| 摘要 |
PROBLEM TO BE SOLVED: To provide a structure capable of suppressing worm teeth from being displaced in a direction perpendicular to a direction of engagement between the worm teeth and a worm wheel and an axial direction of a worm shaft while suppressing a tooth hitting sound from being generated at an engagement part between the worm teeth and worm wheel even when the worm wheel rotates in either direction.SOLUTION: An energizing member 24 constituting energizing means 21 is arranged in such a state that a modulus of section associated with a direction of a bisector between a vector of engagement reaction force applied to a worm shaft 6a when a worm wheel is rotated in one direction and a vector of engagement reaction force when the worm wheel is rotated in the other direction is minimum and a modulus of section associated with a direction perpendicular to the direction of the bisector and the axial direction of the worm shaft 6a is maximum. Then the energizing member 24 is elastically deformed to press a tip-side bearing 9a toward the worm wheel 4 as to the direction of the bisector.SELECTED DRAWING: Figure 2 |
