| 摘要 |
The duct is held by threaded bolts on bridge railing via a support bracket of 2 mm thick sheet metal is four times edged and holds the duct top and lower parts together by inwards edge. The duct lower part of 1.5mm thick sheet metal is four times edged and retains the telecommunication cable. The duct cover is of 1.5mm thick sheet metal and encloses the duct by engagement of the support bracket and by action of a closure bracket of 5mm thick flat steel for cover engagement and release by a closure screw.
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