| 摘要 |
PURPOSE:To attain simply and surely the control of high accuracy by providing the 1st rack member driving a loading mechanism, the 2nd rack member supported freely slidably to the 1st rack member and a notch part in response to the root of gear at the emshing start position of the 2nd rack member so as to prevent the 1st and 2nd transmission gear system from being locked. CONSTITUTION:The notch part 397 preventing locking due to meshing is formed to the vicinity of the root of gear of the 1st tooth part 393 from the root to a prescribed position. Further, the over-cut tooth part 398 preventing locking due to meshing is formed, where the tooth tip of, e.g., two teeth from the root is cut in an acute angle as shown in hatched lines in the 1st tooth part 393. Since the 1st tooth part 393 of a moving rack 39 is prevented from being locked because of simultaneous meshing of the 3rd and 5th reducer gears 25, 27 by means of the elasticity of the nothc part 397, overload to a motor 21 is prevented. The overload due to simultaneous meshing by delivering the torque of the motor 21 from the 3rd reducer gear 25 and a fixed rack 38 to the tooth part 393 of the moving rack 39 and the reducer gear 27 is prevented and smoother operation is attained. |
