Discussion in 'Steam Traction' started by aron33, Aug 15, 2017.
There appear to be two oddball castings in the eight.
Trick valves have double ports on the admission side. It's basically a way of increasing the port area on the steam inlet side; you have two ports opening when the valve opens to steam, but only one opening on the exhaust side. Remember than with a basic zero exhaust lap valve the exhaust port is open for 180 degrees no matter the cut off (although the amount by which it opens varies and changes phase with cut off), but the steam port is only open for your cut-off period. So somebody (Trick, perhaps) got the idea of doubling up the admission ports to compensate. They'd obviously forgotten that inlet steam is at much higher pressure and thus lower specific volume than exhaust, so you really need to look at freeing up exhaust events too. A good admission phase and poor exhaust is liable to lead to high back pressure and a loud exhaust.
Later on, the LMS tried double porting the exhaust side, so they didn't have to resort to the dreaded long lap valves that were clearly causing SR Moguls, GWR standard engines, and indeed Fowler 2-6-4Ts to fail left, right and centre (sarcasm alert). These weren't hugely successful by all accounts, apparently due to the secondary ports coking up, although they were reputedly fitted to a Urie N15 by Bulleid (755, The Red Knight), which became quite well regarded.
In France, the Willoteaux piston valve was developed, with double porting for both inlet and exhaust. These were used on at least one successful class, the 141P mixed traffic compounds, as a way of getting better port openings without having to resort to very long travel gear. Most of these valve types have the disadvantage that the secondary ports are liable to be rather constricted; later developments seem to have ignored them in favour of grasping the nettle of good lightweight valve design and large travels.
I'd include pictures, but I can't find any right now.
Well, they do say "rugby is a game for gentlemen with odd-shaped balls"...
In terms of odd shapes IIRC, the website says that the engine has a different design of axlebox for each axle
The Holden F5 team just installed 789's cylinder block into the frames today. Looks fantastic.
Colonel Campbell-Masterton the MAstodon if we go for famous players?
Gareth Edwards, Rex Willis, Lewis Jones, Malcolm Thomas, or Cliff Morgan would suit nicely
You'd have to be careful running some of them through Wales...
I always thought Moriarty was an excellent name for a rugby player with an, ahem, physical reputation... (he played both codes)
I repaired an ancient 2-4-0 Sharp Stewart of 1877 and we built a cilynder block quite exactly. Nice to see!
Here you are our new block. This was by 2012.
Good work Sir! Is the Locomotive complete now, or are you still rebuilding it?
It was almost finished by 2012 when the customer stop paying and...since now.
Maybe the Rw Museum at Madrid wants to recover it and we have the oportunity to finish completely the repair.
Anyway it's a pity. Steam preservation in Spain (broad gauge) is almost dead.
That's a real shame. I hope one day the situation can be resolved and the engine completed.
Is there a picture anywhere?
4709 now has a cylinder cast, so on to the other one.
Also suggests that the design has been amended to make her more gauge friendly and that main line running is still being considered for her, which would be great.
No point in closing that particular door until you have to...
This was noteworthy: "the team re-engineered the casting process for steam cylinders with poly patterns from first principles. It’s taken a year of hard learning and steely determination".
If in fact another major element of the industrial infrastructure of steam is now available again, that's excellent. (I know, other cylinders have been cast recently - I don't recall if any used poly patterns though - but spreading the knowledge/capability through a new generation is still to be lauded.)
There are new cylinder castings for the C class at the Bluebell that were made using poly patterns
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The Wainwright P class cylinders were done that way; also as @RLinkinS says, the replacement C class cylinders.
As have those for Charwelton. I'm sure that if you start looking, you will find a good few more, as well. The rarities will be ones cast using traditional wood patterns. Lambton No.29 is one.
Is it known where these were cast? As I understand it, previous GWR cylinder castings ( for 4930, 6880, 7802 & 3850) were all cast at Shakespeares, now no longer in business. All with wooden patterns...
Pretty certain they were done at Premier Patterns.
Edit: a bit more info http://wainrightsfinestsecr27.blogspot.com/2017/11/cylinder-patterns.html and http://wainrightsfinestsecr27.blogspot.com/2017/12/cylinder-manufacture-time-line.html
One of the interesting things is that a set of 1:8 cylinders was 3-D printed from the same drawings that were used to make the full size patterns: that enabled both a quality check of the drawings, and an interesting talking point for fundraising events!
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