| 摘要 |
<p>The base consists of a series of transverse bars (4), connected at their ends to a rigid frame (3) by couplings (5) which have apertures to receive the ends of the bars and supporting arms (7) beneath which have their lower ends terminating in meshing wheels or toothed segments. Each wheel or segment has a central hole (10) to receive the end of a rigid rod (11) which connects the couplings on opposite ends of the bars. The tips of the rigid rods are connected to the rigid frame by bearings or rings and springs (12). The bar end couplings are made from a semi-rigid plastics with a high degree of elastic memory, while the rigid rods connecting them are of square cross-section. The base can be made, for example, in articulated sections, with a fixed horizontal section and an adjustable back rest. <IMAGE></p> |
