Rolling steel door

Claim 1

An improved rolling steel door of the type having a plurality of interlocking steel slats, each such slat except for a top slat and a bottom slat having an adjacent superior slat and an adjacent inferior slat and a first end and a second end and each such interlocking slat having an upper curved channel and a lower curved portion, the upper curved channel surrounds the lower curved portion of the adjacent superior channel and the lower curved portion thereof holds the upper curved channel of the inferior slat, said plurality of slats forming a curtain supported at the top slat by a spring-tensioned rotatable barrel assembly including a spring assembly and said curtain being supported along each side by a channel so that the turning of the rotatable barrel raises and lowers the curtain wherein the improvement comprises: said barrel assembly having an outer cylinder to which the rolling steel door is affixed and said outer cylinder having an inner surface and said barrel assembly having an inner spring-containing assembly held within a single inner cylinder having an outside diameter slightly less than the inside diameter of the outer cylinder and having an outer surface which is adjacent the inner surface of the outer cylinder, said inner cylinder extending long a majority of the length of the outer cylinder, said inner cylinder being readily removable from the outer cylinder whereby the spring assembly may be replaced with a minimum of disassembling of the door.