I have a 1942 10EE with a speed reducer. There is a handle on the operator side that connects to linkage that controls the speed reducer.
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Here are photos of the linkage on the lathe and off.
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So, what is this star-wheel thing on the end of the linkage shaft do? I'm guessing that there was some kind of ratchet that mated to it at one time. Anyone have something similar on their lathe and can post a photo? I suspect there are parts missing.
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You are looking at a dual-purpose mechanism with two separate, but related, missions.
The lever arm and outer tube shift the reduction gearbox in or out off a clevis and rod linkage.
That both selects gross speed "range", and sends a visual signal or "flag" by the handle position as to which range is engaged at the moment.
The inner shaft "dials" the speed-control rheostats thru somewhere around 270+ degrees of travel by means of a bicycle-chain drive with step DOWN ratio so the small knob is not so overly touchy as one adjusts it. That selects fine speed within each of the two "ranges" - open-belt or "direct", and geared-down. The tachometer does the rest, as it reads net spindle speed, geared down or not.
That's why the controls were co-located/combined, and the tacho placed in eyeshot. Only one position for a busy hand to reach for.
Step left. Set up spindle sped.
Step right, operate the carriage to remove metal.
It's close enough to change speed whilst in the cut, and 10EE mavins sometimes did exactly that on facing or curved work. Atom bomb cores, we've been told it was automated. Controls had to be remoted, anyway. Radiation and toxicity thing.