BACKLASH PREVENTIVE MECHANISM OF WORM SHAFT AND WORM WHEEL

摘要

PURPOSE:To prevent backlash of a worm gear which is employed in a steering device of an automobile. CONSTITUTION:In a steering device which turns a worm shaft 8 in accordance with running conditions of a car body and changes the position of an input shaft by a worm wheel portion 5a which meshes with the worm shaft 8, the thickness of teeth of the worm shaft 8 is gradually changed from a thin wall to a thick wall, and the worm shaft 8 is caused to mesh with the worm wheel portion 5a so that an interval between tooth grooves in the worm wheel portion 5a coincides with the thickness of teeth of the worm shaft 8 at a central part (on O-P line) where the worm shaft 8 meshes with the worm wheel portion 5a so as to prevent backlash.