Power comparisons.

[pre65]

Is the class 37 diesel the modern equivilent of the "black 5", or other locos of that 5 MT classification ?

[swisstrains]

I've often tried comparing steam and modern traction myself but never come to any real conclusions. If you look at "Tractive Effort" figures even the smaller diesels and electrics appear to be much higher than most steam locos but I don't think it can be as straightforward as that.
Maybe Alan (Locojoe) can give us his impression of how the prototype Deltic and the English Electric Type 4's compared with the ex-LNER Pacifics?

[Triplex]

If you look at "Tractive Effort" figures even the smaller diesels and electrics appear to be much higher than most steam locos but I don't think it can be as straightforward as that.

Speaking from a North American perspective, but I expect it's the same everywhere...
Diesels tend to have higher tractive effort than steam locomotives that could produce the same horsepower at speed. It's not hard to see why: diesels generally have all axles driven, and their wheels are smaller (thus more torque). Thus, their operating characteristics are different. For example, replacing a steam locomotive on a fast train with diesels would often mean that it no longer needed a pusher on a grade.

[swisstrains]

Originally Posted by Triplex

................ It's not hard to see why.................

It was for me

[John H-T]

There was an article in, I think, a recent copy of the Railway Magazine which tried to unravel all this. Sadly I haven't read it, just skimmed through. Tractive Effort is not always a reliable guide as it is a mathmatical formula. In theory, comparing TE, a GWR King should be as powerful as a LMS Duchess. In real life this just isn't the case. Draw Bar Horse Power is more reliable and is measured in real life testing. To the best of my knowledge the highest figure ever recorded was for a Duchess. I am writing all this off the top of my head as I do not have the time to do the reseach to back it all up.

However I am sure that I will be corrected if this is all total rubish!

Best wishes,

John H-T.

[locojoe]

When working expresses from Kings Cross a pacific had to be worked hard on the rising gradient to Potters Bar. From memory of working on the Prototype Deltic and various Pacifics, Prototype Deltic was more powerful in my opinion, I've never been very good at the technical side of locomotives mostly I shovelled coal.

[John H-T]

Originally Posted by locojoe

When working expresses from Kings Cross a pacific had to be worked hard on the rising gradient to Potters Bar. From memory of working on the Prototype Deltic and various Pacifics, Prototype Deltic was more powerful in my opinion, I've never been very good at the technical side of locomotives mostly I shovelled coal.

Thanks locojoe. I am sure you are in a much better position than most of us to make these judgements.

There is an article in the LMS Journal no.25 on Stanier's proposed 4-6-4 which would have pushed steam loco design to the limit of the British loading gauge. It would have needed a mechanical stoker and had a boiler pushed to 300psi.

It is another article I have not yet had the chance to read but have skimmed it. The theory is put forward that it would have been the equal of a Deltic so quite an impressive machine. Sadly the war stopped progress and steam design for UK railways was never pushed any further than the Duchess, which must therefore remain the ultimate!

Best wishes,

John H-T.

[ccmmick]

I had an argument with an old guy years ago about steam and deisel a modern deisel would pull a lot more loaded clay wagons over the graidients in cornwall than steam would ever do in the end we had to agree to disagree.
Plus in steam days there was always a banker at Plymouth for all up trains over Hemerdon incline as elsewhere in the country, now a class 66 will pull a thousand ton train up the bank.
ccmmick.

[ROUGH TOR]

The only example that springs to mind is that I remember reading that a Class 33 "Crompton" fell inbetween a "King Arthur" and a "West Country" in power terms.
It does get muddled though, as an "Arthur" is more powerful than a "Schools" Class on paper, but apparently not so in practice.
Not sure that helped much, sorry.

[John H-T]

Originally Posted by ROUGH TOR

The only example that springs to mind is that I remember reading that a Class 33 "Crompton" fell inbetween a "King Arthur" and a "West Country" in power terms.
It does get muddled though, as an "Arthur" is more powerful than a "Schools" Class on paper, but apparently not so in practice.
Not sure that helped much, sorry.

Interesting. Power is one thing but making use of it is another!

Here is a quote from an Article in the Glasgow and South Western Railway Association Journal celebrating the work of Scottish Steam Locomotive Engineers, written by Derek Cross:

"In the first 2 years of the 1950's I travelled on this train (2.34pm Ashford to Charing Cross, normally hauled by an "Arthur") many times and with an Arthur it was never late whatever Tonbridge or Orpington might throw in its path. The occasional Battle of Britain had a sporting chance but not an infallible record. The rare Schools surprisingly could not do it, it was those nasty wet tunnels on either side of Sevenoaks that beat them."

I throw it into the ring for interest!

Cross also commented: " Second best is a nasty word these days, but second best to a black five is no mean achievement and the King Arturs were splendid machines." especially as Cross considered the Black Fives to be the best of all British Designs.

Best wishes,

John H-T.