A nice rendition of a would be American Garratt. What you referred to as a shield for the steam pipes is in reality the deep ash pan of the Garratt. Garratts would have wider and deeper fireboxes than possible on rigid locomotives as there were no wheels under the firebox. For this reason it would have been more prototypical to construct a boiler with a very large diameter, and a firebox with a vertical front plate and reaching deep. Because of the width of the firebox, often almost the loading gauge, steam pipes could only be run underneath the ash pan, there is a cutout along the centerline to accommodate these pipes. The place of the air pump high on the running board at the boiler side is prototypical for a Garratt, you could have left the power reverser on the other side as well, many Garratts had them in this same spot with actuator bars going to the front and aft units. These were articulated at the point where the loco was articulated. The Pennsy style bath tub water tank on the front unit is very elegant looking, and forms a unique feature. And indeed, for American railroading practice having the rear bunker almost completely for coal and have an auxiliary water tank like on these South African GMAM locomotives could be the best option, the water tanker could be a centipede tender but with water space only. To counter the problem of reduced adhesion with low stores an axle configuration like 4-8-0+0-8-4 or 2-10-0+0-10-2 would be a logical choice, as relatively more boiler cradle weight is on the drivers then, and less weight change on these driver by percentage when coal and water is used. But the addition of trailing trucks on the inside was very convenient for you to motorize the model, I assume the original drives were in the wrong place.
Well done project, have always contemplated an American Beyer Garrett and yours was well done. Suggestions: smoke deflectors on either side of the smokestack would balance the narrow boiler, if you get tired of the shark nose you could consider the streamlined water tank of the Rhodesian Garretts. Hope I dont come off as supercriical as I am jealous about your skill, enjoy your beautiful handiwork.
I can see the fun in this project. Perhaps just to add more PRR caracter, a Shark Nose like T-1 or BP 20 A shark nose diesel would be even better. But in any event, you nail in most details. Also this video gave me inspiration to tackle a Garratt project that I’ve been thinking about tackling for a long time a SPR 4-6-2 2-6-4 Garratt, interesting, I went almost the same route for the driving engines as you did it. I may adapt the same idea of using NWSL Spuds.
Alco had the North American license for Garratts. Another reason why Garratts were unnecessary in North America is axle loadings. Garratts are known to be gentle on thin track. And, except for the Australian lines built to AAR standards, North American railroads have the strongest rail of all.
Check you mallett & garrett comparison picture, see how the front boiler section rest, with the mallett setup, ideal to give a garrett a longer boiler, thus more power. Which could give you a 4-6-6-4-----4-6-4, with the boiler resting on the 6-4-----4 section. Then check the Flying Scotsman it's walk true tender out as well, for a nice looking back-end, if you are going to put to the track, something that has never existed, why not going almost all the way? All the way would be adding the condensator tender ability to it as well. Still, very nice work and good looking as well. Keep up the nice & good hobby work. 👍
To be more Prototypical, in order to supply sufficient steam to the two independant engine units; the Boilers of Garret locos were of large diameter than a single engine loco boiler. The lenght of the Boiler could be then shorter ( suitable for tight curves on NG systems. As to the loss of adhesion as coal/ water are used up, in many countries ( and now re-enactment Runs, a water tanker with a syphon system keeps the adhesivo wright reasonably estable for longer; for a fuel oil fired versión an extra oil tankcar would lenghten the rnge as well. My suggestions would be a IHB 0-8-0 boiler, between two 4-8-2 Frames, and Boxlike forward and dear tenders Same applies for a Super ( Mallet-Garret) To be believable, a large Boiler is essential DocAV from Garret country 3'6" Queensland Australia.
looks terrific, but it is obvious that the boiler was not made for a Garratt. You don't need that sloped back and flat firebox that was made for decapod wheels underneath, a garratt boiler always has the optimal stubby shape with straight firebox walls
The double Baltic was used in Sudan, Rhodesia and Mozambique, but all were 3'6" gauge. I think the USA didn't use Garratts as they regarded them as tank locomotives, with too short range for running on mainline. Mind you, a variant with 100 % coal on the rear engine and an auxiliary water tender might have been OK. But weight change (and therefore tractive effort change) was also regarded as a disincentive (that because all American railroads were parsimonious on loco provision in the interest of ekeing out the most train for the least money.
Crazy great! Mostly the video was straight forward. I was wondering, however, where you got some of the small, more decorative pieces such as piping, railing, etc. The cast parts on the front end, for example. Did you cast them or acquire them. I've never attempted something like this but it would be an interesting endeavor.
I keep a large assortment of old CalScale and Kemtron detail parts. Sometimes I'll fashion small parts with a lathe. Never tried to make my own castings ... yet :-)
Those triplex locomotives most likely did not have enough steam power, by having a too small boiler, their front section is afteral a standard mallet setup, a garret most often has a similar boiler size as a mallet. A mallet triplex probably can only thus have enough steam pressure and thus power, if it's also a garrett, which would let you get away with a boiler that's 1/3th longer, with all that that means. It's a bit hard to put a forwards motion strenght of say 18, on the tracks, when you can only produce enough for 12, you just can't get it up to speed, as easily as should be possible, I bet.
Because the cg swings to the inside instead of outside on curves, they're much more stable. Not sure about the added costs of the apparent higher complexity.
Generally Garratts were technically competent, but not massively complex. The tricky bit is the steam connections, but that was nailed on the Semi-Mallets, so wouldn't be a huge issue for the likes of some of the US builders. I'd never considered John's viewpoint of Beyer-Peacock's defence of their patent...
It's nice but, shouldnt the rear drivers of the 2 engine units be under the boiler section? So realistically the weight of the boiler would be on them, instead of the coal and water which will vary overtime and may cause wheelslip?
Some Garratts with single axle pony trucks did have their drivers more under the extended carriage holding the boiler. This was not usually the case with 4-wheel bogie trucks. You are absolutely right that loss of traction was a concern for Garratts as fuel was consumed.
Absolutely gorgeous model! I must ask, does the rear tender have a water tank? If so, why? Wouldn’t the front water tank hold enough? Thank you, and keep up the fabulous work!
