| 摘要 |
<p>An access tower has two side parts (1,2) extending from a base part (3) to a top part (4) and inclined cross parts (22-24) each extending from one side part to the other. The rigid cross parts (22-24) are arranged one above another and inclined in opposite senses. The lower one of two successive oppositely inclined cross parts (22,23) has its upper end connected to an articulation node (28) to which the lower end of the upper one is connected. A section (2a) of the side part opposite the articulation node (28) is collapsible so that the upper cross part (23) together with the portion of the tower above it can be lowered into a position in which it extends substantially parallel to the lower cross part (22). The lower end of a further inclined cross part (24) is connected to a further articulation node (32) to which the upper end of the upper inclined cross part (23) is connected. A section (1b) of the side part opposite the further articulation node (32) is collapsible so that the further inclined cross part (24) together with the portion of the tower above it can be lowered into a position in which it extends substantially parallel to the upper inclined cross part (23). Releasable locking devices prevent collapse of the collapsible sections (2a, 1b). A parallelogram mechanism (23,27,31) links the further inclined cross part (24) and the lower inclined cross part (22) so that they remain substantially parallel to each other as the further inclined cross part (24) and upper inclined cross part (23) are lowered and raised.</p> |
