| 摘要 |
Comprises a body (7) defining:
- a converging-diverging double-funnel assembly (8) connected to a guide (6) through which it moves a cam follower (12) joined to an arm (13) assembled on a load bar (5) fixed to a piece of canvas (1);
- a retention assembly (9) to retain the cam follower (12) with said piece of canvas (1) under tension in a partially or fully extended position;
- an interlock cam guide (10) and an escape cam guide (11) to respectively lead, following a descending-ascending path, the cam follower (12) from the double-funnel assembly (8) to said retention assembly (9) and vice versa,
said retention assembly (9) comprising a detachable retainer (54) blocking a freeing passage (55) arranged to lead the cam follower (12) directly from the retention assembly (9) to the double-funnel assembly (8) without following said descending-ascending path.
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