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Thread: Speed control for a 25 hp steam engine.

  1. #1
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    Speed control for a 25 hp steam engine.

    Hi,
    I am constructing a modern 25 hp steam engine (7borex12stroke 150RPM). I need someone to build a simple speed control that will power a 12 volt linear actuator which will operate a 1 1/4" ball valve controlling steam volume. The engine will have an alternator w/battery. A pick-up will be needed to sense RPM (I thought a magnet switch or Momentary on micro or something) . The controller needs two pots, one for the actual rpm setting and the other a sensitivity for delay so the actuator isn't activating for every little change. If a design is made, I can put the board together if need be. The actuator SPECIFICATIONS

    Stroke Nominal 6"
    Voltage 12 DC
    Push/Pull Ratings
    Dynamic 110 lbs. max
    Static 500 lbs. max
    Amps 3.5 Duty 20%
    Avg. Extension Speed 0.5"/sec.



    When a load is placed on the engine, the reduction in rpm is sensed and the steam valve opens allowing more steam pressure to keep rpm with in a range, say + or - 25 rpm.There is a huge flywheel to help with fluctuations. Loads wont change much. Once a load is placed, the load will be constant-A/C generator-water pump-etc.



    Would there be anybody here that can help me?
    Jim

  2. #2
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    Hi Jim,

    Welcome to the forum and I like the idea of a steam engine. Do some research on
    steam engine Watt fly-ball
    steam engine centrifugal speed control
    steam engine centrifugal governor

    That should get you started. It is a purely mechanical thing and it is not called a "Watt" speed control for nothing. The man himself invented it and it has been used largely unchanged since then on about a zillion engines. Also they look really cool in operation.

    A Cautionary note: A steam engine is quite a simple device, but the boiler that delivers the steam under great pressure is not so simple. Please be sure you know what you are doing with the boiler side. I'd suggest buying the boiler.

    Also your local State, County and/or City may require it to be Certified, and they do that for a VERY good reason.

  3. #3
    Lead Engineer RWOLFEJR's Avatar
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    The mechanical governors are really slick. Few Buds and I can watch a hit-n-miss motor run all day...

    And like Dave mentioned be careful about the laws in your area for steam engines. In PA you have to have them inspected every so often to run them. There have been explosions and people killed by the things. My recollection is it's fairly expensive to have a steam engine tested and certified.

  4. #4
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    Right.

    I have been researching this project for almost a year now. Most of the parts I have assembled and I am almost ready to begin machining and construction.Design is all completed but the rpm control system. I am familiar with the various designs on fly-ball governors. Since the engine was going to push an alternator, thought the electronic speed control was worth looking into. It would look nice too. Anybody you know can design the board for me?

  5. #5
    Technical Fellow jboggs's Avatar
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    So, you want to control the speed of a steam engine that will be used to produce electrical current... with electricity? Not sure I understand the logic in that. If that's really what you want to do then I would suggest you buy an electronic speed sensor and an electric linear actuator from any one of hundreds of sources. They come in a WIDE variety and with all the controls you would need to do what you want to do. I would avoid trying to design and build an electronic control circuit when they are already available off the shelf (and already de-bugged!!) at very reasonable prices.

  6. #6
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    I have tried to locate an electronic speed sensor circuit and was unsuccessful. Can you direct me to the right location? I have an actuator. Thanks so much
    Jim

  7. #7
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    Quote Originally Posted by James View Post
    I have tried to locate an electronic speed sensor
    Jim,

    You need a "Govenor," not a "Sensor." Something that will adjust the actuator to maintain a set RPM. About a zillion of them out there.

  8. #8
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    I need some help. I have been trying to locate a governor that will operate a linear actuator for this engine. Can anybody direct me?

  9. #9
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    Quote Originally Posted by James View Post
    I need some help. I have been trying to locate a governor that will operate a linear actuator for this engine. Can anybody direct me?
    What about a cruise control for a car? All you need is something to generate the pulse-train (multi-point cam with magnets and reed-switch) then feed it into the cruise control. You could have it control the valve directly, no actuator needed.

    I still think you are crazy to want an electronic control on a steam engine. Steam is serious stuff and the last thing you want is a run away engine because a battery failed or a wire broke and you can't throttle the steam back until the boiler cools. You have to keep feeding it water to make more steam until the fire goes down to stop making steam.

    I'm gonna fall back to the Thomas Gray theory and make this my last comment in this thread.

  10. #10
    Technical Fellow jboggs's Avatar
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    Go to www.mcmaster.com or www.omega.com and type in "speed sensor". You'll get a bunch of non-contact tachometers, some with electronic output. You can use that signal to control your actuator.

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