Abstract: A closure apparatus for closing an opening in a partition with a frame disposed around the opening includes a drum member rotatably mounted to the partition at the top end of the opening. It also includes a curtain member secured to the drum member. The curtain member winds around the drum member to move out of the opening in the partition; and it extends from the drum member to close the opening. A counterweight connected to the drum member offsets the weight of the curtain member; and a reducing weight reduces the weight of the counterweight to allow the curtain member to drop from a raised position. An activating assembly engages the reducing weight with the counterweight and allows the curtain member to unwind from the drum member and close the opening.

Abstract: A torsion spring assembly for counterbalancing overhead doors which includes an elongated helical torsion spring with coils that are normally spaced apart (when the spring is untensioned), a shaft extending through the spring, and a pair of spring-mounting collars carried by the shaft and provided with slotted neck portions operatively connected to pre-formed hooks at the ends of the spring. One of the collars is fixed against both rotational and axial movement upon the shaft; the other is rotatably mounted upon the shaft; and at least one of the collars is removable from the shaft for field disassembly and reassembly of the parts. The method for constructing the assembly, either during manufacture or in the field, is also disclosed.