Talk:Horsepower

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Original horse power[edit]

The original horsepower unit was selected to show potential buyers of the new steam engines how much they would save by switching from horses to steam. The horsepower unit represented the rate of work a horse could do on a continous basis (all day long). Thats why its only a small fraction of the maximum capability of a horse.

Why is this entry flagged?[edit]

"This article or section may contain original research or unverified claims." How so?

Nominal horsepower[edit]

There is a sort-of-relevant discussion going on at Template_talk:Convert#Nominal_horsepower? - Globbet (talk) 21:27, 26 August 2011 (UTC)

If templates were smart enough to figure outthis sort of thing for themselves,we wouldn't need editors. Anyone remember User:Bobblewik? --Wtshymanski (talk) 17:52, 31 August 2011 (UTC)
That is pretty much in line with the conclusion reached there. I don't. Globbet (talk) 22:27, 31 August 2011 (UTC)

"Metric Horsepower"[edit]

There is no official measure of horsepower called "Metric Horsepower", only Americans call it this way. it is properly called "PS", and is based, obviously, on the German "Pferdestärke". This equals to ca. 0,735 kW, therefore 1PS = 1.36 kW (ca.). Also, the American Horsepower measurement (or is it the British one, I believe its called "SAE hp", and/or "bhp", which is 1.34 kW, is missing a detailed description here, how come?.--Daondo (talk) 22:36, 17 October 2011 (UTC)

Well, we've got a whole section titled "Metric Horsepower" which gives all these different metric horsepower units, ( those Europeans have different words for everything), and the rest of the article is talking mostly about 550 ft lbs/sec which is a British or Mechanical or SAE horsepower. You do know that SAE stands for Society of Automotive Engineers which isn't particularly British? --Wtshymanski (talk) 01:23, 18 October 2011 (UTC)
To make things more "interesting" in {{Infobox German Railway Vehicle}} and in {{DRG locomotives}} I found PSi which probably means indicated PS. One more conversion problem. Peter Horn User talk 20:43, 17 October 2012 (UTC)

Mechanical horsepower conversion procedure - numerical precision[edit]

From the standpoint of error propagation I found silly that the original 2 significant digits (1 hp ≡ 33,000 ft·lbf/min) expand through the conversion into SI units to final 17 significant digits (= 745.69987158227022 W). Ignoring the precision of the conversion factors themselves and assuming 1% relative error, the final conversion should be something like 1 hp≡ 33,000 ± 330 ft·lbf/min ≡ 745.70 ± 7.46 W. Even taking the original number defined by Watt as a number of 5 significant digits, this brings an error in the order of 0.00746 W (relative error of 10^-5) which renders the tail of digits into a meaning less nonsense. — Preceding unsigned comment added by 82.208.33.113 (talk) 22:55, 15 April 2012 (UTC)

(months later) Well, definitions are (by defninition) exact, so Watt's "33,000" has as many sig figs as you need. As long as we're talking about "definitions" of units and interconversions between them the precision is as high as ever needed. But it is absurd to give the final result to more significant figures than could ever be possibly resolved in an actual measurement. Anything more than 6 figures is going to make the reader's eyes glaze over and doesn't really improve the effect of the presentation. --Wtshymanski (talk) 13:36, 21 August 2012 (UTC)
The value used for the pound-mass has an erroneous extra digit. It should be .45359237 kg exactly, not .453592376 kg. And a full 5 digits of the final result, 745.699881448 W, are wrong. The exact value denigrated above, 745.69987158227022 W, is correct. Exact calculation in the definition of units avoids this sort of error. — Preceding unsigned comment added by 208.53.195.38 (talk) 14:15, 17 July 2013 (UTC)

Contradiction in bhp definition[edit]

At the top of the Measurement section it says bhp is "power delivered directly to and measured at the engine's crankshaft", and if you subtract "frictional losses in the transmission" you get shp. Later it says bhp is power before subtracting the auxiliaries such as alternator and hydraulic pumps.

So shouldn't that first section say something like this? "Brake / net / crankshaft horsepower (power delivered directly to and measured at the engine's crankshaft) minus frictional losses in the transmission (bearings, gears, oil drag, windage, etc.), minus auxiliaries such as alternators and pumps, equals Shaft horsepower." Kendall-K1 (talk) 16:48, 21 February 2013 (UTC)

Globalize?[edit]

Why is there a globalize template on the "Current definitions" section? Isn't horsepower a US unit? Kendall-K1 (talk) 02:15, 22 February 2013 (UTC)

Historical symbol[edit]

A ligature-style symbol/glyph/character \mathrm{H\!\!P} is used to denote 'horsepower units' in the book Aiba, S., A. E.Humphrey, and N. F.Millis, Biochemical Engineering. 1965, New York, U.S.A.: Academic Press. 333 pp.. (e.g. pages 167ff.). —DIV (138.194.12.224 (talk) 02:28, 22 March 2013 (UTC))

