Talk:LMS Stanier Class 5 4-6-0 4871

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Photographs

We have a fair few photographs of 44871 - I see no reason to include this one . I will give reasoning because otherwise we're going to get into another revert war, but this is clearly too dark (the technical term is underexposed). A black engine, at night, not lit. That should have been predictable. The only reason it was in the article was that it was inserted by its author. If anyone has any objections to its removal please try to help me understand the illustrative value of this image. Tony May (talk) 16:32, 15 March 2019 (UTC)[reply]

Hi Tony, I've just tweaked the said photo on Commons to bring up detail and adjust the tonal range. Thought I'd mention, since the image here automatically got replaced when I did this, leaving your comment alongside a changed image. It's still a bit dark, but not quite as useless as the original :) Cheers — Hebrides (talk) 13:36, 16 July 2022 (UTC)[reply]

The original may be viewed at commons archive. --Redrose64 🌹 (talk) 16:17, 16 July 2022 (UTC)[reply]

Steam from the firebox

I've seen this pair of locos today pulling a rake of BR Mark 2 carriages as they work the West Coast Railways. What I'm curious about is there appear to be a couple of vents above the firebox with steam coming out of them on both locos. They could be steam pressure vents, but wouldn't they be above the boiler or on the steam dome? They can be seen in the photo on this page. FreeFlow99 (talk) 15:29, 20 April 2024 (UTC)[reply]

@FreeFlow99: Do you mean in this image? That's the safety valves, steam escaping here shows that the boiler is up to its working pressure. --Redrose64 🌹 (talk) 18:31, 20 April 2024 (UTC)[reply]

@Redrose64. Thanks. I now realise that the water tank extends above the firebox, so it makes sense now. FreeFlow99 (talk) 15:57, 21 April 2024 (UTC)[reply]

Eh? The water tank is in the tender, behind the cab. --Redrose64 🌹 (talk) 21:49, 21 April 2024 (UTC)[reply]

I should have said that the boiler extends above the firebox. FreeFlow99 (talk) 17:44, 22 April 2024 (UTC)[reply]

In virtually all steam locomotives built after about 1830 (apart from some experimental types), there is always some part of the boiler which is above the top of the firebox. This is so that the firebox is entirely surrounded by water, except at the bottom where the ashpan is. See this diagram: the parts of the boiler that contain liquid water are coloured green, and those that contain steam are coloured orange. Notice how the firebox (at right) has water (green) above, in front and behind - it also has water to left and right, not shown on the diagram, but consider this cross-section, which unfortunately does not show the water level (it would be between the upper two horizontal lines). If the water level were to drop so that the crown sheet (the plate forming the top surface of the firebox) was in contact with steam instead of water, its temperature would rise dramatically, the plates would weaken, and a boiler explosion could result. On top of the boiler, above the firebox, are two safety valves - these release excess pressure, but cannot prevent an explosion due to an uncovered crown sheet. The fusible plugs guard against that, they are made of a metal which has a lower melting point than the firebox metal. If the crown sheet is uncovered, the rise in temperature melts the fusible plugs, and the firebox immediately fills with steam, putting the fire out.

In the case of the LMS Stanier Class 5 4-6-0, the firebox is of the Belpaire pattern, where the boilerr has a flat top above the firebox. --Redrose64 🌹 (talk) 21:01, 22 April 2024 (UTC)[reply]