| 摘要 |
<p>An apparatus for both manual and powered operation of the sash of a double hung window, including a drive belt adjacent one side of the sash, a power drive for the belt, and a pulley carried with the sash and engaging the belt. Two ratchets having wheels with oppositely facing inclined teeth and pawls biased into engagement with the wheel of the respective ratchet through a connecting shaft secure the pulley against pivoting in either direction to effectively lock the pulley relative to the engaged belt. A ratchet housing is disposed in a sash recess and has a D-shaped opening on one end adjacent a cylindrical opening to the pulley. A bushing for the ratchet shaft is received in the sash cylindrical opening and includes a D-shaped flange receivable through an annular opening in the housing whereby twisting of the bushing. misaligns the flange with a suitable tab to secure the bushing in the sash cylindrical opening. A manually graspable sash lift extends into the housing and when manually biased is movable a limited amount relative to the sash whereby the pawl of the ratchet which secures the pulley against pivoting in the direction required to allow the sash to move relative to the belt in the direction of the manual bias is disengaged from the ratchet wheel. The sash lift is also manually engageable to laterally move the shaft out of engagement with the pulley so as to permit the sash to be disconnected from the pulley for maintenance.</p> |
