摘要 |
The top and bottom of each upright (1) is joined to a corner link (33) of the substructure (3) and to a corner element (11) of the side-rest (2). The four side rests are joined by a link mechanism (20) which has an inverted-U shaped main body. The substructure consists of four side bars (31), middle bars (32), corner links and one middle link (35). A slide piece (26) fitting into a recess on the main body is fixed to the main body. Each side bar consists of two struts (311) joined by a side link (34) and to the corner link. An opening (341,331) is at the join between the side link and strut and at the join between the corner link and strut respectively.
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