There is a unicode character ㏋ (U+33CB "square hp") but I can't find anything that says what it means or what it's used for. It's in the CJK compatibility block with other units of measure like mV, Hz, and gal, so it's probably horsepower. But it's not a ligature, it's two separate letters crammed into one glyph. Kendall-K1 (talk) 18:41, 4 April 2013 (UTC)

I welcome the article. My only comment is that I believe units of measurement named after those who helped define them have their first letter capitalized. (e.g. Watts, Amps, Joules, Faradays, Volts, etc.). If this is correct, the frequent reference to 'watts' should be corrected to 'Watts'. — Preceding unsigned comment added by 65.113.43.98 (talk) 22:39, 6 August 2013 (UTC)

use of funny f in the middle of units[edit]

There is a subscript f in the middle of many units that is undefined within this article, and its meaning is non-obvious. Feet? Force? Function? Can we define it the first time it is used? metaJohnG (talk) 02:22, 11 September 2014 (UTC)

Please, could you give us an example. I looked in the article and cannot find what you mean.-- Toddy1 (talk) 06:46, 11 September 2014 (UTC)
It stands for force -- i.e pound-force or kilogram-force. Pounds ARE a unit of force, but in lay usage pounds often denote mass (The amount of mass that experiences one pound of gravitational force at Earth's surface). Hence, people who are using pounds but also being precise about what they mean will use the terms pound-mass or pound-force. A kilogram-force is the force exerted by one kilogram of mass at Earth-standard gravity.

74.192.230.149 (talk) 21:47, 16 October 2014 (UTC)

About the history of the unit[edit]

The small change I've recently made is;

From:
This was rounded to an even 33,000 ft·lbf/min.[1] Watt calculated the power as 33,000 ft-lb per minute.[2]
To:
Watt defined and calculated the horsepower as 32,572 ft·lbf/min, which was rounded to 33,000 ft·lbf/min.[3]

Somebody can also change instances of ft·lbf/min to lbf·ft/min, as in N·m, where force comes first and distance follows. There are many quantities with long units but if the order of individual units in these combined units keep changing from article to article, it ends up being inconsistent, and thus potentially confusing.

An excerpt from the previously cited reference is given below:

In 1783, James Watt created the term of “horsepower” to describe the power of the new movers. Watt defined one horsepower as the amount of work required from a horse to pull 150 pounds out of a hole that was 220 feet deep. Watts calculated the kinetic energy as 33,000 ft-lb per minute. Two horses together produced over thirty hp.

Do not cite these kind of references for the love of solar system.

If you don't know the difference between work and power, do not edit a \\//ikipedia article called horsepower, and as a digression, I'd also strongly advice against writing an MS thesis, or a thesis for any other degree, that will be approved. 85.110.3.29 (talk) 10:51, 6 December 2014 (UTC)

