| 摘要 |
<p>The device for tightening plastics sheeting over a roof, such as one belonging to a greenhouse, consists of a number of tubular guides (3) connecting one of the fixed end trusses (2d) to the adjacent truss (2c). A mobile truss (4) moves along the guides (3) by means of slide pieces (5) which can be locked in position on the guides (3) by means of fixtures such as screws (6). The mobile truss (4) consists of a U-shaped section (7) with the plastics sheeting (F) fixed in the hollow if the U(7) by means of a flat section (8) which can be bolted on . The sheeting can also be attached to the roof cross-ties (1a, 1b) by means of fillets (9). Detachable tension-pieces (10) pull the mobile truss (4) towards the end truss (2d).</p> |
