The performance of longitudinally vibrating earth cutters

Abstract Performance curves are presented for longitudinally oscillating earth cutters of the kinematic type in which the speed of the cutter consists of a sinusoidal component superimposed on a steady speed of advance. It is shown that performance can be defined in terms of mean draught force reduction, and mean power increase as functions of the ratio of vibratory velocity to the mean speed of advance. The friction between cutter and soil when it is moving backwards and forwards but not penetrating undisturbed soil is shown to cause substantial power increases. If the friction when the cutter is backing off is less than that when it is catching up then the reduction in mean draught force is greatly decreased. Similar performance curves are provided for dynamic vibrators in which the vibrations are caused by oscillatory forces rather than a sinusoidal linkage. In this case it is necessary to introduce an extra parameter, the harmonic force ratio. A selectiion of experimental results are provided to show that in practical situations the performance may range between the best and worst of the theoretical predictions.