Sir Nigel Gresley CBE (19 Jun.1876 – 5 Apr.'41) was a British railway engineer. He was one of Britain’s most famous steam locomotive engineers, who rose to become Chief Mechanical Engineer of the
I visited the Flying Scotsman in New York on it’s tour in 1969. I’ve also seen the statue of Gresley, I think a Mallard would have been a nice addition but that sure wasn’t my call. King’s Cross has been renovated and is as nice as St. Pancras. There is evidence of bomb damage from the Blitz that you can see here and there.
I hate to say it, but I can’t imagine very many ways to put a duck in this composition without it getting peculiar:
(Photo by Alan Stanton)
If you had him holding the duck lovingly … it might be hard to make any railroad connection as to why he was there. Having him hold a model of Mallard lovingly … a little better but still odd. Sticking those things on the floor next to him just wouldn’t work…
BTW, Mr. Klepper needs to tell Mr. Sattler that he has succumbed to propaganda. Mallard never reached 126mph; that was an artifact of the hydraulic dynamometer gear and acknowledged by Gresley as such; the correct number is 125, which itself was only reached for a comparatively short time. This may seem like a little thing, but you will note that among other things, the exaggeration eliminates the DR 05 class from ‘holding the record’…
I might add that the ruined-big-end issue is largely immaterial; a corrected design that I think would have tolerated the record-run loads was quckly put in place for the remainder of the A4s’ lives. Less easily solved are the issues of whip and multiplying clearances in the conjugating gear that overloaded the inside big end in the first place.
There’s some that say this locomotive broke “The Ton” in 1904. It’s in dispute and I imagine rail buffs across the U.K. would discuss it for hours over a pint at the pub.
https://en.wikipedia.org/wiki/GWR_3700_Class_3440_City_of_Truro
About 10 years ago I was on a trip pulled by the Truro at the Mid-Hants railway. It’s been retired but damn, it was a fine looking machine.
How is a 3rd valve gear placed if one is not using the conjugating arrangement?
Chapelon’s 242-A1 placed a second eccentric outside the wheels that was connected to the Walschaerts expansion link and combination lever inside the wheels? With the connection through a “rocking lever” style bell crank?
Was this the usual way to do this?
No few designs put it in between the frames, driven either by a crank in the axle or eccentrics. Both the original and rebuilt Bulleid Pacifics show some ways of doing this. Note that the levers for Gresley (or Holcroft) can be located behind the cylinders if locomotive length and wheelbase permit.
Porta apparently had some discussion of ways to implement this on a 100mph engine in his long dissertation to the A1 Trust in the early Nineties – I suspect peppered with words in CAPITAL LETTERS. The issue with hanging the ‘third gear’ off one side of the engine is that much of the cross-augment becomes more difficult to address, and compensating via a balanced eccentric crank and bobweight on the ‘other side’ of the affected driver pair just makes the overall augment larger. (In partial defense of the idea, if the hammer-blow eccentricity is reduced, the absolute effect of coordinated augment (both wheels ‘hammering’ together’ as it were) can allow surprisingly high road speed, as in the last generation of English 2-10-0.)
Examples of a ‘good’ third-valve-gear setup are epitomized in some of the late UP Nines and the postwar Polish 4-8-2s; there are of course other examples. Of course there are benefits in driving all three valves from the rear, and in general the valve chest for the center cylinder (whether or not it is angled so its connecting rod ‘clears’ driver lateral-motion cannon boxes, a more serious constraint than what is possible with the usual cranked-leading-driver axle setup) will be tilted over to the side where the ‘third gear’ is located to minimize the bell-crank arrangement.
There have been some experiments in using different geometry for conjugation. One notable idea tried in Australia was to use rotating shafts rather than levers to get aro
There have been some experiments in using different geometry for conjugation. One notable idea tried in Australia was to use rotating shafts rather than levers to get around the issues of lever deflection and progressive lost motion. The problem – imho easily predictable – was that in the original application the shafts had too much of the wrong kinds of torsional flex. My version of this would use fairly large-diameter ‘pipe’ for the shafting (and ratcheting-cage rolling element bearings) – think of this as the extreme version of a hollow axle – and probably intermediate large-diameter roller bearings rather than ‘split’ to control any bending deflection.
There were two quite different applications of “rotating shaft” conjugated valve gear in Australia.
The first was used on Victorian Railways 4-8-4 H 220, which is fortunately preserved, if not in working order. This was a German design dating from 1915 which predated the Holcroft design adopted by Gresley. In fact, Gresley’s first three cylinder locomotive used a version of the German design, which was patented by Henschel One assumes the arrangements for using the Henschel design in Victoria were settled some time prior to 1941 when H 220 appeared. The cross shaft on this locomotive appeared to be around !0 inches in diameter which should meet the “hollow axle” description.
Some history and description of Holcroft’s design as adopted by Gresley can be found at: