| 摘要 |
Window controls for controlling large window units to permit the windows to be mechanically raised and lowered for ventilation purposes in a reliable, efficient, and low cost manner. The controls include means for automatically locking the window units against intrusion, when the windows are closed or partially open, and further the window controls are simplified by providing edge mounting frames for the glass only at the top and bottom edges of the glass. In some forms of the invention, where it is desired, the windows can carry automatically positionable screens for screening the vent openings.
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