A Measuring Method of Gear Accuracy by Means of Two Feelers

Abstract

Up to this time, the accuracy of gears has been expressed in terms of individual errors such as the pitch error, the tooth profile error, the eccentricity ett., or in terms of the total error from the single or double surfaces meshing test. Each of these methods, however, is not satisfactory ot express the accuracy of gears. The authors present a new method to measure the error of a gear. Two feelers contact simultaneously on two adjacent surfaces and draw error curves in the same way as in the case of a usual profile tester. The center distance of the two feelers is set equal to the normal pitch of the gear. Consequently, two curves of profile errors are recorded on the paper. The entire error curve around the gear teeth is obtained by superposing these individual curves. By this new method, the accuracy of gear is more adequately expressed than by any of the conventional methods. This method is convenient in other respects, for example, the analysis of the cause of error becomes easier, the testing procedure less laborious and the whole apparatus less expensive.