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Author Topic: Air throttle - Regulator or no?  (Read 853 times)
TexasBorderDude
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« on: November 07, 2013, 07:00:38 AM »

I have run my 8V71N with an air throttle without a regulator for about 5 years.  Seems fine, but some use a pressure regulator.  What are the pluses and minuses of using an air regulator and what regulated pressure is used?
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« Reply #1 on: November 07, 2013, 08:52:31 AM »

According to Williams Controls the regulator will make the diaphragms live longer.  They are rated for 75psi.

Don and Cary
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« Reply #2 on: November 07, 2013, 09:20:16 AM »

Logically the regulator will make the throttle response more consistent.  The actuator will move a certain amount based on the amount of air pressure, but the pedal will send a percentage of the supply pressure for a given amount of movement.  If the supply pressure varies by 20% up or down, the amount sent will also vary.  It's the sort of thing you can measure easily but that you probably automatically accommodate while you are driving.

Brian
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« Reply #3 on: November 07, 2013, 02:53:55 PM »

So that's the reason my speed drops off when I use the hand throttle, it's caused by the slow drop in air pressure! Learn something new every day!
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Oonrahnjay
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« Reply #4 on: November 07, 2013, 07:24:04 PM »

      My air throttle is very "touchy" but I think that that's mostly in the linkage at the fuel injection pump.  I don't have a regulator but I think it's a good idea and I'm going to install one.  The Williams literature for my assemblies say that they work fine with a pressure of 30 pounds but I'm gonna guess that that's too low a pressure in practice.  Is 65 psi a good level? 
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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

(New Email -- brucebearnc@ (theGoogle gmail place) .com)
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« Reply #5 on: November 08, 2013, 05:33:42 AM »

 Williams air throttles are very touchy when trying trying to control the smoke factor on DD the pedal has to match the control cylinder springs the linkage has to be just right once all the stars are inline they work

Eagles are the worst because you have to use a universal controller because there is not enough room on the top of the governor to use the DD controller 
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Oonrahnjay
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« Reply #6 on: November 08, 2013, 06:35:34 AM »

   Williams air throttles are very touchy when trying trying to control the smoke factor on DD the pedal has to match the control cylinder springs the linkage has to be just right once all the stars are inline they work

Eagles are the worst because you have to use a universal controller because there is not enough room on the top of the governor to use the DD controller 

     Thanks, Clifford.  That's a good thing to know.  I am not sure exactly what I have -- plus, it's located on a fuel pump for a six-cylinder four-stroke diesel with a control pivot arm that I fabricated.  I bought these parts used from "Nimco" when they were in the business of selling used parts and there was no info with them -- I was amazed when I clicked the part numbers stamped on them into Google and the tech specs from Williams popped up.  Unfortunately, those tech specs don't tell exactly what vehicles/engines etc. that the paired assemblies were made for.

      However, the system works very quickly and cleanly.  I haven't noticed any problems with the system at all, except I have 100% of control arm movement at the fuel injection pump when the pedal has been pressed about 30% of the way.  After that, it doesn't matter -- until you let off the pedal, you keep 100%.  It never feel like a problem; when you want to go, you press the pedal, when you want to slow down, you let off the pedal -- but, as I said, it's touchy feeling.  And it will probably feel more comfortable to drive if the touchiness if reduced.

     I think that what i need to do is change the control arm geometry to better make use of the pushrod extension from the air engine cylinder and drop the pressure.  I'm not sure that running 120 or so pounds of pressure makes much difference to the response but it seems likely that lowering the pressure is good for the long-term reliability of the system and it just might help with the issues of the touchiness.
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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

(New Email -- brucebearnc@ (theGoogle gmail place) .com)
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« Reply #7 on: November 08, 2013, 06:48:49 AM »

That is exactly the problem Doyle has Bruce when he gives it throttle it goes to 100% throttle then comes back down 
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TexasBorderDude
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« Reply #8 on: November 08, 2013, 07:01:30 AM »

Yep, Clifford and I noticed some "slop" in the linkage which was probably requiring full throttle to get the slop out.  Just too many damn variables, but I'll work through it thanks to your help and others!
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« Reply #9 on: November 08, 2013, 07:12:38 AM »

Williams recommends a throttle delay to work with the air throttle on the 2 strokes to prevent excess smoke Fwiw
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Oonrahnjay
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« Reply #10 on: November 08, 2013, 07:37:49 AM »

  That is exactly the problem Doyle has Bruce when he gives it throttle it goes to 100% throttle then comes back down    

     I didn't describe my situation very well.  When I give it like 10% of pedal movement, the fuel injector system gives 30% of engine power; when I give it 20% of pedal movement, the fuel injector system gives 60% of engine power; when I give it 30% of pedal, the engine is at full fuel injector control movement and power.  So, for that first 1/3 of pedal movement, it's entirely controllable and works OK but all it takes is a little bump with your foot to "blip" the power.  The throttle control is smooth and linear (as it should be) and it doesn't go anywhere I don't want it to -- my issue is that it all happens in the first 30% of pedal movement and that makes it feel "touchy" to my foot.

    As I mentioned in my earlier post, I'm pretty sure that I have the angle and leverage wrong on the linkage from the output rod on the engine cylinder to the fuel injector control on the engine and that's probably the biggest part of my problem.  But I'm also running full pressure and that should be reduced.  I'll reduce the pressure first and test it and post the results. 

    Thanks for the input and advice.   BH   
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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

(New Email -- brucebearnc@ (theGoogle gmail place) .com)
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