I always wondered how much maintenance all of those overhead drive belts required. Did they need daily or weekly attention? Or were they more robust than they appear?
When I worked for Packard Electric, they had several banks of ancient machines called Braiders which braided nylon thread around partially finished spark plug cable before the outer silicone jacket was applied. A bank of ten or twelve Braiders ran off of a large single electric motor which ran a line shaft behind the machines. Each Braider had a 6" wide flat leather belt continuously turning, and a hand clutch engaged the machine to start it. They ran three shifts five days a week, and I never once had to repair or replace a belt during the seven months I worked in that department. The only time they went down was either when an individual Braider had something malfunctioning, or for a few minutes when the operator had to replace near empty spools of thread. The large spools of partially finished spark plug cable held at least 10,000 feet per roll, and these flat leather belts were running the machine and also slowly turning these roughly 5 ft. diameter metal spools of cable as it was fed out, braided, and rewound on another spool. As I recall, I once had to put a leather belt back on the pulleys after it had walked off. But I'd have to say the belts were very robust.
It was odd to see these machines that dated back to the early days of the automotive industry, especially in a plant that had the most state of the art PLC and CNC equipment available. But it was explained to me that nothing better had ever been developed, so they continued to use them, and the only change was going from cotton thread to the nylon thread. Of course, the entire construction of spark plug cable changed considerably over time too, but they still occasionally made small runs of the old non-resistor copper core stuff. Repairing Braiders was pretty mechanically challenging, and parts often had to be scavenged from machines that were no longer used because replacement parts hadn't been made for decades. They really didn't make much noise when they were operating, but they were at the rear of the plant behind a huge wall of sound deadening curtain. I always figured that was done in the hope that an OSHA Inspector wouldn't see them because they had hundreds of exposed moving parts and no equipment guarding around the individual machines, or the motor driven line shaft and flat belting. There was no possible way to lock out a machine for servicing or repair without shutting them all down, but I still have all my fingers so I must have done something right.