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Build a Bodmer competition (not)!


5&9Models

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In 1845 the Swiss engineer John George Bodmer constructed a pair of 2-2-2 locomotives at his Manchester workshops for the Joint Committee of the Brighton, Croydon and Dover Railways. Born in Zurich in 1786 and later apprenticed to a millwright, the young engineer showed much promise and a strong talent for innovation. He moved to Lancashire in the 1820s but continued his connections with Switzerland and Baden in Germany. His particular invention was that of an opposed cylinder steam engine in which two pistons moved in opposite directions driving two crankshafts, a 'balanced' engine. He continued to expand this idea and the two locomotives for the Joint Committee were his most famous, or perhaps infamous, machines.

 

Purchased for £2100 the Committee took delivery of the engines in July and December 1845 and numbered them 123 and 124. The locomotives each had a pair of double pistons, the conrod of one passing through the hollow conrod of the other. This complicated arrangement was powerful but very costly to maintain. The tenders supplied were carried on six wheels with a mechanically driven feed pump mounted between the frames to feed the loco via a substantial hollow pipe which also served as the coupling between tender and loco! Typically the loco itself had no brakes but the tender sported huge wedges of timber with iron shoes which when wound down, wedged themselves between the wheels and the rails which in extreme circumstances could lift the tender clear of the rails altogether. Predictably this had disastrous consequences and the engine allocated to the SER after the dissolution of the Joint Committee left the rails at Pluckley on the 23rd May 1846 killing the driver. However a subsequent enquiry proved that a large stone left on the line by errant youths was the cause of this particular accident. Unfortunately this did nothing to assuage the opinion that this 'foreign' locomotive was more trouble than it was worth and after some modifications and very little further service the loco was sent to Ashford where it languished until being dismantled in 1880.

 

The Brighton engine had better luck although it was rebuilt first by Craven, then again by Stroudley who even saw fit to name it 'Seaford'. Thankfully a photo exists of it in this guise but it can be seen that not a great deal of Bodmers original design survived, certainly not his balanced pistons which did not survive the Craven rebuild.

 

And so to the model. A friend of mine declared that he was going to build Seaford which prompted my response that i was intending to build the 1845 version. "Let's build them simultaneously and do a joint article for the HMRS" he said. "Great idea" I replied not fully aware of what I was letting myself in for.

 

Nevertheless the short straw had been drawn and everything else put on hold to scratch build Bodmers 1845 balanced locomotive in 4mm scale to EM standards. Since nothing about it is conventional it has tried my patience to the extreme and progress in painfully slow, however I hope the following photos show that it is at least getting somewhere and I hope to be able to add to this blog in a positive manner in the not too distant future.

 

If you never hear from me again you'll know it didn't go well!

 

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Portescap gears in a scratch built box to get them in the right positions.

 

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It fits, just!

 

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Haycock firebox. I hate doing these....!

 

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Frames and springs. The trailing springs were double coil springs hidden in the axle guide casting as per the tender.

 

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The story so far.....

 

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Thanks for looking!

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A very good start , the brasswork is excellent. 

 

Not a prototype I have seen, but it really is very unconventional. Those frames made out of a stack of flat bar must have given the builders a bit of a headache, but they look great on the model. 

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Indeed, the frames were laminated timber! Several layers of steamed and bent wood (I can’t remember the variety without looking it up) sandwiched between wrought iron plates top and bottom. Various bolts held it all together. It must have flexed an awful lot but perhaps that wasn’t necessarily a bad thing given the apparent ultra smooth running of the balanced engine.

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Heh , I'd never have guessed at timber. Must have almost been like secondary suspension. 

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Holcroft, in one of his books on GWR engines, talks about watching sandwich frames flex as locos went through pointwork. It seems to have been one of the reasons for chosing them on GWR locos running on the rigid baulk road track  as they gave a bit of extra suspension as mentioned. 

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14 minutes ago, pete_mcfarlane said:

Holcroft, in one of his books on GWR engines, talks about watching sandwich frames flex as locos went through pointwork. It seems to have been one of the reasons for chosing them on GWR locos running on the rigid baulk road track  as they gave a bit of extra suspension as mentioned. 

