His eye went up, along the duckcloth drive belt to the line shaft running along the ceiling. That was an obsolete drive system, at least on Earth; at the same time, he’d always wondered if there was an advantage to it that had been forgotten. Instead of each machine having its own drive motor, one single larger motor could be used for everything. The dust collection system in his machine shop was a common system, running to all machines and powered by one motor, so why had people gone away from that? Besides the obvious danger of getting caught in a rotating shaft; but then practically everything in the machine shop involved rotating shafts, and all the machines had ample safeties to mitigate carelessness or stupidity.