Trucks of many tons capacity are supposed to act contrary to laws of gravity! Speed, change of grade, and application of the brake are all given as combining to produce this “bunching” effect.
Newmarket Railway Fire Brigade, 1928.
Back Row (left to right): Messrs. R. L. Corles, M. F. B. Judd, J. Billingsley, L. S. Johnson, C. Thomas, J. R. Ellwood, and A. T. McDonald.
Front Row: Messrs. W. Johnson, P. A. E. Beauchamp, A. G. Williams (Captain), and J. Elliott.
If we take Beaton on “Speed of Trains” and Shannon on “Derailments and their Causes,” we find that speed is not such an important factor in derailments as is generally supposed. Assuming that the track is in good order and that the permissible speed is not exceeded speed can safely be eliminated as a factor in most derailments.