Abstract
Abstract
There is a lower limit to the maximum stress in a bar that is moved longitudinally at constant velocity and reversed at one end in a finite time, the other end being free. The lowest possible value of the maximum bar stress during a single reversal is determined for the general case and equations to define cams that achieve it are established. These cams have the disadvantage of giving much higher stresses when run above or below the speed for which they were designed.
Another type of cam without this disadvantage is obtained by reversing through two parabolic arcs which are selected to minimize the maximum bar stress. Proof that the selection is the best obtainable from two parabolas is derived from solutions in terms of progressive stress waves with consideration for light damping. Specification of this type of cam and measurements of the stresses in ‘traverse bars’ reciprocated by such cams on machines for winding yarn are included.
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