  1. ^ Tully, Jim (September 2002). "Philadelphia Chapter Newsletter". American Society of Mechanical Engineers. Retrieved 2007-08-11. 
  2. ^ MEDLOCK, CHELSEA A. (2007). "Delayed Obsolescence: the Horse in European and American Warfare from the Crimean War to the Second World War". University of Kansas. pp. 5–6. Retrieved 9 June 2014. .
    This incidentally claims that "Two horses together produced over thirty hp", giving Horse: How the Horse has Shaped Civilizations, by J. Edward Chamberlin, pub BlueBridge, New York, 2006, p108 as a source for that claim. However, page 108 of that book makes no such statement.
  3. ^ Tully, Jim (September 2002). "Philadelphia Chapter Newsletter". American Society of Mechanical Engineers. Retrieved 2007-08-11. 
No we cannot change foot-pounds into "pound-foots". When people were using foot-pounds (and foot-tons), they expressed them as foot-pounds (and foot-tons). They did not express them us "pound-foots".
As for your edit, it is of no value. I have reverted it. Instead I have added another citation - to a source that is not behind a paywall, which can also serve as a citation for the statement that "Most observers familiar with horses and their capabilities estimate that Watt was either a bit optimistic or intended to underpromise and overdeliver; few horses can maintain that effort for long".
85.110.3.29 made quotation from "the previously cited reference" - which reference was he/she referring to?-- Toddy1 (talk) 12:14, 6 December 2014 (UTC)
The source for the statement "Two horses together produced over thirty hp" was a thesis/dissertation for an MA thesis Delayed Obsolescence: the Horse in European and American Warfare from the Crimean War to the Second World War, and appears on page 6. However the source cited by the MA thesis for that statement is a book that does not make the statement. The reason the footnote explains this, was that well-meaning people such as yourself kept putting it into the article, and they needed to be told why it was being deleted.-- Toddy1 (talk) 12:24, 6 December 2014 (UTC)
Gee, making people understand a simple, tiny thing can be quite costly indeed. Especially when they try real hard not let other editors improve the article.
Okay read what I write this time, and read carefully. You do not seem to understand what I'm writing (probabaly as clearly as possible).
You said "As for your edit, it is of no value. I have reverted it. Instead I have added another citation...". The statement to which you added an additional citation is not even what I changed. So basically, you don't see a value in something that is not even what I changed. I hope you can comprehend this. In fact your revert is of no value, because you have done it without even understanding what the edit was, and why it was made.
This is the version you (strangely) insist on keeping: "Watt calculated the power as 33,000 ft-lb per minute.[12]". But this is not what the referenced material (i.e. the 12th reference) says. Let me repeat, here is the relevant excerpt from the reference that is still cited in the article:
"In 1783, James Watt created the term of “horsepower” to describe the power of the new movers. Watt defined one horsepower as the amount of work required from a horse to pull 150 pounds out of a hole that was 220 feet deep. Watts calculated the kinetic energy as 33,000 ft-lb per minute. Two horses together produced over thirty hp."
As you can see (hopefully), it says "Watts calculated the kinetic energy as 33,000 ft-lb per minute.". Firstly, ft-lb per minute is not even kinetic energy, and this says how messed up that reference is. Secondly, you can not write a sentence and make a citation for it, which is non-existent. I hope you can comprehend what I'm saying (in fact repeating) this time. That reference does not say "Watt calculated the power as 33,000 ft-lb per minute.[12]".
Now here is the funny point that seems to be troubling you: Nothing I have written so far, either in the talk page or in the article, has got anything to do with the statement "Two horses together produced over thirty hp". That sentence is quite funny, just like the rest of the statements I wrote above from the same reference. Can you also comprehend that? I understand your english may not be well enough to comprehend fast but given enough time you can comprehend what I'm saying.


Okayy, as for the suggestion of re-writing the unit as lbf·ft/min:
The article that explains the unit is Pound-foot (torque). As you can see, the name of the \\//ikipedia article is pound-foot, which actually refers to poundforce-foot, i.e. lbf·ft. And in the article, it is stated that "... foot-pound (ft·lb or ft·lbf) is also sometimes used interchangeably with "pound-foot" to express torque.". So, as I wrote up there the first time, it is not necessarily wrong, but inconsistent, considering articles like torque. If there is a combined unit like lbf·ft/min, using it as ft·lbf/min in some articles and as lbf·ft/min in some articles is inconsistent. Try to be consistent, because consistency matters.
P0S: I said "somebody can edit...", I've been editing for the last five years, which is possibly longer than you, therefore don't rush to speak as "we" as apparently we (you and I) can very well disagree.
85.110.3.29 (talk) 13:12, 6 December 2014 (UTC)
You seem not to understand.
Horsepower is a measure of power. If you disagree with this, please say.
Power can be considered as energy per minute.
Foot-pounds and foot-tons are a measure of energy. (There is also a metric unit called a Joule that some people use for this.)
Therefore power can be expressed as foot-pounds (or foot-tons) per minute. (People who use metric units use Joules per second for this.)-- Toddy1 (talk) 13:28, 6 December 2014 (UTC)
Reference 12 in the article is Marshall, Brian. "How Horsepower Works". Retrieved 27 June 2012. As far as I can tell this reference does not contain the statement: "In 1783, James Watt created the term of “horsepower” to describe the power of the new movers. Watt defined one horsepower as the amount of work required from a horse to pull 150 pounds out of a hole that was 220 feet deep. Watts calculated the kinetic energy as 33,000 ft-lb per minute. Two horses together produced over thirty hp."-- Toddy1 (talk) 13:38, 6 December 2014 (UTC)