 

Although traditional sandwich frames are plated either side, these were plated above and below so must have beee even more flexible. I find the use of laminated timber beams way ahead of its time. The sort of thing you expect in modern architecture.

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Or the wing spars of WW2 vintage De Haviland aircraft.

 

I guess the question here is whether it was an original idea of Bodmer's, or was adapted from somewhere else. 

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29 minutes ago, pete_mcfarlane said:

 

I guess the question here is whether it was an original idea of Bodmer's, or was adapted from somewhere else. 

Really interesting question although we can be sure it wasn’t from DeHavilland. The thing about that period was that it was such a frenetic time of experimentation, many of these engineers would try anything, often to get around a problem that didn’t exist in the first place. A lot of Bodmer’s personal archive still exists with the family. I wonder if there’s anything in there that would explain his reason for making frames from laminated wood.

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Exciting loco! Very impressive build. Can I ask how you created the effect of the laminated frames? They aren't actually laminated, are they?

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17 hours ago, Mikkel said:

Exciting loco! Very impressive build. Can I ask how you created the effect of the laminated frames? They aren't actually laminated, are they?

Thanks. Indeed they are. It’s nickel silver strip soldered in a bunch at one end then gently soldered, bent, coaxed and soldered a bit more until I got to the other end....I never want to do it ever again! :wacko:

 

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Superb modelling and I do like the way you have laminated the frames as in the original.  These 'odd ball' prototypes are amazing and there's nothing like building a model to appreciate their 'look and feel'. 

 

There is a fascinating PhD thesis by P.S.Bardell on balanced locomotives, which can be downloaded from Imperial College

 

This includes an even more challenging prototype - Ritchie's New Locomotive Engine, which which had apparently been seen in steam at Kew and appeared in the very first issue of 'The Engineer':

 

2110504277_RitchiesImprovedEngine.jpg.a68c7ff379e5aa1727e05fc8a8941380.jpg

 

Your next modelling challenge, perhaps?

 

Mike

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3 hours ago, MikeOxon said:

Superb modelling and I do like the way you have laminated the frames as in the original.  These 'odd ball' prototypes are amazing and there's nothing like building a model to appreciate their 'look and feel'. 

 

There is a fascinating PhD thesis by P.S.Bardell on balanced locomotives, which can be downloaded from Imperial College

 

This includes an even more challenging prototype - Ritchie's New Locomotive Engine, which which had apparently been seen in steam at Kew and appeared in the very first issue of 'The Engineer':

 

2110504277_RitchiesImprovedEngine.jpg.a68c7ff379e5aa1727e05fc8a8941380.jpg

 

Your next modelling challenge, perhaps?

 

Mike

Thanks Mike, that’s fascinating. It’s very reminiscent of W.B.Adams first locomotive designs a decade earlier. Both engines after the same result, steady running, low centre of gravity, balanced reciprocating masses etc. I’ve not seen that image before so it’s of great interest. As you rightly say, these things need to be modelled. I’ll add it to the list!

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At last it's complete (more or less). 

 

I have to say this build has been the most complicated I have done to date. Perhaps I've been trying to be too clever in fitting a Portescap motor and gears in the loco. There's really only just enough room (and if I'm really honest there isn't)! 

 

In hindsight tender drive would have been much easier but at the time it seemed like a cop-out. The next few locos I build are even smaller so I plan to develop a little motor bogie to install inside the small four wheel tenders required for the two Rennie locos likely to be the next projects. Onwards and upwards!

 

In the meantime I'll just leave these images here and take some time to recover from this build. It's been a roller coaster of emotions to say the least. Thanks for looking.

 

Bodmer at BA 01.jpg

Bodmer at BA 02.jpg

IMG_4266 copy.jpg

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Terrific! :). I hope you feel the time and effort was worth it? It looks to me as if it was, but then no-one can feel another's pain... As you say, onward and upward :good:

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58 minutes ago, Chas Levin said:

Terrific! :). I hope you feel the time and effort was worth it? It looks to me as if it was, but then no-one can feel another's pain... As you say, onward and upward :good:

 

Thank you. It was a struggle this one but I learned a lot from it, mostly about my limits!

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