DIY electronic throttle and gearbox control

Discussion in 'OnBoard Electronics & Controls' started by CDK, Apr 3, 2008.

  1. pistnbroke
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    If you were attach the linear actuator with say an 8 in throw direct to your control column then it would certainly be powerfull enough to move the cables . When I built mine I used two change over relays rather than the bridge and this has proved fine with no failures.You should however remember that rapid movements of the throttle /gear change are often required and I dont think the response is fast enough for emergency or docking.
     
  2. ma5645
    Joined: May 2014
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    Location: canada

    ma5645 New Member

    CDK -
    Thanks a lot for the speedy reply.

    Seems clutches are unavoidable, if I would like to have the mechanical backup.
    Which make the actuator itself a bit more complicated.

    At the same time, I've checked most of the articles from page:
    http://www.marinewaypoints.com/pages/Gear_and_Equipment/Engine_Controls/index.html
    And it looks that only Glendinning Smart Actuator has such option. The rest companies suggest to replace mechanical with electronic controls.

    The mechanical control looks to be simple and reliable...
    In your experience, is electronic control as reliable? ( I assume you are using them a lot).

    Thanks,
    Michael.
     
  3. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    The reason I made the controls was the length of the bowden cables in my boat.
    Electronic control can be just as reliable if properly designed and built, but of course failures cannot be excluded. A few years ago I made an emergency repair for a sailing yacht in our bay. The owner approached the quay to throw a line, then reversed to keep distance, but in that moment a small brass object in the control box crumbled, releasing the bowden cable in neutral position.....
     
  4. pistnbroke
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    pistnbroke I try

    ma5645..I think you are underestimating the speed at which these linear servos operate which even CDK has described as slow and very slow..just a thought ..I think its a saftey issue. your funeral as they say.
     
  5. ma5645
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    ma5645 New Member

    Thanks for replies.

    Speaking about the servo speed. Is it a limitation of those particular servos, used in assembly?

    I've found some info on 'commercial product' like:
    http://www.glendinningprods.com/products/engine-controls/mechanical/177-smart-actuator
    http://www.youtube.com/watch?v=EfiMDPGmqiQ

    It looks like speed is not the issue on that unit. ( Saying that it is quite possible it is an 'illusion of utube', and on practice it is still slow). I wonder if somebody has seen those units in real life, and has first hand experience.

    At this point I'm trying 'to estimate' if it is possible to make the mechanical part reliable and practical to assist during single handed docking. ( I'm confident to be able to make a proper electronics, with remote, etc. But designing and assembling the mechanical actuator is not the area of my expertise ).
    To this end, your comments about the speed of operation is very valuable.

    Thanks again,
    Michael.
     
  6. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    Quite a different approach is something I found in the emission control system of my Fiat Ducato van.
    They use a throttle valve (strange item in a diesel!) powered with something the manual says is an electric motor, but disassembly showed it is just a rotating solenoid with permanent magnets and a coil. The valve is kept open by a spiral spring, the actuator on the same shaft closes it by turning the shaft 90 degrees.

    Under certain driving conditions a pulse width modulated signal (approx. 140 cps) partially closes the valve to create a vacuum that allows exhaust gas to return to the intake manifold. I have not been able to observe it functioning because the PWM signal is only present when the engine is loaded and above 2500 rpm, but it seems capable of maintaining any throttle valve angle between 0 and 90 degrees.
     
  7. thudpucker
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    thudpucker Senior Member

    That was a nice Write up CDK.
    What closes the throttle valve in an emergency?

    In the case of a Rudder control, I'd want the Rudder actuator and the GPS or Course control to be monitored to prevent any sudden Rash movement of the rudder while under way.

    Typing this question I realized this sophisticated system needs more than one talented guy around a table, casting thoughts and the others analyzing for error in the thought.
     
  8. CDK
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    CDK retired engineer

    For quick shutdown a DC signal closes the valve until no rpm is sensed. This at first sounded ridiculous to me, but it seems the oil pan gases contain enough fuel to keep the engine idling for 10-15 seconds. It would not bother me at all, but since the valve is there anyhow, the manufacturer added this little gimmick.

    There seem so be other conditions as well, like a turbo charger overrun and a triggered airbag that close the valve.
     
  9. thudpucker
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    thudpucker Senior Member

    Lot's of good thinking went into that engine your talking about.

    I was reminded of the Sub Chaser from WWII. With a Stack of pillows right by the intake, in case the engine 'ran-away' burning the oil out of the crankcase.
     
  10. willisworms
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    willisworms Junior Member

    Hello all!, I have been spending a lot of time reading this thread and working on my own plan for an electronic shift system for my boat. I own a 1975 Fiberform Executive 28' and the cables are in need of replacement. I have already rebuilt the outdrives which are circa 1975 mercruiser pre alpha. The Legs are in top form and the lower shift cables are brand new. I plan on using feedback actuators attached to short Bowden cables to shift the boat along the lines of CDK (Thank you CDK) My question at this time is how much force does it take to shift a mercruiser outdrive directly at the cable. I would of course like to use the fastest actuator I could.
     
  11. CDK
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    CDK retired engineer

    The forces are small, certainly less than 8 lbs will be enough to compensate for the friction in the cable and the shift mechanism. To avoid excessive wear of the clutches, there must be a short spring between the actuator and the shift cable to allow the ignition cutout switch to do its job.
     
  12. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    Spring balance to be sure
     
  13. willisworms
    Joined: Mar 2016
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    Location: Kelowna, British Columbia, Canada

    willisworms Junior Member

    Thank you for the replies. In Order to keep my initial post short and clear on my intended question I see now that I was a little unclear on my plan. I have ordered two ( I have two engines ) 10' mercury tfxtreme cables. The cables will connect to the shift plate as usual so the spring and interrupt on the shift plate will remain intact. The other side of the cable will attach to the actuator. The lower shift cable will also remain in the stock configuration.

    So the actuator will shift the outdrive through the shift plate as usual.

    I ordered the 10' cables because I would like to keep the actuators inside the cabin and away from any possible water. The electronics will be beside the actuators also inside the cabin.

    I am glad you guys confirmed my belief that the shift pressure is low, I was up late last night on the google monster and found two 35lb feedback actuators at a good price and bought them.

    At 35lbs the actuator moves at 1.7 inches per second. That should mean that it will shift the boat from neutral to in gear in under a second, and from forward to reverse in under 2.

    I am a Millwright by trade, not an electronics guy. I can run wires and terminate them quite well. I can fabricate pretty much anything. But I will need to hire someone for the electronic side of this project. As hard as I have tried to grasp what goes on in an electrical circuit and how to build them, It appears that side of my brain is occupied by all the lyrics to the Gilligans Island theme.

    To keep this thread a little lively, here is a pic of the boat this system will operate
     

    Attached Files:

  14. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    I substituted two relays for the swithing transistors as I think its more reliable otherwise the circiuit works great.
     

  15. willisworms
    Joined: Mar 2016
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    Location: Kelowna, British Columbia, Canada

    willisworms Junior Member

    Thanks for all the info guys! of the few circuit diagrams referred to in this thread, Which one is the best solution for my shifting? I am not going to tackle the throttles at this time, But would like to after I get the shifting sorted.
     
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