| 摘要 |
In one of several embodiments, a staircase has parallel metal rails 12, 14 attached to a wooden string 10. Angle section tread supports 16 are pivotably attached between the rails 12, 14 to form a parallelogram linkage. Before the rails 12, 14 are secured to the string 10, therefore, the parallelogram linkage permits adjustment of the angle of inclination of the staircase while still maintaining the tread supports 16 horizontal. This enables the staircase to fit stairwells constructed with wider tolerances than hitherto. Once the rails 12, 14 have been secured, treads 32 are affixed between opposing tread supports 16, and risers 52 are fitted. In other embodiments, the steps may be used, collapsed, as a sledge, or, with attached wheels, as a trolley; or, with vertical rails and horizontal treads, as shelving. <IMAGE> |
