A green chain is a type of
lumber
Lumber is wood that has been processed into uniform and useful sizes (dimensional lumber), including beams and planks or boards. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, window frames). ...
delivery system that can be used in a
sawmill
A sawmill (saw mill, saw-mill) or lumber mill is a facility where logging, logs are cut into lumber. Modern sawmills use a motorized saw to cut logs lengthwise to make long pieces, and crosswise to length depending on standard or custom sizes ...
. The green chain's purpose is to collect the final product of the mill and move it at a controlled rate to be graded and sorted.
[''Australian forest industries journal''. vol. 44 Sydney: Australian Forest Industries Journal Pty. Ltd., 1978. 41. Print.] In the 19th and early to late 20th century, the green chain was used by people. Men would stand alongside and pull lumber that matches the required dimensions and place it in piles. In short, the workers sorted the lumber. Modern
sawmill
A sawmill (saw mill, saw-mill) or lumber mill is a facility where logging, logs are cut into lumber. Modern sawmills use a motorized saw to cut logs lengthwise to make long pieces, and crosswise to length depending on standard or custom sizes ...
s use automatic systems, such as the lumber dropping through the chain into large slings, where it can be picked up and moved to a staging area to dry. Most likely called the green chain because the lumber is green and has not been seasoned.
References
Sawmill technology
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