In this paper, a novel point-contact hourglass worm drive based on modified involute is proposed, it is composed of a modified involute gear and an hourglass worm enveloped by a standard involute gear. The involute modification method and criterion of the standard involute gear are proposed, four representative modification functions are established, and the mathematical model of this novel transmission pair is derived. The tooth contact analysis (TCA) is simulated by numerical analysis and finite element analysis (FEA); the effect of the modification position and modification amount on the contact stress is studied by transient structural analysis; the error sensitivity to center distance error, shaft angle error, and comprehensive error was studied by FEA. All these results of the analysis demonstrated that the tangible contact areas are in line with the theoretical contact points, the average stress value and variance are less affected by the modification position, and the novel worm pair has good error adaptability. This study aims to provide a new idea for the configuration of an hourglass worm drive with local conjugate meshing.
