Talk:Tappet

Image

I added the image of the camdrive in my car, but I'm not completely sure that this is the right image to use here. My car repair handbook calls these things valve lifters, but reading this article on tappets, it does seem that it is what the term tappet should refer to. The specific part I'm referring to is the metallic cylinder that sits between the actual cam lobe and the valve stem itself (the latter of which obviously isn't visible in the image, as the tappet covers it) in order to take up the sideways friction of the moving cam lobe (or at least that is what I'm assuming is its purpose). --Dolda2000 23:46, 5 October 2006 (UTC)

Diagram needed

{{Reqdiagram}} The picture shows a lot of complicated parts. It would be nice to have a simple drawing with the tappet(s) clearly labeled. -- Beland 08:23, 14 February 2007 (UTC)

These apparently include tappets, although I myself can't tell which bit is the tappet. --pfctdayelise (talk) 11:00, 10 August 2008 (UTC)

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Disagree with the opening definition

• I disagree with the current (March 9, 2010) opening definition of a tappet. I propose to replace it with the following: "A tappet in mechanical engineering is that end of a push-rod which contacts the cam. The cam turns, and when the enlarged part of the cam reaches the tappet, it pushes the tappet (and, through the tappet, the push-rod) away from itself. A tappet is thus a cam follower. There are various designs of tappet." This is based on examining Fundamentals of Motor Vehicle Technology, pp. 44 and following, and Light and Heavy Vehicle Technology, p. 49.
  • I would changed your definition to: "A tappet is that end of a push-rod which contacts the cam. As the cam turns it actuates the tappet, which actuates the push-rod. There are various tappet designs." The cam doesn't actually move the tappet away from the cam, it stays the same distance from the surface. Also, a tappet is more than a cam follower; see cam follower. Wizard191 (talk) 18:51, 9 March 2010 (UTC)
• I disagree with the second sentence, which currently states that "Properly speaking, a tappet is only that part of a rocker arm which makes contact with an intake or exhaust valve stem above the cylinder head of an internal combustion engine." In Fundamentals of Motor Vehicle Technology, p. 46, Fig. 8.17, and Light and Heavy Vehicle Technology, p. 49, Fig. 1.88 , the sequence is cam, tappet, push-rod, rocker, valve stem. The tappet is nowhere near the valve. I propose to delete this sentence.
  • Perhaps in the example given above the tappet doesn't contact the valve stem, but in OHC applications the tappet does contact the valve stem directly. Wizard191 (talk) 18:53, 9 March 2010 (UTC)
• I disagree with the final two sentences of the current opening paragraph, which say "Without a tappet (and with the cam acting directly on the valve), the sideways force would cause the valve stem to bend. With a tappet, the sideways force is transferred to the cylinder head so only the downward force acts on the valve stem." As noted above, the tappet is nowhere near the valve or its stem. I propose to amend these sentences to remove the implication that the tappet touches the valve stem, or that the cam could. UBJ 43X (talk) 11:00, 9 March 2010 (UTC)
  • See my note above. The sentence can be reworded to note that it is only applicable in applications where the tappet does contact the valve directly. Wizard191 (talk) 18:54, 9 March 2010 (UTC)

Newcomen Engine

If the Newcomen Engine is dismissed as a precursor to "true" steam engines, then so must early Watt engines. The early Watt engines used the incoming low pressure steam as a blanket to keep the cylinder warm, and used a separate condenser for the cold business. Since steam was used to create the vacuum, and the air was not modified in any way (contrast to a Stirling Engine), it is the management of steam that is the fundamental principle; ergo it is a steam engine. Martin of Sheffield (talk) 15:59, 29 October 2019 (UTC)

Steam engines

Hi Andy Dingley. Regarding your reasoning of "more specific term" this revert of yours, I believe that the broader term "Steam engines" is more appropriate. This is because the broader term is more likely to be understood by the average reader than "Beam engines". Cheers, 1292simon (talk) 23:45, 24 January 2020 (UTC)

• So you want to make it less accurate (enough of that lately!) just so that it's easier reading for some "average reader" who has never heard of a beam engine, yet is reading an article on tappets? This is why we link beam engine. If they don't know what it is (and not all of them are steam engines), then they have a whole article to read.

