Talk:Dead centre (engineering)

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This article is written in British English, which has its own spelling conventions (colour, travelled, centre, defence, artefact, analyse) and some terms that are used in it may be different or absent from other varieties of English. According to the relevant style guide, this should not be changed without broad consensus.

British English

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Please create an edit notice for the article, placing in it the template {{British English editnotice|form=editnotice}} Thank you. Lwarrenwiki (talk) 16:13, 16 November 2015 (UTC)[reply]

Done. Favonian (talk) 17:37, 16 November 2015 (UTC)[reply]

Question Why did this article use British English (centre vs center) when every single citation in the article, every other disambiguation and wiki dictionary use American (center as opposed to centre)? The programmer in my dislikes inconsistencies. — Preceding unsigned comment added by 66.37.242.79 (talk) 14:52, 14 September 2018 (UTC)[reply]

Oversimplified and just plain wrong

There is still quite a lot that this article leaves out, or gets wrong. It needs to be expanded to deal with the more general cases, without making it unapproachably complicated... which is challenging.

I've just removed the (false) assumption that a steam locomotive has only two cylinders. But there are some trickier issues with the current version as I write.

I'll try to get back to them, but if anyone else wants to have a go that would be welcome! Andrewa (talk) 08:54, 16 November 2016 (UTC)[reply]

Reciprocating engine

In a reciprocating engine, top dead centre of piston #1 is the point from which ignition system measurements are made... No. Many reciprocating engines don't have ignition systems, steam locomotivess and diesel engines, for example, and others. Similarly, the heading of this section is wrong... it's about internal combustion engines (and even then not quite right). Valve timing is also measured from #1 TDC.

Finding the volume of the cylinder using TDC and BDC and multiplying it by the number of cylinders will give the engine displacement. Sort of... the stroke is the distance between TDC and BDC, and multiply that by the bore (halved and squared and multiplied by Pi) and the number of cylinders... Not really close, is it?

And it's just sort of assumed that by top we mean furthest from the crank, even if the cylinders are angled or horizontal, in a boxer engine for example. Which is true, the timing marks on the VW beetle fanbelt pulley for example are always quoted as degrees "BTDC" and it means before when piston #1 is furthest from the crank. I guess even an inverted engine would stick to this convention, it would be good to check. But it's interesting that the opposite claim is then made for steam engines, see below. Andrewa (talk) 08:54, 16 November 2016 (UTC)[reply]

Steam engine

As steam engines are commonly horizontal... No. Well, maybe. Not a helpful statement... I guess there are and have for a long time been more horizontal ones than vertical ones, but it's a guess and a misleading one at best. Reciprocating marine steam engines and large stationary steam engines, once common, were typically vertical, see beam engine. And marine steam engines now are typically turbine, for which the term horizontal has a completely different meaning (they all are horizontal AFAIK, that much is true) and there's no dead centre at all.

...the relevant terms are front dead centre and back dead centre rather than "top" and "bottom". Interesting claim. Unsourced. May be true. Certainly isn't true for internal combustion engines, see above, and maybe this should be pointed out in the article if there really is a difference. It would be good to check the correct terminology for steam locomotives, the designers of the valve gear might use it for example. Andrewa (talk) 08:54, 16 November 2016 (UTC)[reply]