| 摘要 |
The frame is in two mirror-image sections on opposite sides of the body-supporting portion. These are coupled together by first and second hinges (10,19). The first of these can be at the rear and top, and the second at the front and bottom. Each frame section can comprise a front bar and a rear one connected by a further one. The latter can be connected by a third hinge to the bottom end of the rear bar and a fourth one to the top end of the front bar. Each hinge can be of limited angular movement, while also forming a nil angle in the folded position.
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