| 摘要 |
An improved spring balancer (10) includes a shaft (13) rotatably mounted on a support (11). A first torsional spring (14) acts between the support and the shaft. A second torsional spring (19) acts between the support and a cable drum assembly (63) journalled on the shaft. A third spring (23) acts between the support and another cable drum assembly (26). A fourth cable drum (28) is fixed to the shaft. Four cables (141,142,143,144) are associated with the various cable drums (140,63,26,28) and are connected to a roll-up door (12). When the door is lowered, the various springs will absorb energy. When the door is raised, the various springs will give up energy. |
