| 摘要 |
A counterweight system for an overhead door (10) or like installation includes an elongate flexible belt (29) having a series of weights (33) spaced thereon, the belt (29) being suspended at the side of the door (10) from a cable (34) that passes over a pulley (24) and is attached to the lower end (30) of the door (10), the lower end of the belt being connected to the door frame (23) about halfway in the height of the door such that when the door moves in the opening direction the weights are successively suspended from the fixed attachment point so that the opening force applied to the door accurately counterbalances the effective weight of the door at all points in the opening movement. |
