| 摘要 |
A plumb bob level with a casing having sidewalls rigidly connected together by upper and lower end walls; a bobbin positioned below the upper end wall and having a flexible line wrapped therearound and extending longitudinally within the casing toward the lower end wall, the bobbin being selectively and lockably rotatable to adjust the length of the line; a plumb bob with longitudinal upper and lower end portions and an enlarged midportion therebetween, the upper end portion being secured to the line and the lower end portion having a pointed tip in proximity and alignment with a cross-hair target formed on the lower end wall, the plumb bob being free-swinging for movement in all directions responsive to the angular orientation of the casing with respect to true vertical. The level also has transparent front and rear face plates attached to the casing, with the front plate having several sections which are separately removable and leaving a lower portion of the casing open for grasping of the plumb bob. The casing also has a first and second gusset plates positioned toward the lower end wall and intermediate the plumb bob upper and lower end portions, with apertures sized large enough to prevent free-swinging of the plumb bob during normal usage but small enough to prevent the plumb bob from swinging into contact with the sidewalls or face plates. The gusset plates are transparent and extend between the sidewalls for maintaining the spacing therebetween. Additional gusset plates are also provided between the guide plate and the second gusset plate to maintain the spacing between the sidewalls.
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