You will, no doubt, be about to add examples of these "steam engines with tappets" that are not beam engines. Andy Dingley (talk) 00:08, 25 January 2020 (UTC)

Hi Andy. Could you please be WP:CIVIL and drop the sarcasm? Yes, I believe that we should not assume that someone who happens to be reading the tappet article already knows about beam engines.

Regarding the beam engines which used tappets and are not steam powered, could you please give examples? 1292simon (talk) 21:44, 25 January 2020 (UTC)

Almost every non-rotative beam engine used tappets, so that's the early beam engines, and many of the later ones (the non-rotative ones, mostly low-speed), including Cornish engines. That's also the Newcomen (and Watt) atmospheric engines, and we shouldn't commit the error of calling those "steam engines" either. The water-powered beam engines mostly used tappets too. Andy Dingley (talk) 22:33, 25 January 2020 (UTC)

The error lies in not calling early atmospheric steam engines a form of steam engine. I raised this with you last October when you reverted an edit but you just ignored my response. This weird obsession of yours that an engine driven by the management of steam is not a steam engine unless it is a high pressure steam engine flies in the face of people such as Trevithick and Watt. Buchanan writing in Industrial Archaeology in Britain states: "the first effective steam engine was named 'The Miner's Friend' by its inventor, Thomas Savery" and later on the same page "A new type of steam engine was invented in 1708 by a Dartmouth blacksmith, Thomas Newcomen". If you prefer a learned society: "The Newcomen Society was founded in 1920 and takes its name from Thomas Newcomen, who invented the first practical working steam engine around 1712". Martin of Sheffield (talk) 23:46, 25 January 2020 (UTC)

• That's a separate issue, and this isn't a class on linguistics in which to cover the differences between an associative term ("Newcomen invented steam engines") and an ordinal term, where we describe Newcomen's engine (full of steam as it might be) as an atmospheric engine, in order to distinguish it from all the steam engines which came later.

But for the point here, it doesn't even matter: Newcomen atmospheric engines are still beam engines. That's the narrow class, not the broad class, and the only one to which tappet applies. We still shouldn't apply a hugely broad (and recognisable, so readers latch onto it) term like "steam engine" to what was only ever a group ("steam or atmospheric engines using tappets") which was from the narrower set of beam engines. Andy Dingley (talk) 01:05, 26 January 2020 (UTC)

• I agree with Martin that the sources above support describing atmospheric engines as steam engines. Regardless, the Steam Engines section now includes later steam engines which used tappets, as per Andy's request above. Cheers, 1292simon (talk) 11:49, 4 February 2020 (UTC)

• Except that you've now added Caprotti valve gear as using tappets, which it doesn't.

Caprotti gear uses cam followers. This use of 'tappets' is a back formation: because OHV petrol engines use cam followers, which are commonly described (and already somewhat problematically) as 'tappets', this led to Caprotti's cam followers (in a period when the petrol engine was already becoming dominant) getting described that way too. But that doesn't change that they're still an utterly different device to the tappets used in beam engines.

This is the same problem I keep seeing in all of your huge edits to engineering articles (I've raised this before, and I'd have raised it more often if the articles had been in a better state to lose): you're making edits which keep showing that you have no real understanding of the topics. You're Googling, finding a minor text string match (I'm sure Google thinks that Caprotti used tappets), then seeing that as a reason to describe unrelated things as if they were the same. This is anathema to an encyclopedia. Andy Dingley (talk) 12:36, 4 February 2020 (UTC)

• OK, so if you want to start edit-warring everywhere now, you are going to have to get your sourcing right up to scratch. From now on, your invented nonsense goes. Andy Dingley (talk) 13:07, 4 February 2020 (UTC)

• Hi Andy. I apologise for making changes related to an ongoing Talk page discussion, and for not noticing that the Caprotti uses finger followers.

