Sir Nigel Gresley - The L.N.E.R.’s First C.M.E.

OK, let's be specific. What is incorrect about the entry above?

 

As I will explain in my forthcoming Gresley book, it’s really not that simple and there is ample evidence to suggest that there are specific circumstances in which the conjugated gear had its advantages, on certain types of loco, compared to others.

 

I do have the feeling that if the LNER had designed a better big end then the conjugated gear wouldn't have had nearly such a shaky reputation.

 

I think you’re right. Post nationalisation, the redesigned big end pretty much cured the problem by all accounts.

 

Thanks to Mr Cook. From Swindon!

 

It's a little sidelight on design influences as we were talking about above... According to Cook, Collett got the idea of introducing felt pad lubrication for connecting rods from machine tools in Swindon Works.

 

It's a bit eclectic in what it puts in and leaves out e.g.
- Holcroft's paper to the ILocoE of November 1918 on Three Cylinder Locomotives tackles the geometry of conjugated gear.
- the D49s also had the conjugating lever to the rear of the cylinders
- the inside valve also tended to overrun, hence the maximum cut-off was restricted to limit valve travel (65/66% for the V2)
- the steam distribution in the middle cylinder was poor - see e.g. the BR P&E test bulletin for the V2 and the asymmetric indicator diagrams therein (albeit this was not an issue that was easily rectified nor arguably did it make much difference to the performance)
- the UP 9000 "double Walschaerts" modification is not explained. Possibly the same as for the Thai Baldwin Pacifics?
- the Thai Baldwin Pacifics used Gresley gear on the first batch (conjugating lever to the rear of the cylinders) but it was abandoned for the next batch (which used two return cranks on the LHS), which suggests that they were less than impressed with the gear (this Thai example would be a useful addition to the non-UK examples).

 

It was one of several changes that were made post war to the overhaul and maintenance of Gresley Pacifics and cannot be seen in isolation without reference to the - in my view - infinitely more important setting up of the frames and the increased tolerances with which the Pacifics and other engines with conjugated valve gear were rebuilt.

 

Gresley had a very strong incentive to use his own valve gear. It was his patent and no doubt he was paid handsomely each time it was used.
"And the big ends gone," a famous phrase. When working well maintained, Gresleys big end was a spectacular stumbling upon a type of super compounding of increased middle cylinder power, inexplicably providing a greater effort than the theory.
Hence, the world famous Gresley beat

 

Well, the very first sentence is I'd say somewhat muddled (being kind):

"The Gresley conjugated valve gear is a valve gear for steam locomotives designed by Sir Nigel Gresley, chief mechanical engineer of the LNER, assisted by Harold Holcroft."

That strongly implies that Holcroft was Gresley's assistant, which is not true - he worked for the SECR (and then the SR), not the GNR / LNER. A better understanding would be that Holcroft presented a paper in which he outlined the geometric solution to conjugated valve gear; subsequently Gresley and Maunsell both built (separate) implementations based on that geometric understanding.

Tom

 

Would Gresley have been paid for the patent on his employer's line?

Holcroft certainly assisted Gresley (to say the least). I'm quite sure you know all this, but for others...

The time scale (from Holcroft's book) seems to be that Joy first invented a conjugated gear for marine triple expansion compounds in the 19thC. Holcroft independently conceived his own design and patented it in 1909 while working for the GWR. Gresley patented his variation in 1915, and built a locomotive which was described and illustrated in "The Engineer" in 1918. Holcroft suggested a major improvement to Gresley's original concept in a letter to "the Engineer", met with Gresley for a detailed discussion, and was informally offered a job in 1919.

Holcroft's book implies that Gresley was well aware of Holcroft's original patent and found a loop hole in it - otherwise it would have been Holcroft doing well on the patent - and he didn't work for the LNER. Its unclear to me whether Gresley had the idea independently and revised it to work round Holcroft's patent, or whether he had seen Holcroft's patent and developed his ideas from it.

There's an interesting What If there - if Maunsell had released Holcroft to go to Doncaster isn't it likely that long travel valve gear and >200psi boiler pressure would have made their way onto LNER locomotives much earlier? And if that had been the case would the A1 have been much better matched with the Castle in 1925?

 

The statement is not incorrect.

From Holcroft's entry in Wikipedia: "Somewhat later, Nigel Gresley of the Great Northern Railway had designed and patented his own application of conjugated valve gear (late 1916) which required further development to enable it to be applied to three cylinders of differing inclination. Gresley was involved with ARLE and he and Holcroft met at the former's office at King's Cross in January 1919. Holcroft schemed out a practical proposal to allow the Gresley valve gear to operate the inside valve and retain valve events at their correct relationship, by skewing the cylinder and valve axis."

 

Developed as part of his payed employment. I doubt he was paid for it. If that were true, it might explain why the LNER was so impoverished.

Irony?

 

I will need to check my figures to make sure (as any good historian should), however I think attributing the LNER's relative wealth issues to Gresley and the conjugated valve gear is, to put it bluntly, wrong.

 

FAS Brown quotes HNG as saying that Holcroft “has given me the key to the whole situation”.

 

I wasn't. I was attributing it to the LNER's possible unnecessary generosity! You would make a good spin doctor.

 

That is still, to be blunt, wrong. If you had done the research I've done you'd understand that the LNER finances (as with all large companies) are far more complex at a base level of patent use, let alone paying their own staff for the use of the patents.

Please leave personal commentary for somewhere else. It's unnecessary.

 

Sorry, what does "the LNER finances ... are far more complex at a base level of patent use" mean?

 

I don't know how I can break it down any more than the LNER's finances are more complex than a simple supposition that Gresley was paid per use of his patent by the LNER.

 

I did use the words "if" and "might". Perhaps they mean something else to you?