| 摘要 |
An access device that provides access between a substrate surface and an elevated surface includes a first ladder member that is operatively attached to a mounting via a drive mechanism. The drive mechanism includes a rotatable member having three pivotal connectors spaced apart in a triangular arrangement. A first of the connectors is pivotally attached to the mounting. A second of the connectors is pivotally attached to the first ladder member via a control arm. A third of the connectors is pivotally attached to an extremity of the mounting via an extendible arm. The extendible arm causes the rotatable member to rotate about the first connector, and consequently effect movement of the access device. The access device further includes a second ladder member, a first end of which is pivotally attached to a second end of the first ladder member. |
