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Discussion Starter · #21 ·
Ray, don't take offense at Dwight - he's only trying to help.  (Everyone has problems with the stupid photo posting at first.)  /DesktopModules/NTForums/themes/mls/emoticons/crazy.gif

We need a furnace guy to keep us straight!  And we'd love to see your photos - did you get the email?
 

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Discussion Starter · #23 ·
Shame we lost Ray - his ideas were good and I was hoping he'd add some more details...

Anyway, I finally got a chance this weekend to test the new stack - and it works!



As Ray discovered, the smokebox needs air flow. There was a thread by emartin187 (http://www.mylargescale.com/Community/Forums/tabid/56/forumid/11/tpage/1/view/topic/postid/6760/Default.aspx#25175) about drilling out the stack, and my new 9/16th ID version worked a treat. Didn't have to relight the fire once until I was out of gas.

But of course, being a Ruby, that wasn't the end of my problems. The new r/c servos seemed to work, but the loco wouldn't run forwards. I disconnected everything, and found that backwards running was perfect, and forwards was painful. Didn't have this problem before, so it may be that loosening the johnson bar pivot to attach the servo has brought out the deadly inside/outside-admission problem.
Unlike my C-16 which works every time I take it out.
 

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If the mounting plate of the Johnson bar was loosened, it perhaps shifted the center position of the valve piston, letting more steam flow forward or reverse. The mounting plate is used to "centre" the main steam valve - you'll find that forward or reverse performance is affected by the position of the plate. Too far one way or the other and the centre bar position won't stop motion (either way), and there's enough latitude to affect the amount of steam admitted by the valve porting for either forward or reverse. (Did that make sense?)
 

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Discussion Starter · #26 ·
If the mounting plate of the Johnson bar was loosened

Paul,

The annoying thing is that I never touched the mounting of the Johnson bar. I did weaken the spring that holds the J-bar to the frame to amke life easier for the servo, and I removed the bolt that fits in the indents - but the valve timing should have been the same. As Dwight says, it's probably just a matter of getting it all back to square one.
Probably time I did the inside-admission thing as well.

What's disheartening is that, as I don't have a test track, I have to spend all my visits to friends tracks fiddling with these problems, instead of enjoying the run. Well, that's a Ruby for you...
 

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Posted By Pete Thornton on 04/23/2008 6:37 AM
If the mounting plate of the Johnson bar was loosened

Paul,
The annoying thing is that I never touched the mounting of the Johnson bar. I did weaken the spring that holds the J-bar to the frame to amke life easier for the servo, and I removed the bolt that fits in the indents - but the valve timing should have been the same. As Dwight says, it's probably just a matter of getting it all back to square one.
Probably time I did the inside-admission thing as well.
What's disheartening is that, as I don't have a test track, I have to spend all my visits to friends tracks fiddling with these problems, instead of enjoying the run. Well, that's a Ruby for you...

What I'm trying to say, is the mounting of the j-bar assembly is part of the mix for balancing the forward/backward balance of the Ruby motion - its the reason the plate has slotted screws (and Accucraft mentions this in their instructions). Its possible for the plate to shift in handling. If you haven't messed with the timing of any of the pistons, then movement of the j-bar mount is suspect. Regardless whether you change timing or not, centering of the j-bar linkage is important to the relative performance backward to forward.
You don't need a test track- make up a simple stand that supports the Ruby on its front and rear pilot frames, so that the wheels are clear and run away- you can make the adjustments easily that way - if you have a source of air, its even easier to set it up.
There are four areas to set-up in the timing of the Ruby:
1) Main piston in the steam chest under the boiler
2) Relationship of the j-bar/linkage to the main piston
3) Right and left side cylinder pistons
4) Setup of the eccentric
It just clicked that you have a servo on the j-bar...the set-up of the servo driving the j-bar must exactly duplicate the relationship that existed without the servo. Do this first before adjusting timing, if you haven't fiddled with the timing. There are two issues with the servo position - the position of the linkage arm at servo neutral must coincide with the neutral position of the linkage itself, relative to the piston in the steam chest. Secondly the motion either side of neutral should be the same, ie, if you are using end point sets on your transmitter, make sure the end point sets are symmetrical either side of neutral, or the motion won't be symmetrical either side.
Generally, Ruby benefits from having the j-bar's [linkage] neutral set so that it slightly favours forward motion in outside admission (ie runs a bit better forward than in reverse). Switching to inside admission doesn't change this, but does reverse the linkage adjustments necessary to achieve it. The range of neutral is a bit fiddly - too much either way and the steam chest will still pass a bit of steam to the cylinders.
 

