| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a reliable changeable joint in diameter for use in information box duct systems that is free from the direct influences of external pressure, such as earth pressure, hydraulic pressure, and vibration, and uses sockets made of vinyl chloride resin. SOLUTION: The changeable joint in diameter comprises a large-diameter short pipe 11 provided at one end with an opening into which the tips of outer pipes are to be inserted and at the other end with a flange 14, a discoidal lid 15 that have through holes in the center and seals the other end of the large- diameter short pipe 11 watertight, small-diameter small pipes 18 that are tightly fit onto the through holes in the discoidal lid 15 and allow metal short pipes 22 to pass through watertight, and sockets 21 that couple the tips of the metal short pipes 22 passed through the small-diameter short pipes 18 with the tips of the internal pipes of the information communication duct. Rubber rings 20 for watertight connection may be installed on the inner walls of the small- diameter short pipes 18 inserted into the discoidal.</p> |
