[34C]

QUOTE (steamrailuk @ 18 Aug 2008, 16:35) <{POST_SNAPBACK}>Is that the reason why american loco's have very large coupling rods compared to british loco's?
Yup. On the final US maximum power designs the power that had to be transmitted, is at about a 3:1 ratio: 6,000hp as compared to 2,000hp in the UK.

 

[steamrailuk]

QUOTE (34C @ 18 Aug 2008, 20:49) <{POST_SNAPBACK}>Yup. On the final US maximum power designs the power that had to be transmitted, is at about a 3:1 ratio: 6,000hp as compared to 2,000hp in the UK.
thanks for that, always wondered about that on american locos. What do think about my suggestion for a combined Tornado design with the advances made in Duke of Gloucester as a development platform for a modern steam loco

 

[34C]

QUOTE (steamrailuk @ 18 Aug 2008, 20:59) <{POST_SNAPBACK}>thanks for that, always wondered about that on american locos. What do think about my suggestion for a combined Tornado design with the advances made in Duke of Gloucester as a development platform for a modern steam loco
A step in the right direction. Now all you need is years of academic and practical engineering experience, a dozen or more people with similar qualifications, and a large wodge of the folding stuff. An outline concept is one thing, developing this to a credible project proposal a serious business, the design process a severe test of ability and stamina: and then you have to build the thing...

If you have that kind of ability and energy, while building an example of an obsolete form of railway traction would be fun, I cannot help but feel that working on power generation might actually be more useful for society.

Oh yes, something I didn't mention about the rods on US locos, the late designs had roller bearings on the crankpins, which need much larger housings compared to the plain bearings used in UK steam practise; that also pushed up the size of the rod cross sections.

 

[steamrailuk]

QUOTE (34C @ 18 Aug 2008, 22:56) <{POST_SNAPBACK}>If you have that kind of ability and energy, while building an example of an obsolete form of railway traction would be fun, I cannot help but feel that working on power generation might actually be more useful for society.

Unfotunatly I dont have that kind of expertise, it was just a suggestion as you said it would be a really big challenge to build an advanced steam loco from scratch rather than develope and existing design.

 

[John-Pro]

QUOTE (steamrailuk @ 11 Aug 2008, 18:02) <{POST_SNAPBACK}>Hey everyone, I came across a loco project a while ago that you would be very interested in. The project is called the 5AT and will be the most advanced, efficent and possibly even the fastest steam loco in the world if given the chance. Loosely based on the BR 5MT 4-6-0, this loco will incorperate many of the advances in steam technology from locos such as SLM class 52 or the The Red Devil

Heres the link to the 5AT project to find out more http://www.5at.co.uk/

The thing about a project is that it is somebodys dream, it will defy logic in its concept, it will defy argument as to what is best, it will be as its creators masterpiece, and when we look around we must be thankful that they stuck with their dream.

John-Pro

 

[steamrailuk]

34C I was wondering since you have a better knowledge of american locos than me, I was wondering if you could clear something up for me.

I was looking on the net and I came across a video of the Chesapeake & Ohio 614. In this video and on its website co614 it claims that this loco can produce 5000 horsepower and to my anstonishment it can reach 120mph. Can a loco of this size be capable of running almost as fast as Mallard?

I know locos that have small diameter wheels are capable of high speeds as I've heard stories that Evening Star could haul expresses up to 90mph, but is it possible to reach 120 without causing serious damage to either loco or track?

 

[34C]

QUOTE (steamrailuk @ 25 Aug 2008, 17:48) <{POST_SNAPBACK}>.. it claims that this loco can produce 5000 horsepower and to my astonishment it can reach 120mph. Can a loco of this size be capable of running almost as fast as Mallard?

I know locos that have small diameter wheels are capable of high speeds as I've heard stories that Evening Star could haul expresses up to 90mph, but is it possible to reach 120 without causing serious damage to either loco or track?
The power output is nothing extraordinary for the final express 'superpower', and should be adequate for the speed claim. For comparison the NY Central's final brute the 4-8-4 'Niagara' was good for 6,000hp. The Chessie laid some of the heaviest rail used in the steam era, capable of accepting the 42 ton axle load of their H8 2-6-6-6 simple mallets (a freight machine with an output over 7,000hp), which may well have enabled the track to stand the pounding of the J3 4-8-4. The 72"wheels are a bit on the small side for the ultimate in speed; the Hiawathas had 84" and quite definitely ran over the 100mph mark in daily service, simply to make schedule. These likely were the fastest ever steam locos in regular service. Somehow it never occurred to anyone to formally time one at full chat...

Quite how well the loco stands up to the battering long term is just one reason why I have my doubts about the 5AT project. The US experience in the final 'superpower' locos weighing around 200 tons was that a cast steel frame with integral cylinders was the way to go. Their experience showed that built up constructions were worked to failure by the piston thrusts of around 80 to 90 tons, alternating each side, bending the frame. Trying to accomodate the necessary 50 ton or thereabouts thrusts within the 90 ton all up 'envelope' of the 5AT is going to be challenging in the extreme. Compare to the UK experience with locos that were called upon regularly to put out approaching 2,000hp: the Princess Coronations suffered from loose cylinders throughout their career, the A4's were noted for deforming their frames: and these were 4 and 3 cylinder designs, not 2 cylinder. The US designs have roller bearings on the axles and the coupling rod pins; more weight, but necessary to stand up to the hammering. The rod cross sections have to be heavier to house the bearings, more weight required for rotational balance...

The final developements in US steam power make fascinating reading, and much of it is now on the web. 'Why didn't the PRR duplexii succeed?' is always a good one!

 

[Stanier6256]

Speaking as one who was trained as a steam loco designer by the late NBL I have to say, in spite of any enthusiasm we all have for our beloved engines, that there is no chance of there ever being a resurgence of steam unless the cataclysm of a nuclear war was to occur. The Rankine efficiency of a steam loco cannot exceed 17% without breaking the laws of thermodynamics. The best locos ever built never came anywhere near that number - 3-4% was more like it when standby losses were taken into account. As far as rail traction is concerned the correct solution is to use electricity. A modern fuel fired power station has a Rankine efficiency of around 30% and most units get to around 28%. Nuclear power stations are ultimately steam driven at the generator level but fuel efficiency is somewhat nugatory in this case.

The steam loco needed (and got in its heyday) abundant cheap fuel and cheap labour neither of which are now available.