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Discussion Starter · #28 ·
Paul,

Thanks for the helpful comments. As you say, maybe the J-bar mounting shifted; maybe the servo dragged it!

The test track issue is another source of frustration. I've tried running the loco on my patio on blocks, but it doesn't exhibit the same characteristics as it does when placed on the track and hauling its own weight! Maybe a more drastic problem like this will show up, so it is on my list of things to try when I get a moment.

I'm just irritated because my C-16 never had the slightest problem, even after I added the r/c gear.
 

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Well, I agree, on blocks it doesn't load it the same. At least it will get you into a running ballpark. A point to recognize is that now that you have changed the exhaust porting of the engine, its entire power/exhaust cycle will be changed, or more importantly, not optimum for the change in back pressure. Make sure the j-bar linkage is set-up correctly and neutral (relative to the action of the stream chest, in the center position) before you begin to play with timing. If a neutral position isn't... and the wire controlling the link hasn't changed shape, then adjust the steam chest piston to bring the chest and j-bar back to neutral (small adjustments can be accommodated by the baseplate/servo link).

I have two Rubies that are only a couple dozen apart in serial number. The steam chest/j-bar linkage is different in each, and one runs better in outside admission and the other, seemingly, in inside admission. Go figure. I haven't R/C'd them. What I do want to do is run them together in a consist and see if together they'll hunker down and haul some serious freight. So many trains, so little time! The basic Rubies seem to be fairly solid runners - its seems the artsy-f*rtsy ones have "issues"... :)
 

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hi guys, i have just acquired a ruby to run round my narrow garden as i scratchbuild gauge 1 locos that need larger radius curves and i have all the things discussed on your posts happening to it. first thing is, in the info supplied, there is a fix for the valve timing to make the loco run better forwards, and that is to loosen the eccentrics and turn the wheels 180 degrees and retighten. you then run forwards with the valve lever in back position and reverse with it forwards. the valves are then set for "inside" admission which makes for better running. it does work fine on my ruby. other thing is the fire does burble and go out when the smokebox door is shut, so will experiment with larger opening on the chimney (stack). i intend to do the "rubybash" and convert to a british rail B4 loco to fit in with my others when i have finished my current loco, an LMS duchess. have just put some new buffer beams on ready for a run at the next get together. will post a pic or 2 as it develops. gas is new to me being a meths firing enthusiast. kind regards, martin....
 

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and i forgot to mention, when i got the half built loco, the left rear port was blocked and i feared it may need a new cylinder or valve block. i loosened the valveblock screws and bent it up slightly to check steam passages, and luckily caught sight of the fact that the gasket was back to front, just as was mentioned in an earlier thread. easy to put right but tricky to diagnose for a beginner i would think. not sure if it came from the factory like that or whether the previous owner had built it that way. oh, and the wheel bearing bushes were too tight in the frames, causing binding. they need a little movement i think. runs well on the test bench now. bfn... martin
 

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just to say that a bigger chimney sorts out the burner going out when smokebox door is shut problem. i used some 1/2" plumbers pipe and a brass flange and it works fine. sorted. will put up a pic if anyone would like to see. thanx, mart...
 

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just to say that a bigger chimney sorts out the burner going out when smokebox door is shut problem. i used some 1/2" plumbers pipe and a brass flange and it works fine. sorted. will put up a pic if anyone would like to see. thanx, mart...

I'd like to see the picture of your larger stack!:rolleyes:
 
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