Progress in Design and Application of the Lysholm-Smith Torque Converter, with Special Reference to the Development in England

Abstract

The Lysholm-Smith torque converter is of the closed-circuit turbine type. An approximate balance sheet is given showing the principal losses. As a torque converter is required to run at widely different primary and secondary speeds and torques the blade losses at varying inlet angles are the most important, particularly at starting and at secondary speeds, where the output torque is equal to or less than the input torque. A brief theory of the effect of blade friction is given together with the results of some experimental work with a reaction balance. The first converter was based on these results, and after it had been tested in England and Sweden, several experimental units of 100 to 150 h.p. were made. From the experience gained with these the present design was evolved. The main points to be provided for in the design and manufacture of the torque converter are set out and the experimental and production testing is described. Difficulty was found in presenting the test results in a simple form which would give the complete characteristics of the converter with all possible combinations of primary and secondary torques and speeds, but a method was devised such that if the torque-speed curve of the driving unit is given, a curve can be immediately constructed to give the combined action of the driving unit and the converter for the complete speed range. The results of experiments showing the alterations produced by various blade angles and wheel diameters are given, and various applications of this type of transmission are described, including a 1,000 h.p. variable-blade converter.