DenysW

I can accept that the Gölsdorf axle was a touch crude, and that better was available (but without any UK designer pushing it), but would it and/or the alternatives have been enough to free Nigel Gresley into designing his P2 Edinburgh-Aberdeen expresses as duplex 4-cylinder 4-4-4-2s, say, instead of 2-8-2s. I'm thinking engineered not synchronous so as not to revert to 2-cylinder hammer. Unrelated topic: those KDL tenders do appear to have better sight-lines than the UK or US norm.

Would use of the Gölsdorf axle have converted some of this thread's more powerful creations from imaginary to buildable? It does seem to have made a reality of the Wurttemberg K class (DRG 59) of compound 2-12-0 bankers, but not to have been enough to make them a good choice on the flat. Were they just too foreign/metric for us gallant Brits? Sadly there is a model of the K class available (in DRG livery), so no kit-bashing is required. They also seem to have signalled the end of new articulated designs in Germany.

The Bavarian design is a compound Mallet with a huge tractive effort, but maybe not the grate or boiler to support it for very long. Presumably long enough for the banking duties relevant to the Bavarian branch lines. Sir Douglas posted the Kitson Mayer version proposed to Derby: back down to about 40,000 lbf tractive effort, and a similar sized grate to the Bavarians. Smoke seems to be an issue with banking engines that work through tunnels. The LNER Garratt is reported as working tender-first on the Worsborough bank as frequently the third locomotive in the tunnels. The Virginian Railroad also used bankers (see its AE class - massive power, but 8 mph, and 30 tons/axle) and also had problems with smoke in tight-fitting tunnels. The Lickey Bank seems straight(ish) and tunnel-free, so I'm surprised the LNER Garratt had issues. The LMS Garratts were preferentially run conventionally - tender-first apparently giving issues with coal dust. Covers were tried without much success.

LMS Garratts on the Lickey Bank. Well LMS had a chance to, and didn't. About the same tractive effort as the original Lickey Banker, much longer, and a generally bad fit with sheds across the network for coaling, watering, and ash dumping. LNER's Garratt was tried in the 1950s after the Worsborough Bank was electrified, and was not successful in the new duty. Same results, much more coal seems to have been the summary.

No problem, flying pig. One reason I like this site is that people disagree and correct - without trolling. It's never personal.

Not sure about the loading gauge as I don't think the German platforms were as high as ours, so the cylinders might be an issue. The Bavarian railways did start with imported British locos, so I assumed the differences would be tolerable. The axle loadings at about 16 tons don't look excessive. Top speed of 40 kph, so a design pretty specific to banking. It's reported as about 1.1 - 1.2 MW output (depending on which batch), with a starting tractive effort greater than 70,000 lbf (depending on how you calculate the compounding). With the possible exception of some of the US logging locos it's the most powerful tank I've seen. The grate is a surprisingly small 25 sq. ft., so that may limit its usefulness.

For the Lickey Bank, I'd have like to have seen whether the Maffei 0-8-8-0 Tanks coped with the duty. There are some signs of them having been a vanity project (as: my Bavarian tank engine is more powerful than your Prussian tank engine), but 25 were built and mostly survived through WW2, pretty much in banking duty. There are HO models, so no need for kit-bashing unfortunately. I also note that the Maglev connecting Birmingham International station to Birmingham Airport has been rebuilt rope-hauled.

Following on from Corbs' splendid turbine-locomotive images, would an LMS turbine Johnson 4P 0-6-0 have worked in terms of reduced coal consumption? According to Wikipedia, Stanier 'reluctantly' sanctioned construction of the last 45 Johnson units at the Operating Division's request, even though the Black 5 design was available, and had about the same tractive effort. LMS 6202 did give 6% lower coal use with a turbine optimised for 75 mph; would the Johnsons have been appreciably better than this if only required to do stationary to 25 mph with loaded wagons, and maybe 50 mph returning with empties? And then triggered development of selectable gears (changed manually with the loco stationary) to cope with the different duties, and with reversing? LMS ended up with just under 1000 Johnson 4Ps, so increased efficiency could well have been justifiable. Not sure about the Whole life Cost aspects: the turbine element might only have had the 10 year life of LMS 6202.

I'm quoting starting tractive effort because that's what I'm sure of in the Gresley design that was actually built. I suspect the truth mixes in some politics (my newest express loco is more powerful than yours, LMS), with big starting tractive effort to make sure the train can both start and accelerate up the ruling gradient, and then have sustained power at high speed. Two of these I can't put the actual specification numbers to, hence my emphasis on starting TE. As all of the express locos cited above were in the 35-45,000 lbf starting tractive effort range, with no grate bigger than 50 ft-sq, I also believe that all of the designers were under (probably financial) orders not to go for mechanical stoking - as that requires a different size of coal, so would trigger disproportionate spend, inconvenience etc. As also potentially the need for new turning circles if Gresley had gone the traditional-layout Garratt. Apologies for slip-shod use of jargon re mikados and moguls.

A quick look on www.lner.info ( a ) completely agrees with these posts on boosters , ( b ) reports them as ineffective above 30 mph, and ( c ) in need of drivers experienced in the use of boosters to get the low speed benefits . Underwhelming presumably down to small wheel size? Also tried , with the mixed results, shortly before the the Edinburgh-Aberdeen design was started, so the conclusions would have been available to the team that ended up going for a mogul. My alternate reality was to split the 8 driving wheels, permanently engaged, using articulation. The booster experiences could have been used either to "prove" or to "disprove" the articulated concept, depending on preconceptions.

All comments accepted as valid. You'd also need proper articulation to transfer enough of the weight to the rear driving wheels. I was merely musing about what other compromises were available other than going for a 2-8-2 mogul (up from a 4-6-2 pacific) when the spec calls for a 25% increase in starting tractive effort compared to LNER pacifics. The 4-4-2 + 0-4-4 version keeps you at 8 driven wheels, with the shorter driven wheelbase, but gives you the articulation and 6, smaller, cylinders. So a different compromise. I suspect the locomotive committee, despite passing all of the detail variants on the mogul they let through, would have choked on the lack of reference designs for express articulated locos.

This mostly is a question repeated from several comments on this thread about the Gresley P2 2-8-2 Edinburgh-Aberdeen express design that didn't seem to me really to receive answers at the time of asking. Why didn't Gresley go for a 4-6-2+0-4-4 reverse-Mallet/Engerth/Garratt hybrid. (Or a 4-4-2+0-4-4 if proper engineering calcs would have shown it wouldn't suffer from wheelspin). Due to my limited IT skills the attached picture is a cut/paste from a Hornby picture of one of their models, but it appears to show that the total length wouldn't need a drastic extension if you got rid of the classic-Garratt front water tender. I realise this does not address the bigger boiler to get to the P2 design starting tractive effort, or the loss of tender volume to the wheels and drives. Is there something simple I'm missing that would rule it out? It would (probably) not infringe on the Beyer, Peacock intellectual property as that was based around the use of a Bissel truck at the smokestack end and consequent use of the water tender as a counter-weight.