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- Nov 25, 2015
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Must have missed this post earlier... Thanks for posting it Glenn, looks quite modern for it's early days. Quite inviting too.
That was my bit of trivia. The belts are laced on each end and held together with a pin. When the tension was released off the drive belt the machinist or operator, whatever the machine happened to be, had a pole with a hook which they could use to slip the belt off the line shaft pulley. They would pull the pin, then twist the belt and pull it around the opposite side of the driven pulley and pin it back together, then slip it back on the line shaft pulley. I can imagine if they were cutting left hand threads they had machines set to do this, because this seems labor intensive. It's interesting to see what happened to get the job done.Yep, there must be some way to reverse direction with the belt drive system, but darned if I know how to do it.
Nearly always, lathes of the line shaft drive type had a countershaft above with two clutches and a cone pulley on it; one clutch was driven by an open belt, the other a crossed belt for reverse rotation and a wooden lever to actuate either clutch; this was about always true on lathes with a lead screw for threading, as not all had a thread dial, and you had to reverse the lathe for threading to return the tool it its starting point for the subsequent cut. I have seen only one lathe, probably from the civil war era that was not so equipped; on it, the screw was used only for feeding, there being no provision for change gears, on it, the countershaft had only a tight and loose pulley for stop/start in the forward direction, It is nearly impossible to cross a belt as described above that was "open", as the belt would be too short, unless there was some provision to shorten the center distance. My first shop when I went into business in 1973 was mostly line shaft driven; when I had to relocate in the early 1980s it all went away due to the modern metal building that I moved into; some of the machines were converted, some replaced over time; when I sold out about 6 years ago, I was up to an average machinery age of perhaps WW-2 for the most part, and my home shop is nearly all 1940s and 1950s machinery.That was my bit of trivia. The belts are laced on each end and held together with a pin. When the tension was released off the drive belt the machinist or operator, whatever the machine happened to be, had a pole with a hook which they could use to slip the belt off the line shaft pulley. They would pull the pin, then twist the belt and pull it around the opposite side of the driven pulley and pin it back together, then slip it back on the line shaft pulley. I can imagine if they were cutting left hand threads they had machines set to do this, because this seems labor intensive. It's interesting to see what happened to get the job done.
Some of the vintage lathes in the transition period to electric motors still used the flat transition belts. My Lodge and Shipley is older so someone fabricated a contraption, of electric motor, large V-belt pulley that that drives the three step cone which acts as the line shaft. The distance between the upper and lower three step cone is only about 30" and it doesn't have enough slack to twist the belt. For it to work (maybe) I would need to get a belt slightly longer just to use for reverse but I'm still not sure if there's sufficient space for the twist.