Discussion in 'Steam Traction' started by aron33, Aug 15, 2017.
I prefer their predecessors with larger driving wheels.
One thing we have realised about Mr. Urie - he knew the value of a £1. He would no more have thrown good money at one of the 'Butterflies' than flown to the Moon. Simple and solid are the hallmarks of his oeuvre. The first H15s (thrown into the deep end of the 1st WW) ran stonking great mileages before their first Generals - only 2 were less than 170, 000 miles (and one of those was taken in to be superheated). I bet they were pretty rough by then, mind.
Glad to see so much progress made in the midst of a global pandemic.
If someone announced a project to build a Raven design from the NER, I would pass out right now.
A B16/3 and a dynamometer car to compare it to the rest?
By the way: Why was wheelbase changed going from B16/1 to /3?
A B16 was definitely a preservation "miss" and shows how Woodhams influenced today's preslines.
And frame extensions to fit the latter 2s valve gear!
But can you imagine the factions/disputes and petty bickering over all 3 subtypes.
The Raven originalists, the Gresley perfectionists, and the Thompson apologists!
Sounds like fun!
So basically the Thompson thread in engine form?
Only one solution build all three versions.
Yes and after evaluation the two least desirable will be rebuilt as Three and two cylinder compound Chapelon challengers.
On the subject of North Eastern engines and compounding, the Worsdell C8 would appeal to me.
Very nice that C8 but why did designer go to four cylinders after having proved that three cylinder compounds worked well?
I quite like the look of the HR River Class.
just a guess, but I'd reckon that using a 90/180 degree layout, which isn't the best, but most common arrangement four cylinders the design can get by using 2 sets of valve gear, the combination of inside/outside admission even does away with the need for 'Rockers' , whereas 3 cylinders would require either 3 sets of valve gear or a form of 'Gresley Gear' which would probably have involved royalties to the GNR, so contrary to expectations a four can be both simpler and cheaper to produce than a three, but at the expense of reciprocating balance, I would imagine that with unified drive the horizontal couple in the axle box/hornblock area of the crank axle would have been considerable.
Doesn't a 3 cylinder Smith compound have the outside cylinder cranks at 90 degrees? If So you couldn't use Gresley gear or any similar conjugation anyway, because that requires 120 degree spacing of the cranks.
Edit: corrected a mistake made by hasty typing.
That is correct. Some 3-cylinder compounds in Switzerland and Wurttemberg did use the alternative arrangement of 120 degree crank spacing, which would have produced a more even draw-bar pull but an odd-sounding 6/8 exhaust. As far as I know, no-one ever tried a conjugated valve gear arrangement on a compound.
The Midland/LMS 4-4-0 was by some margin the world's numerous class of 3-cylinder compound. On the global scene, the type was a rarity.
You've half said it. As you couldn't use Gresley gear, a third set of full valve gear is needed, which is a full set of valve gear more than a four with 90/180 can get by with. particularly using both inside and outside admission valves, as in this case.
Yes I do too. They also had two quite modern looking 4-4-0s built at about the same time
I expect Harold Holcroft could have solved that problem. The so called Gresley conjugated gear was actually designed by him. He also designed an arrangement which could operate 4 valves for a 4 cylinder engine with cranks set at 135 degrees (8 beats per revolution) from 2 sets of valve gear.
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Conjugated gear could be designed for the 90 degree arrangement, it's just that the lengths of the levers would need to be different.
The thing that has puzzled me about four cylinder compounds, if you assume early release from the HP cylinders, the HP exhaust valves would not be open at the same time as the LP inlet valves.
I am thinking that the Lord Nelson 45 degree arrangement would work better than the 180 degree arrangement (on a four cylinder compound) in this respect, but I don't know if anyone ever tried.
Never quite got it myself either, always assumed that the HP exhausted to some intermediate steam chest but this would mean that the work done by the HP engine would be effectively at the HP minus the LP pressure. and that the exhaust post the LP engine would be quite weak and effect draughting. But then I am a bear of little brain....
It is windy and raining,life is short and steam locomotives were some of the most interesting things in my life.
Allow me to play that there were 10 B16 and no Halls preserved
NER T3 and S3 were constructed to use same cylinders and boilers and did that very well.
The outside 18 inch cylinders were 6 feet 8 apart being outside the coupling rod.
I have Ken Hooles lovely NER book and the drawing of the S3 clearly shows this.
This is an all time low figure and has been difficult to achieve just as Schmidts three-cylinder compound 4-4-0 with conrods inside coupling rods that achieved 6 feet two inches.
There is no drawing of the NER Pacific but let us asume that the monoblock cyliners were a sligth modification of the aforementioned T3/S3.
At any rate some lines on NER could accept 19 inch cylinders 6 feet eigth apart.If two 25 inch cylinders had been used on S3 or Pacific and attacking inside first coupling rod they would have been usefull somewhere on NER.
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