  As per Martin's point above, the beam engines are a type of steam engine. Given that many readers are unlikely to be aware what a beam engine is, I think they should be described using the more familiar term "steam engine". Cheers, 1292simon (talk) 08:36, 6 February 2020 (UTC)

• It's not the heading "beam engines" that I objected to, it's the phrase "a precursor to the steam engine" that is wrong. Beam engines are a subclass of stream engines, and the appropriate phrase is "an early form of steam engine". Martin of Sheffield (talk) 10:06, 6 February 2020 (UTC)

• Atmospheric vs. steam (i.e. disjoint) is an important topic for some other articles, but it's just not important to this one. Nor do I see 'precursor' as problematic, because it's not strongly exclusionary. If you want to find some wording though which gets round that, then go to it - I'm not going to push the point here. Done

But we should stick with beam engines rather than steam engines, as that's a clear distinction and is relevant to whether tappets were used or not. Andy Dingley (talk) 11:24, 6 February 2020 (UTC)

• WTF is a "tappet valve"? This is what I mean - you just keep making stuff up. There is no such thing as a "tappet valve", there is no credible source which describes them. There are valves. They are actuated by tappets (which are not part of the valve (originally, for the beam engines as described here), they move relative to it (i.e. they're on the moving vertical rod, not the valve body or cylinder body)).

You might just about make a case (vaguely) for a "tappet valve" as a form of bash valve, but that's a different mechanism yet again. Andy Dingley (talk) 00:14, 8 February 2020 (UTC)

References

Internal combustion engines

Hello. I hereby propose to rename this section to "Piston engines", since the section does not apply to Wankel engines etc. Cheers, 1292simon (talk) 00:12, 8 February 2020 (UTC)

• Steam engines are also piston engines, as are compressed air and hydraulic motors too. The point of this heading is to contrast it to steam engines, the other section. No-one is talking about Wankel engines.

This would be a typically bad change. Andy Dingley (talk) 00:17, 8 February 2020 (UTC)

• Ok. Thanks for your reply. Cheers, 1292simon (talk) 03:50, 9 February 2020 (UTC)

Adjustment section

Once again, you're blanking large sections of relevant and sourced content. Please don't.

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You have given no explanation for this other than WP:NOTHOWTO. Yet this is nothing like problematic HOWTO content. It describes the process of 'adjusting the tappets', surely the only reason why almost any reader will have encountered this obscure word before. Now it's true that this process is hardly ever needed these days, but that's more reason why we have to give some explanation of it - it's no longer familiar to motorists. Also WP:NOTTEMPORARY. Andy Dingley (talk) 11:20, 13 February 2020 (UTC)

• Hi Andy. How do you figure that it is well sourced? The only reference in the whole section is regarding the crash which killed Alan Blumlein.

  I think there is some worthwhile content in the section (which primarily applies to OHV engines but the paragraph currently implies it is for all engines), but the tone reads as "this is how you adjust the tappets, and here is why it is important that they are correctly adjusted". Also, the last paragraph is putting WP:UNDUE weight on a design that was only used by a handful of American engines. Cheers, 1292simon (talk) 06:36, 14 February 2020 (UTC)

• Sourcing isn't a reason to delete content, WP:V is (if at all). The sourcing here could certainly use improvement but the obscure part (Blumlein) is there, the rest is almost at the self-evident level and needs little more than the nearest Haynes manual - it's so obvious that no-one (I haven't) has bothered to do so as yet. There's a lack of sourcing in the article current version, not sourcing that's easily available. There's a risk of HOWTO content, but we're not into that as it stands. The centre-stud design was widespread in Europe (Ford and GM operate outside the US!) for years, until OHC became universal.

The first thing to lose, if any, would be the 1930s image of the OHC with finger rockers - once we have an equally clear image of something like a '70s Ford Pinto with stud adjustment, rather than eccentrics on a rocker shaft (a very rare design). Andy Dingley (talk) 10:35, 14 February 2020 (UTC)

• Hi Andy. I agree that the 1930s finger rocker image should be replaced once a more representative image is found.

  Regarding WP:V, actually it states "Any material that needs a source but does not have one may be removed". My point is that you accused me of removing sourced content and now you are backtracking to say that it is "self-evident". Do you expect all readers to have access to the relevant Haynes manual?

  Could you please outline which GM europe engines used a centre-stud design with solid tappets? I am only aware of the 1965-1970 versions of the Opel CIH engine. And is there a source for which of these engines required the disposable feeler strip? 1292simon (talk) 23:11, 14 February 2020 (UTC)