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Geared horizontal twin engine

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  • Geared horizontal twin engine

    I have always thought that the most elegant cross head guides I've ever seen were on the Popcorn engine, as designed a few years ago by Stu Hart of the U.K. Stu done the original in metric, then I took his drawings and basically redrew them in imperial inch size. I changed very little, and it has always been one of my favourite engines. A week or so has gone by since I finished my version of the Trevithick locomotive engine. I'm setting here this morning on my computer dicking around with the idea of a twin horizontal engine that incorporates the Popcorn cross head guides and operates the cylinder slide valves thru a set of gears similar to what I did on the Trevithick engine.
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

  • #2
    This looks like a really cool engine!

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    • #3
      For the sake of symmetry and balance, I'll put a skinny flywheel on each side. The power take offs and the flywheels are both running on the camshaft.
      Brian Rupnow
      Design engineer
      Barrie, Ontario, Canada

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      • #4
        I see why you like the design. It's got a very different look to it. The cut away round turned slideways are particularly attractive as a design variation. And I like how it's clearly intended to be totally produced from bar stock and flat plate.
        Chilliwack BC, Canada

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        • #5
          In order to visualize the overall size, what flywheel diameter were you thinking about?
          I cut it off twice; it's still too short
          Oregon, USA

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          • #6
            5" o.d. flywheels.
            Brian Rupnow
            Design engineer
            Barrie, Ontario, Canada

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            • #7
              Brian Rupnow
              Design engineer
              Barrie, Ontario, Canada

              Comment


              • #8
                Other people have used this gear driven design on single acting hit and miss engines, and it doesn't work well on them. The main reason it doesn't work well on hit and miss engines is that there is such great reversal of torque between when the engines hit to drive the crankshaft and then the torque reversal when the engine coasts, depending on the inertia of the flywheels to carry the engine thru a number of miss cycles. This plays Hell with the gear teeth. On a double acting two cylinder engine, you really don't even need much of a flywheel for them to run.
                Brian Rupnow
                Design engineer
                Barrie, Ontario, Canada

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                • #9
                  I can tell I'll want to buy the plans to this engine already.

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                  • #10
                    RB211---That's a good thing!!! I never had any requests for a plan set for the Trevithick engine, and I didn't really think I would. Still, I spent about $200 for materials and spherical rod ends and water-jet cutting. I have far more luck selling plans for engines, and I think this will be a pretty one.---Brian
                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

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                    • #11
                      Brian, I watch your engine builds with interest. Sometimes I wonder if you every design and build one for a practical use, such as an emergency power source that could run from a 1 lb propane cylinder. That idea has been in my head for a long time- I suppose it's more practical to buy a 2000 watt Honda genset, but a 50 watt unit that would live in the trunk of the car would be a great bonus in case of dead battery in the middle of nowhere- as long as you can handle having a full can of propane sitting there patiently as well. What I'm thinking of is a little 2 cylinder unit whos crankcase would screw right onto the cylinder.

                      I'm not trying to take anything away from your creativity with your various engines- just wondering if there's ever been any interest in doing something like this.
                      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                      • #12
                        No, I've never thought of something like that. I spent an entire lifetime designing machines and automation for industry, ranging from very modest weld and assembly fixtures up to machines the size of excavators. I've worked for and with a number of inventors, but I don't think any of them got rich from their inventions. Now the stuff I design is for my own amusement. I'm quite sure that if you used the correct search terms on Google, you will find that someone has already designed and patented what you are talking about. Actually, that happens a lot. People come to me with great ideas looking for patent drawings, I sign a non-disclosure agreement, and then when I hear about their idea I can generally find it on the internet, already designed, patented, and marketed.---Brian
                        Brian Rupnow
                        Design engineer
                        Barrie, Ontario, Canada

                        Comment


                        • #13
                          This morning I'm making gear blanks from steel. Whenever I buy a length of steel, I always buy it 2" or 3" longer than I actually need. All of the left over pieces are saved for jobs exactly like this. A lot of left over short pieces of shafting end up becoming gears for different projects. I'm not down to "zero scrap", but I try to use up every possible bit of steel that I buy. The o.d. of the gear, the o.d. of the hubs, and the bore are all put in in this set-up. Then I will flip the part around in the jaws and turn down the remaining bit to the outer diameter of the hub. This gives me a portion of steel to hold in my 3 jaw vice mounted on my rotary table when I cut the teeth into the blank. Then the extra long hub will be shortened to size.
                          Brian Rupnow
                          Design engineer
                          Barrie, Ontario, Canada

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                          • #14
                            That's enough work for today. Both gear blanks are turned to size, and the main crankshaft support is roughed out. I have had a clever idea about cutting teeth in the gear blanks, but I will share that with you tomorrow.
                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

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                            • #15
                              This morning I cut the 36 tooth gears. Yesterday, as you seen, the gear blanks were made from two different pieces of steel. I wanted to cut these gear one time only. The gear in the chuck has an extended hub on one side which is held in the chuck jaws. Both gears have been drilled and tapped for set screws and will eventually get keyways cut directly below the set screws. I inserted a piece of 3/8" cold rolled steel into the gear in the chuck, and that same piece of cold rolled extends thru the second gear, and on out to the tailstock chuck. Set screws are firmly cinched up on both gears, and this lets me cut both gears in one pass. This only works if both gears have the same number of teeth. Now I will trim the hubs on both gears to the finished dimension and add the keyways.
                              Brian Rupnow
                              Design engineer
                              Barrie, Ontario, Canada

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