For those of you who are interested in Welch narrow gauge, it looks like Roundhouse is going to start making a single fairlie soon. You can see the cad drawings of the model at www.roundhouse-eng.com Looks pretty neat.
You got me excited, I was hoping that it would be a double Fairlie. Since they use the same power bogies, perhaps a double will follow sometime in the not too distant future. I'm not sure how you would go about making a gas fired version though.
Mornin, Roger. Great confunglement here in the tac hutch about your post. What to do mean about 'making a gas-fired version'? The Roundhouse Single Fairlie is gas-fired and 'bendy' so why shouldn't a double Fairlie be the same? After all, it's only two loco chassis joined by a cab, after all.
Single Fairlie is priced around £1750 here in UK, BTW./DesktopModules/NTForums/themes/mls/emoticons/whistling.gif
Well, in answer to your question, I just called up Roundhouse and spoke to Chris herself. She informs me that Roundhouse has no plans at present to produce a Double Fairlie.
Your grandchildrens' inheritance is safe.
However, if you are interested in the Single Fairlie, my advice to you and to anybody else on your side of the Great Water who is interested is to get your name on the rapidly expanding list as soon as possible.
The Ffestiniog and its little locos has a VERY large following over here in its homeland, and i wouldn't like to think you missed the boat.... /DesktopModules/NTForums/themes/mls/emoticons/whistling.gif
So correct me if I'm wrong. A double Fairlie is two working boilers but steaming independent from each other joined by one frame. Pretty much what Tac said two loco's joined at the cab.
Neat concept, one engine but the tractive effort of two.
Bruce, the double Fairlie is one boiler with two fireboxes, there is only one water space, I built 4 Double Fairlies in the 90's with a burner for each end, full Stephensons valve gear, the main problem was getting the two sets of valve gear in unison.
I was one of the crew that built the replica single fairlie on the Festiniog railway, although we termed it a "rebuild" as we used some of the original parts from the one which was scrapped.
David Bailey www.djbengineering.co.uk
David, thanks for the correction. So the boiler goes straight through the cab and the two fireboxes back to back or almost. I guess you would need room to shove coal in her. If the boiler has two fireboxes I guess it would have two sets of flues and two blowers right, but one throttle.
Inquiring minds want to learn about other loco's we don't get to see on this side of the pond.
Posted By Bruce on 04/08/2008 8:20 AM
So correct me if I'm wrong. A double Fairlie is two working boilers but steaming independent from each other joined by one frame. Pretty much what Tac said two loco's joined at the cab. Bruce
nossir, it has only one large boiler, but with two fireboxes - as seen in the drawing below, based on 'Merddin Emrys'. This double arrangement is fed by fireholes at the sides, to enable some rather gymnastic feeding to take place, if it were coal-fired, but I bleeve that it is actually oil-fired, which makes the feeding somewhat easier...
See - http://www.frheritage.org.uk/wiki/Fairlie's_Patent
tac the Griper www.ovgrs.org
Tac, Thanks for making the call. You broke my heart but spared my wallet.
David, If Roundhouse was ever to pursue the idea of a double, it looks like they have a built in answer for the timing problem. From the images on their website it appears there is a servo built into the back of the power bogie. That would making timing two bogies together a snap.
Bruce, While they are both long gone, the D&RGW and the Lehigh Valley both once had double Fairlie's.
Tac (again), Due to the cost of oil the Ffestiniog has converted a couple of their doubles to coal firing again. They probably don't have long handles shovels.
Roger, it is easy with a single Fairlie, but getting two lots of valve gear to syncronise with only one reversing lever with all the flexible joints required, and with one unit in reverse and one in forward gear is not easy.
The full size engines have two regulators, so it is possible to run on one end only, usefull when shunting stock etc.
David Bailey www.djbengineering.co.uk
I should not have used the term 'timing' in my last post, I did mean synchronizing the valve settings. I understand that trying to do that mechanically in these small engines must be been maddening.
If you look carefully at the illustration on the Roundhouse website it looks like they have incorporated an r/c servo into the rear end of the power bogie. With programmable r/c transmitters I would think it would be quite simple to synchronize the two power bogies electronically rather than mechanically. There would be no fiddly little bits to coordinate, just raise or lower the throws of the servos and viola, syncronized valve settings. I may well be oversimplifying the problem, but it seems like a good solution.
If you wanted to build a double ended Fairlie that actually had two independent boilers, you could model one of the Junin Railway's 30 inch gauge 0-6+6-0T Fairlies. Two of them were built in 1905 for the Junin Railway, a nitrate line in northern Chile. They were 40 feet 4 inches overall, and each outside frame power bogie had a six foot wheelbase. For more details and plans, see Donald Binns "The Nitrate Railways" from Trackside Publications. I agree with Roger that independent r/c servos in each bogie should solve the problems of mechanical connections. Of course, if you were mechanically inclined, you might be able to replicate the system the Junin engines used to connect the valve gear with the cab: they had vertical rods on each side of the engine that were connected to a horizontal shaft atop the boiler, a system very similar to the one used on the DSP&P 3 foot gauge Mason Bogies.
If you modelled one in 1/22.5 scale, the Roundhouse 0-6-0 power bogie and boiler should be about the right size, although the smokebox would need to be slightly extended.
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