| 摘要 |
<p>The 'up and over' garage door (2) has counterweight (32,31) assistance with a traction cable (19) pulley wheel (21,22,33) transmission. The effective weight of the counterweight decreases progressively as the door opens, thus, balancing the door weight with greater uniformity during the opening swing. The counterweight descends vertically as the door opens, and may comprise a base weight (32) which supports a stack of separate weights (31). The base weight (32) is attached to the traction cable (19), and the stacked weights have parallel horizontal rails (35,36) on opposite flanks. During the descent of the counterweight the rails ledge on stops (37,38) provide on interspaced guide posts (28).</p> |
