| 摘要 |
A staircase having adjustable treads comprises two strings (11) which are rigidly connected to each other and between which a number of treads (16-19) are provided. Each tread is at its ends pivotally mounted on a bearing shaft (25-28) in the adjacent string and is connected to a link arm (29-32), the link arm being connected to an adjustable link means (33). The link means can be adjusted by means of an operating arm (20) in such a way that the treads are turned around their bearing shafts, maintaining the upper surfaces of the treads in parallel, so that the angle between the upper surfaces of the treads and the longitudinal direction of the strings is changed. The treads (16-19) can also be turned to a common plane, so that the treads form a substantially continuous, plain surface. By adjustment of the treads, the treads can be positioned substantially horizontally irrespective of the inclination of the strings to the ground plane, so that the staircase is comfortable to use. Alternatively, the treads can form a plain surface, so that the straircase can be used as a ramp, e.g. for transport vehicles or wheeled chairs. |
