| 摘要 |
PURPOSE:To automatically eliminate backlash, by fitting the internal face of a piece to the bottom surface of a notched part in a housing, forming an internal tread part, screwed to an external thread, in the internal face of the piece and press contacting said piece to an external tread shaft. CONSTITUTION:A piece 13 is pressed to an external thread 11 by spring 12. Under this condition, a thread of the external thread shaft 11 and internal threads 10a, 10a, are pressed to one direction, then looseness of a screw can be eliminated, accordingly its backlash can be prevented. Even though the screw is used for a long time and worn, a prescribed gap 14 is provided between a bottom face 10e of a housing 10 and the piece 13, then the gap 14 is only narrowed by a wearing amount of the screw, thus the external thread shaft 11 and the internal threads 10a are always in a pressed state to eliminate looseness of the screw. |
