Steam speed records including City of Truro and Mallard

I think the comment was about the largest coupled wheels.

Largest somewhat conventional single drivers (in this country at least ) were I believe the Pearson Bristol and Exeter 4-2-4Ts, some of which had 9ft diameter drivers:



Image source: https://commons.wikimedia.org/wiki/File:HLB_Lok_1.jpg

I think the (unsuccessful) broad gauge loco "Hurricane" had 10ft diameter drivers, though really all that loco proved was that Brunel wasn't much of a locomotive designer ...

Tom

 

and 61 001 the two cylinder tanklokomotive for Henchel Wegmann train.
This was known to be a dead end and the later 18 201 was built as three cylinder 1939.
Specifications for 05 and 61 locomotives was 160 km/h continious at 6 rps and that gives 2300mm.
The designer mr Wolf cried for 2100mm but in wain.

That was also the reason the germans had stopped dreaming of high speed steam before the Mallard stunt in august 1938.
In may 38 they had more Fliegender Hamburger and Koeln diesel sets and the timetable for the steam driven high speeders was eased to lessen track maintenance.
The unsprung high mass of drivers do uggerly things to rail and is more than a cube function of diameter. 05 002 drivers were more than 5 ton

Cox mentions somewhere that high unsprung mass is very harmfull to tracks and he knew and aprecciated mr Wagner and maybe had information from him.

 

Aspinall's L & Y 4-4-2 "Highflyers" had 7'-3" dia driving wheels, but there is a reference in the L & Y book to a N.E.R. 4-4-0 loco with 7'-6" dia driving wheels.

 

Ahh, missed that. Sorry!

 

The story of the Henschel - Wegmann zug is a bit more than that. The locomotive built in 1939 was a streamlined three cylinder 4-6-6 tank. This survived the war in East Germany and was rebuilt into the pacific 18201 during the 1960s with a new boiler standard with other East German locos and larger cylinders (said to have come from a class 45 2-10-2).

 

Tom, in defence of Brunel ( although he is IMHO praised more than enough ) “Hurricane” and
“Thunderer” were built by Hawthorns under a stipulation that locos should be no larger than 2-2-2.
Both locos consisted of a boiler carried separately feeding a 2-2-2 engine. In the case of Hurricane
with a 10foot dia. driving wheel. Hurricane lasted only a matter of months, the boiler being reused
elsewhere. The two locos design is attributed to T.E.Harrison.

I am uncertain as to whether Brunel actually was involved in loco design ( others may know)
but undoubtedly the early GWR was poorly served wrt motive power until the arrival of
Mr Gooch. I suppose as Brunel AFAIK specified what he wanted he might be held responsible
but…

The Bristol and Exeter 4-2-4 tanks ( first batch nine foot diameter drivers, later 8’10”) were
a successful design by James Pearson for the B&ER. One was timed by CRM at
c. 80mph down Wellington ( always quoted as 81.8mph despite the timing was by a
1/5th second stop watch ) relevant to this forum ?

The existing 4-2-4s were converted to 4-2-2 tender locos by the GWR ( post the B&ER amalgamation )
following a derailment at Long Ashton’s in 1876.

Michael Rowe

 

Brunel did not design any locomotives per se but provided a set of specifications that were essentially unworkable and led to things like "Hurricane", being an attempt to meet Brunel's criteria. Away from my books right now, but as I remember it: shortly after Gooch's appointment, Gooch was ordered to report to the board on the poor state of the locomotives. Gooch reported, with some trepidation, on the faults in Brunel's specs. The board accepted the report, Brunel behaved with equanimity and left Gooch to get on with it.

 

I wonder how that worked out... The builders presented a set of locomotives that were neither useful nor met Brunel's hopelessly optimistic specification. I can imagine that Brunel wasn't an easy man to tell that his specifications were unworkable, but you'd think there would have been some pushback from the people who actually designed and built them. I wonder if history records which, if any, builders were given the specification and declined to tender?

 

Interestingly there is an article in Backtrack about those locos this month. The TL,DR is that in the author's contention, they were to the design of TE Harrison and incorporated his theories about locomotive maintenance cost, viz that most of the maintenance costs in locomotives of the day was involved in disassembly / reassembly rather than the actual repairs; and separating the locomotive form the boiler made maintenance of the machinery much easier and therefore cheaper; it also allowed preventative maintenance in service by the driver much more easily; and could in principle allow repairs to the boiler and engine to be carried out separately, i.e. to have a pool of boiler-carriages that could be connected and disconnected as required to the engine-carriages. [My terminology].

Harrison managed the locomotives on the Stanhope & Tyne Railway and therefore would have been familiar with the costs of maintaining a fleet of locomotives on which to base his ideas. Though I can't help noticing that he cleverly got the risk of trying out his design theory carried by someone else!

Interestingly, and I hadn't previously been aware, "Thunderer" was geared at 2.7:1, such that the effective diameter of the four coupled driving wheels was 15 feet! 'Hurricane' had 10 feet wheels, directly driven.

