A Study of Pin-Wheel Globoidal Worm Gearing

Abstract

A globoidal worm gear of a new type which consists of a wheel having cylindrical pins as teeth and a worm with an arc-shaped groove is proposed. The gear has merits of easy manufacturing and maintenance. The geometrical characteristics are examined in the first section of this study. A slightly skewed shaft angle is proposed to realize good performance of lubrication and a design example is shown. The second section deals with an experiment of lubrication between a cylindrical pin and a rotating roller with an arc-shaped groove to obtain the optimum groove profile of the worm. A method of machining the worm gear unit is presented in the third section and two pairs of the units with a gear ratio of 1/24 are manufactured for trial using a hobbing machine. The last section deals with a performance test of the worm gear units. A transmission efficiency of 80% max. is obtained showing satisfactory abilities of the units for practical use.