My first job out of college 40 years ago was in a chain works, in York, PA. Two multi-story brick buildings, oil soaked wood floors, and line shafts overhead to drive the hundreds of chain forming and chain welding machines. The guys had special wooden "flippers" they used to pop the spinning belts on and off the machine's pulleys. Quite something to see. What a hellish environment to work in though- smoke from the welding machines, "boomalacka zoomalacka" clatter, and fork lifts (gasoline powered) zooming around. (You could see the wood floors rippling overhead as forklifts moved about on the floor above you.) I supervised a tool room some distance away from all that, and God did I hate having to go over there!
