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  • Looking at the engine in the drawing, the valve rod and eccentric rod are in a straight line it that position. Moving the reverse lever to the other position should put the other eccentric rod in the same relationship to the valve rod. If so, all is OK.

    Since you have already set up the engine to run, you have the setting basics correct. The eccentrics should be at 120* separation at BDC. Decide what is forward, and set the engine to run in that direction with one set of eccentrics. The engine should run in reverse with no further adjustment if all is correct by moving the reversing lever.

    You will need a detent or some other means of retaining the lever in the reverse and forward positions to prevent it from vibrating out of position.
    Jim H.

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    • Thank you gentlemen-My knowledge of steam engine valve setting so far, extends to the eccentric position relative to the crankshaft and the slide valve relative to it's position in the steamchest. The "throw" of the eccentric should be equal to 1/4 of the "throw" on the crankshaft. My crankshaft has a "throw" of 3/8" (which gives a total stroke of 3/4"). The "throw" on my eccentric is .094" which gives the slide valve a total travel of .188" . When the piston is at bottom dead center, the eccentric lobe should be half way thru it's highest and lowest points of travel (that is how you position the eccentric rotationally in respect to the crankshaft. Also, at this time and position, the slide valve should be exactly half way thru it's full travel (3/16") in the steamchest. This method has always worked well for me. The set up for reversing apparently follows exactly the same procedure when setting up with the straight rod directly below the valve rod vertically. When the reversing handle is rotated thru 30 degrees, this brings the offset rod into position directly below the valve rod and hopefully makes the engine run in reverse. I think I've got it, but will only know when I have everything reassembled. I'm a bit unclear what happens at the other cylinder, as the crankshaft is 90 degrees "out of phase" yet is still connected to the same reversing lever.
      Last edited by brian Rupnow; 11-13-2017, 10:59 AM.
      Brian Rupnow

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      • Here is a short video of me practicing my Canadian Newfie accent and demonstrating the working of my first stage of reversing mechanism.
        https://www.youtube.com/watch?v=d2UiP4gDUKE
        Brian Rupnow

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        • Actually, the throw of the valve eccentric is not really directly related to the crankshaft throw, but clearly directly related to the valve dimensions. The valve has to move the distance required to cover and uncover the steam ports and exhaust port, and the eccentric needs to be able to move it that far.

          Presumably, the dimensions you have used do that, since the engine runs.

          When moved to reverse, the valves should occupy the positions they need to for the piston positions of both cylinders in the new direction. So a piston at half stroke would essentially have the valve position reversed so that steam is admitted to the opposite side of the piston, etc, neglecting any issues of cutoff, etc. If the piston is near one end of the stroke, then the same reversal of sides occurs, with the side that was closing on exhaust being reset to be opening to steam.

          It should not matter which cylinder is being considered, both should be set to the conditions for the opposite rotation when reversed. This should be automatic if the eccentrics are set properly for each direction.
          1601

          Keep eye on ball.
          Hashim Khan

          Comment


          • Originally posted by brian Rupnow View Post
            Here is a short video of me practicing my Canadian Newfie accent and demonstrating the working of my first stage of reversing mechanism.
            https://www.youtube.com/watch?v=d2UiP4gDUKE
            Very nice drill bit holder

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            • A gentleman on a different forum has shown me the error of my ways. It isindeed correct that the stroke of the steam valve is what determines the "throw" on the eccentric, and is not directly related to the "throw" of the crankshaft. I'm sure that there is some esoteric science that explains why steamchests would be longer or shorter, requiring a greater or lesser "stroke" of the steam valve, but it is a road I don't really want to go down right now. As far as "lap" and "lead" are concerned, I have a glimmer of why this would be so, as it relates to internal combustion engines where the valves don't open and close when the piston is exactly at top or bottom dead center. I have always set my model "steam" engines up with the steam valve positioned exactly in the center of it's travel when the piston is either at top or bottom dead center, and that has always worked for me. I will let you know how that works out with this engine.---Brian
              Brian Rupnow

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              • A short video of the complete Stephensons reversing linkage on my engine.
                https://www.youtube.com/watch?v=84W3HiL-je4
                Brian Rupnow

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                • AWRIGHT!!! We've-got foreword and reverse working on one cylinder. Hooray Hooray---Happy Dance. What a wrestle!--Spent a very large portion of today (with help from numerous others) getting the valve adjusted. Hope the other side goes a bit easier.
                  Last edited by brian Rupnow; 11-15-2017, 07:24 PM.
                  Brian Rupnow

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                  • Great news Brian , still following here when i get the chance!

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                    • Progress report. I have everything back together but the cylinder closest to the flywheel is still acting quite wimpy. I need a break from this before I break out in hives!!! I have to go across town now and do some business, and maybe when I get home later I can try a teensy bit of adjusting on the eccentric on that underperforming side. If I'm really, really lucky, that may be all it takes. Hope--hope.
                      Brian Rupnow

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                      • Today we had success. The engine ran on both cylinders, forward and then reverse. It's not video worthy yet, but it certainly made my old heart go pitter patter. I had a tough time getting the eccentrics set in the correct position on the second cylinder. I could get it to run, but only clockwise. then I would adjust it a little bit and it would only run counterclockwise. Finally, I played "Around the clock" and moved it in 20 degree increments until I found the sweet spot, where it would run in either direction as dictated by the reversing levers position and in concert with the first cylinder. At the end of the day I scrounged around in my shop until I found a piece of steel to make a second flywheel. I'm not sure if I actually need it or not, but even if I only use it during "set-up" procedures you can never have too many extra flywheels around.
                        Brian Rupnow

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                        • Okay kiddies--Here we go!! A running and reversing, all bar stock engine. Thank you so much to all of the forum members who stepped up and offered assistance when I was trying to figure out how to make the reversing mechanism work. Someone please give me a heads up if you can see the video alright.---Brian
                          https://www.youtube.com/watch?v=t-oKiCXyFyE
                          Brian Rupnow

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                          • Video works fine Brian. Nice job on the engine. Very cool. Thanks for showing it, and keeping up the build thread. It's nice to see something come alive from a pile of material.

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                            • In order to cover some of my cost of materials in this build, I will exchange a complete set of my drawings for a $25 Canadian donation.
                              Brian Rupnow

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                              • Great job Brian. Nice to see it run both ways. Thanks for sharing.
                                Glenn Bird

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