| 摘要 |
Apparatus, to be movably and releasably secured to an inclined or vertical surface, having a rigid framework having two pairs of axially mounted vertically spaced-apart horizontal wheels horizontally spaced-apart on a framework, an endless track mounted on the wheels having linked track members, with each track member having a cavity adapted to press against said surface and be secured thereto by a vacuum in the cavity, an open space within the framework and wheels, a flexible conduit extending from the cavity of each track member into the framework open space and to a vacuum valving means for selectively creating and maintaining a vacuum between the track member and the surface when in contact therewith, and means to drive the wheels to thereby effect crawling of the track as it is held by vacuum on the surface. |
