| 摘要 |
<p>The wheelchair attachment has two pairs of supplementary wheels which are mounted at the front and rear. Four hydraulic jacks are installed symmetrically and are driven independently by pumps operated by the user of the chair. The front and rear supplementary wheels are connected to the chair by pivoting arms and may be raised and lowered by the jacks. When the front wheels are on an upper step or kerb, the rear wheels are driven by an endless chain to move the chair up the kerb while being supported by the front wheels.</p> |
