| 摘要 |
<p>Modifications in a levelling device for ladders and the like are provided. Apertured lug, adapted for attachment to the bottom ends of uprights, stiles or legs of a ladder, trestle, etc., are slidably mounted on an arcuate support bar, and biased to a nonlocking or freely slidable position. On application of weight to the ladder, the apertured lugs pivot to a locking position. In one embodiment, each of the apertured lugs is formed with extension members or fingers with abutment surfaces extending parallel to the plane of the ladder which tangentially engage the sides of the support bar when the apertured lugs are in locked position to prevent or limit any tiltable movement of the support bar out of the plane of the ladder. In another aspect of the invention, the lugs are provided with non-circular apertures and the support bar is formed with a complementary non-circular cross-sectional configuration, such as triangular, square, etc., which configurations prevent rotation of each apertured lug around the support bar, and thus prevent or limit tilting of the support bar out of the plane of the ladder. The levelling device of the present invention may be used on any number of different sizes of ladder to provide stable and safe levelling of the ladder.</p> |
