| 摘要 |
A roller shutter comprises a rotating drum 11 on which a shutter 10 is wound, a spring 13 mechanism that is tensioned by the drum when the shutter is unwound thereby providing resistance to the unwinding, and a braking member 20 movable from a braking position where rotation of the drum is restricted (fig.2) and a free position (fig. 1), said braking member 20 being linked to said spring 13 mechanism so that tension therein urges the braking member to a free position while a counter-tension member 24 tends to bias the braking member in the opposite direction. During normal operation the drum is not restricted from rotation, but in the event of a failure in the balancing / compensating spring 13, drum rotation is restricted. Braking member 20 may engage brake shoes 21 which engage the drum. The drum is mounted on a spindle 12 which is capable of limited rotation relative to its mounting. |
