| 摘要 |
<p>The shutter which is intended to close rapidly under its own weight when a catch is released electrically could be used in financial establishments to protect staff from being injured or taken hostage during a robber. It consists of a shutter attached to a free roller, the end plate of the shutter being weighted with metal. The shutter is held open in guide rails by a catch which is attached to the end plate by two countersunk screws. The catch rests on the bolt of an electrically operated hook fixed to an angle bar by two countersunk screws.</p> |
