| 摘要 |
The invention provides a double hung window assembly having a perimeter frame assembly and a vertically slidable upper sash releasably connected in its raised or closed position by fusible link means to the frame assembly. The vertically slidable bottom sash has releasable catch means for holding it in its lowered or closed position. Stop means adapted to prevent the upper sash moving beyond the lower sash is present. Biasing means are included with the bottom sash to provide an elevated bias to it, sufficient to hold the bottom sash in selected open or raised positions but insufficient to hold both the upper and lower sashes in an elevated position upon release of the fusible link whereby when the assembly is used and when the upper sash is in an elevated position and said retaining means is released, said upper sash will fall until acted upon by said stop means and if said lower sash is raised, both sashes will move to the bottom of said frame assembly leaving a smoke ventilating opening thereabove. |
