I have been studying photos of a number of British six drivered tank steam locomotives, and note that they have connecting rods, but no steam chests or main rods. How do these locomotives actually work?
The cylinders are inside, with the main rods connected to the cranks on one of the the axles (something like a crankshaft in a car). Three and four cylinder steam engines have two outside cylinders, such as you are familiar with and a similar setup for the inside cylinder(s).
John
With the last of the 9F Decapod 92220 Evening Star having been delivered in 1960 British Rail decided to abandon steam as quick as possible or impossible - no matter what ever!
So, scrapping sometimes tended to be quicker than service and thus it happened that certain engines still needed had to be retrieved - if possible - from the torch already starting to take it's bite.
As long as the boiler had not been touched, some engines were put back to work without con rods and even without cylinders. Of course such engines could only do light secondary work, such as picking up parcels and goods carriages or - as it was often called in Britain - minerals. Probably this was essential as I would imagine these poor hard bitten engines suffered severely from lacking minerals.
It seems however, the damage must have been half as bad since from old builders pictures it appears some vintage 4-4-0s and 4-6-0s have been 'equipped' with this apparent deficiency right from the beginning. It has been explained by sources usually badly or totally misinformed that this had been due to an epidemic shortage of cylinder castings in the United Kingdom during a time. Anyways, it seems at least this time the dreadful Hound of Baskerville was not responsible. However, even Sherlock Holmes had never been able to completely solve the riddle of these strange proceedings.
Some Continental European railways are supposed to have asked how on earth it was possible these 4-4-0s and 4-6-0s ran trains in spite of the obvious deficiencies and if doing without cylinders would save steam and coal - but reportedly they were discretely advised it was all by a very special and very British agreement between the Crown and Physical Laws involved and the matter would simply not work outsides of the British Isles.
However, I was never fully convinced of all this and have never gotten over a haunting suspicion there might be cylinders, con rods and even valve gear (!) involved, only they would somehow have been hidden from view. And, what do you say: when visiting York National Railway Museum during a stay in Britain my wildest imaginations were confirmed: cylinders, pistons, cross heads, con rods, valve gear - Stephenson's even! - and valves were all there, packed between plate frames and hidden from view yet working conventionally without any mythical contract with physics ...
Regards
Juniatha
(folks, before you start hacking your keyboards:
it was but a joke - just let technical history put a smile on your face)
Edit: a few words; color and font size
To Juniatha: Well done, M'Lady! I got a good laugh out of this one, and after the week I had I sure needed one! Look, my stomach's settling down, I'm regular again, ahh, life is good!
The book "How Steam Locomotives Really Work" by Semmens & Goldfinch, Oxford University Press, may be of some help to you. It's mostly about Euro locos. I'll sell my copy if anyone is interested.
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