The author also quotes a report, without further comment, from the Durham Chronicle of 31 August 1838, in relation to 'Hurricane' that "The fly-wheel of this engine is ten feet in diameter, and it moved at the rate of 150 miles per hour". It's unclear to me what that means, but the context was during an inspection by eminent engineers while the locomotive was still in the works at R&W Hawthorn, and possibly it was arranged to operate statically while jacked up off the rails while under construction. (That might explain usage of the term "fly-wheel". But it is supposition on my part).

Tom

 

Thanks, it is some years since I read the Gooch diaries. I suppose we should give credit to Harrison for
endeavouring in the “Hurricane” an# “Thunderer” locos of sufficient power within the 2-2-2 remit.
Even if to our 21st century eyes they appear somewhat bizarre.

Michael Rowe

p.s. have just read Tom’s posting re current backtrack. Thank you

 

Cornwall and others large diameter wheeled locos were single wheelers. Jon Lever's post referred to coupled wheel locos. I don't think he's wrong with his statement but am no expert on the subject.

 

Indeed. Certainly the largest coupled wheels in Britain, and I wonder if they were the largest in the world? Became property of LNER:

https://www.lner.info/locos/D/d18.php

The German Class 05 and 18.201 likely had the largest 6-coupled wheels. Among other 4-6-4 classes, there was a one-off Soviet type (class 2-3-2V) with 2.2m (7ft 2½in) drivers:

https://upload.wikimedia.org/wikipedia/commons/thumb/8/8b/2-3-2В.jpg/1200px-2-3-2В.jpg

And at least three types of American 4-6-4 had 7ft drivers:

https://en.wikipedia.org/wiki/Milwaukee_Road_class_F7
https://en.wikipedia.org/wiki/CNW_Class_E-4
https://en.wikipedia.org/wiki/Santa_Fe_class_3460

 

Thanks. Your post has spurred me on to delve a little.

Nock’s first publication of the 46251 log was in the June 1961 Railway Magazine. p.422
He refers to the run having occurred earlier and by implication had withheld publication,
but now feels able to
QUOTE “and with the agreement of the young Scottish friend who recorded it” END QUoTe

Nock then used the log in his “William Stanier a biography” published 1964.
The log is reproduced with 46251 on p.177 but in the text he refers to
QUOTE “ 6257 City of Nottingham “ END QUOTE I assume this is a typo i.e. ‘7’ for ‘1’
No log acknowledgement

The log is included in his “60 Years of West Coast Running” p.204
46251. No log acknowledgement

The PSL 1989 collection of RM Nock P&P articles includes exactly the same wording
and log as per the June 1951 RM

From this I conclude the loco concerned was 46251.

The Railway Performance Society archive includes Nock’s note books from 1950 to 1964.
The 46251 log does not appear. Confirming the 105 mph log was not timed
by him.

I imagine Nock would have used the log in the various books he cranked out
in his latter years but I do not have copies of these.

Regarding 46255 , the only occasion according to his note books Nock travelled behind
said loco was in June 1963. on a special ( there are also logs within the RPS archive
of this run, from other recorders )

I have also checked through all the logs within the archive featuring 46255 and
cannot find any logs twixt either Glasgow and Carlisle or Carstairs and Carlisle
with high speeds.

I have also carried out a trawl of Duchess/Coronation 4-6-2s logs over this section,
and cannot find any speed higher than 83 through Beattock, with speeds up to
90 mph afterwards. Nock was right to delay 46251 publication !

Can you please tell me where you read the 46255 105 mph claim. Thanks.

Michael Rowe

 

A book about the German railways which might answer some questions and possibly disprove others. Translated from German into English.

https://www.railadvent.co.uk/2024/0...ss-steam-locomotives-by-andreas-knipping.html

 

May I direct you to p.79 of The Evolution of the Steam Locomotive, which recalls a tale - undoubtedly of the tall variety - of a legendary high-speed exploit with this engine.

City of Truro eat your heart out.

 

This claim can absolutely get in the bin.

 

But I thought all GWR speed claims were totally irrefutable though...?

 

Its a clearly big fish story, and apart from anything else with the brakes of the time I bet they'd need a *lot* more than 3 miles to stop light engine. However one should note that with 10ft driving wheels it would only be doing 280rpm at 100mph, and with only 20in stroke cylinders the piston speed isn't all that high. If my sums are correct, though, it is a higher piston speed than the few recorded figures I could find for pre 1850 broad gauge locomotives.

 

The required evaporative rate to make steam to get up to that 100mph and then maintain for a meaningful distance is surely beyond the abilities of virtually every steam locomotive built between 1829 and at least 1900.

Please note - that’s just my opinion!

 

Sounds like you would not agree with the esteemed scientist Dionysius Lardner, who calculated that brake failure would cause an engine to reach 120 mph through Box Tunnel:

https://en.wikipedia.org/wiki/Dionysius_Lardner