| 摘要 |
<p>PURPOSE: To eliminate sewage sump from a universal joint installed at a small diameter manhole made of polyvinyl chloride in single piece structure. CONSTITUTION: A small diameter manhole 11 made of polyvinyl chloride is equipped with an upward facing inspection cylinder, aside facing universal joint for influx pipe, aside facing universal joint for outflow pipe, and aside facing spigot for outflow pipe, wherein universal joint is composed of a spherically concave shell 13, a spherically convex core 19, and an O-ring 18. An influx short pipe 21 is inserted through the core 19, and the spgot side of this short pipe 21 is protruded toward the body 11 of manhole from the spherical part of the shell 13 so as to enclose a sewage sump, and an approx. upper half of the spigot side is notched off to produce a gutter-shaped receptacle 23. This eliminates sewage sump formed by the shell and core, and the receptacle 23 works also as a guide for a cleaning tool etc.</p> |
