| 摘要 |
A sliding box for placing a film of insulating or draining material within a trench has a front section for receiving a roll of film and a rear section for delivery of the film into the trench. Between the front section (2) and the rear section (13), the box has a connecting chamber (4) provided at each end with a pair of rollers (5-6, 7-8) mounted within said chamber by means for varying the lateral spacing of the rollers of one and the same pair between an active position in which the two rollers grip the film (3) and a position of relative withdrawal in which the film passes freely between the rollers.
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