There are 1308 words (!) under this section uptil this post and you still don't know what you are talking about let alone making any progress in this redundant and ill-purposed discussion, which you can't seem to have enough of and which is not worthy of \\//ikipedia at all. Nothing I said so far got anything to do with the question of whether horsepower is a measure of power or not, which would (hopefully) be an unnecessary question. You are wasting your and others' time.
The field I work in is mechatronics, so I am supposed to have some idea about what I would say on horsepower, but the thing is I didn't even write anything new, I just combined two sentences and removed the problematic reference. But I have to tell that the article is still in pretty bad shape as it is.
Okayy, let me re-state (in fact repeat) the points you are missing for the third and the last time. Let's see if you can comprehend the items in the below list:
  1. First of all, what I wrote in the beginning of this section already lists the 12th reference. And secondly, of course it is not the 12th reference in the current version of the article because it is removed with my edit, which is the edit you reverted without having any clue about.
  2. This is the version you (strangely) insisted on keeping: "Watt calculated the power as 33,000 ft-lb per minute.[12]". But this is not what the referenced material (i.e. the 12th reference) says. Instead, it says: "Watts calculated the kinetic energy as 33,000 ft-lb per minute.". Firstly, the cited reference is a bad source of information because ft-lb per minute is not a unit of measure of kinetic energy but of power. And secondly, a \\//ikipedia article should not include a cited statement which does not exist in the cited material. Okay let me say it for the fourth time; That reference attached to the sentence you insist on reverting to does not have the string "Watt calculated the power as 33,000 ft-lb per minute.[12]" anywhere in it. So, do not insist on reverting to that version, it is wrong, you see? If you don't understand what I'm saying, get a help from one of your friends who understands English language better.
  3. Considering the name of the article Pound-foot (torque), it is more intuitive that force comes first and distance follows in the combined unit. The article torque also refers to lbf·ft and N·m, where again force comes first and distance follows, and it also states "This avoids ambiguity with mN, millinewtons.". So, repeating for the third time, ft·lb or ft·lbf is not necessarily wrong, which is also stated in the article Pound-foot (torque); "foot-pound (ft·lb or ft·lbf) is also sometimes used interchangeably with "pound-foot" to express torque". The thing is, consistency is an important aspect of scientific writing, and the version you insist on reverting to is "This was rounded to an even 33,000 ft·lbf/min. Watt calculated the power as 33,000 ft-lb per minute.", where two different notations of the same unit "ft·lbf/min" and "ft-lb per minute" are written side by side.
  4. I find it great that people from all over the world are the editors of this place, but you seem to have a problem in reading comprehension of English language and/or you seem to have a tendency to revert edits without understanding them. In either case, please refrain yourself from reverting the edits made to English \\//ikipedia by other editors, especially when they are reasoned well enough in the talk page of the article and you find it difficult to understand the text and/or want to revert it for no valid reason. None of us have so much time in our hands and this was far too long, far too inefficient. Note that these kind of actions frustrate editors and thus prohibit improvements in \\//ikipedia. I might also suggest that you'd better refrain yourself from editing the articles in English \\//ikipedia before taking others' opinions that your language is coherent and consistent enough, which would not be ambiguous for readers.
85.110.88.64 (talk) 16:12, 6 December 2014 (UTC)
Wikipedia has a policy of no personal attacks. In your last post you made a personal attack on me. Cut it out!
Relax, nobody made a personal attack on you, you misinterpret what you read because, as your profile says, you don't understand English. just refrain yourself from editing articles or other editor's edits in English \\//ikipedia until you get a better grasp of English, because it takes too much time to explain to you what the edits actually tell. Posting the "welcome to wikipedia" message in the talk page, and then the warning message against getting banned due to edit war was quite strange though I must say. There is no point in playing witty games. Many edits to \\//ikipedia are made in good faith. Although you insisted on reverting the tiny edit I made again and again without understanding it at all, the edit is still there. There was nothing to revert once you could understand it, because it fixed what was wrong about the article. It just took you so long to understand. This is a fact, not an attack.85.110.88.64 (talk) 22:26, 6 December 2014 (UTC)
Torque is not relevant here. I realise that torque is measured in foot-pounds. I did not know (before this conversation) that some books express this a pound-feet. One of the good things about Wikipedia is that you learn new things every day. I can see that there are advantages in expressing torque as pound-feet, because that makes it clearer than the measure is of torque and not energy (energy is also measured in foot-pounds).
Yes, torque is quite relevant here, in fact I already explained what its relevance was more than once. Just keep reading the contents of this section again and again, it'll sink in. Hint: Power is also torque times angular speed, and it isn't surprising at all that there is a (mechanical) power calculation in the torque article, so perhaps a good candidate for your favorite English word can be "consistency". Anyway, I'm glad you learned something with this discussion, because honestly I was so sure it turned out to be completely useless.85.110.88.64 (talk) 22:26, 6 December 2014 (UTC)
In the version before your edit, citation 12 was "Coon, Brett A. Handley, David M. Marshall, Craig (2012). Principles of engineering. Clifton Park, N.Y.: Delmar Cengage Learning. p. 202. ISBN 978-1-435-42836-2." Page 202 does not have the quotation ("Two horses together produced over thirty hp") you claim it does.-- Toddy1 (talk) 17:57, 6 December 2014 (UTC)
In this beginning of this section, my first post gives all the details of the reference I removed. Just read, it'll sink in. Very easy, just go to the beginning of this section, and read my first post slowly. Believe it or not, it'll tell you everything you want to know.85.110.88.64 (talk) 22:26, 6 December 2014 (UTC)