| 摘要 |
PURPOSE: An operation auxiliary device is provided to prevent teeth which are deviated from each other when a rack and a gear are meshed with each other, from interfering with each other, and to ensure, more or less, a strength of meshing between the rack and the gear in a normal condition, and to facilitate processing and assembling of components. CONSTITUTION: In a structure for meshing a gear(36) rotated by a drive force from a drive source, with a rack(51) which is disengageably engaged with the gear(36, and which is rectilinearly moved in a predetermined direction through rotation during engagement of the gear(36), when the gear(36) is meshed at first with the rack(51) through teeth(36a1),(51a1), the first tooth(36a1) can pass by a position where it is axially overlapped with teeth(51a) of the rack(51) subsequent to a second tooth, and after passing by the position, it is meshed with the first tooth(51a1) of the rack(51) so as to initiate the meshing between the gear(36) and the rack(51).
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