Abstract
A new fatigue testing machine for high speed roller chain is designed. The principle of testing method of this machine is to give repeated impact to a test piece by a sprocket tooth. A test piece is composed of several pitches of roller chains and it is stretched by two helical springs with any inital tension. A block which has only one tooth form of sprockes it reciprocated by a crank mechanism, and gives impact to the test piece. The dynamical relation is analogous to the chain gearing at high driving speed. Usually rollers come into failure by repeated impact. Taking the driving speed as ordinate and number of impact repetitions as abscissa, we obtain S-N curves as in usual fatigue tests. As an example, we showed some experimental results. If the testing machine is driven at low speed with a long reciprocating stroke, the test piece receives small impact and high repeated tensile stress. Then link plates of roller chains fail. Many experimental results carried out by the new testing mahine will be shown in later reports.
