A review of the history of the analysis of torsionally induced shaft stresses due to the inclusion of an empty keyway, or keyseat, is given with emphasis placed upon experimentally measured values. More realistic stresses recently found by photoelastic analysis of a shaft in which the keyways were not empty are then presented. A new, patented (U.S. Patent 3 920 343, Nov. 18, 1975 assigned to the U.S.), and operating key and keyway design which resulted from these tests, wherein the twisting forces were actually applied through the keys, is described toward the close of the paper.

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Finding the number of teeth for each gear in a gear train required to provide a specified noninteger ratio (or its inverse) of angular velocity between input and output shafts has been a troublesome problem throughout the history of gearing. A direct method for finding the required number of teeth is presented, along with a program for its implementation on a programmable pocket calculator.

A theoretical foundation is provided for the difficulties encountered in manufacturing a snap acting bimetallic strip thermostatic which will snap within ±10 degrees of a prescribed temperature. It is obtained by modifying Timoshenko’s pioneering analysis to allow for a realistic support frame whose coefficient of thermal expansion differs from the composite coefficient for the bimetallic strip. Results are compared with those of Timoshenko and with predicted behavior when the support frame is rigid and thermally inert.