| 摘要 |
PURPOSE:To roll an upper bracket smoothly up and down by bearing the tip portion of the upper bracket through an eccentric collar and a bearing on a shaft projecting from a screw nut in the direction perpendicular with the direction of linear motion of the screw caused by operation of a motor. CONSTITUTION:When a motor is turned ON and a drive shaft 14 is rotated, a screw nut 15 to be screwed over the drive shaft 14 is moved linearly in axial direction. An upper bracket 18 having tip portions born on the shafts 16, 17 projecting perpendicularly with the direction of linear motion rolls around a shaft 19 provided on a tilt bracket 10. Although the tip portion of the upper bracket 18 tries to rotate along an arch having radius R, bearings 20, 21 rotate such that eccentric collars 23 fixed to respective shafts 16, 17 come on an arch having radius of R and center coinciding with the center of the inner ring of a bearing 21, and thereby the upper bracket 18 rollers smoothly. |
