| 摘要 |
A spring assembly is provided for an upward acting door that travels on a travel path while opening. The assembly includes a shaft, a torsion spring and a second spring. The torsion spring is connected to the shaft and provides a lifting force for the door throughout the travel path. The second spring is connected to the shaft and provides a lifting force for the door during only a portion of the travel path. In another aspect, a spring assembly is provided for an upward acting door that travels on a travel path while closing. The torsion spring is connected to the shaft and provides a weight supporting force for the door throughout the travel path. The second spring is connected to the shaft and provides a weight supporting force for the door during only a portion of the travel path. |
