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The last indicator card for Sabino that I saw was 75% cut off and just a smidge of lead. I would dispense with the lead on an engine this small. Dave
A Shay locomotive is really just a marine engine that got lost in the woods.
QuoteA Shay locomotive is really just a marine engine that got lost in the woods. Thank you for that laugh Dan Per
Also once you get farther along, can these diagrams predict what effects notching in the Stevenson link does?
Quote from: crueby on April 12, 2022, 04:11:51 AMAlso once you get farther along, can these diagrams predict what effects notching in the Stevenson link does?Chris, good question. The short answer is no in this thread we are designing the steam valve. It could be used for a single eccentric engine or any type of reversing gear.To see what happens by notching back it would be best to use a program like Docksteader to see and compare the output curves.Now when looking at the curves made by Docksteader's program how do you know when you change a variable if the change made the situation better or worse? It took a bit of thinking about that and the best I could come up with was to use the slip eccentric module for the same engine. A slip eccentric simply shifts the eccentric so the engine acts like a single eccentric engine and the curves look like a single eccentric solution. So my theory is if the change makes the reverse gear design look more like the slip eccentric curves then the situation is better and if the curves look less like the slip eccentric curve then you have made things worse.The motor that drives Docksteader's program only goes in one direction so it is possible to turn a steam engine into a compressor by shifting the eccentrics far enough. I have done this and it is weird. (It is a program that is fun to throw a monkey wrench into)The other way to see what happens when by notching back is to make a model. It was common to make a partial engine model to do just that in the days of steam. Now with 3D cad it is even easier to make a full model to see what is up with notching back with Stephenson link motion.Now to get completely long-winded... The most common way to connect the eccentric rods for Stephenson link motion is with open rods. With open rods, the lead increases from full gear to mid gear. With crossed rods the lead decreases from full gear to mid gear. Open rods are the most common way to set up Stephenson gear. It is simple to change to crossed rods by simply shifting both eccentrics by 180 degrees. It would be interesting to check on what happens to the valve positions for both crossed and open rods to see what happens by flipping the eccentrics at several different angles of the crank.Cheers Dan