Talk:Gear ratio

The article states "In the picture, each time the 13 teeth of the smaller gear make a revolution, 21 teeth of the larger gear make exactly one revolution." This statement is misleading or confusing. Each time 13 teeth of the smaller gear make a revolution, the larger gear has made 13/21 of a revolution.

It is not clear in this article which gear is applying power to the other. Can somebody clarify?

"Example" section
I accidently saved my edit before I meant to, so I didn't get to write a complete comment. I'll simply comment here, and be wordier about it!

The example section was incorrect about a few points and in places where it was correct, it was not a very good "example" (it was not representative of a realistic car). I've replaced it with a bit of an analysis of the gearing in a C5 Corvette Z06. I thought using an actual car would make the section more interesting.


 * It WAS based on an actual car; the Saab 96 - but you would be too young to know... MH 16:07, 11 December 2005 (UTC)

I think I've written up some pretty good information, but rereading it, it's really dry. It also needs wikification, and it uses all Imperial measurements. I'd like to fix this later, but if anyone gets to it first, please go at it! TomTheHand 18:33, 14 October 2005 (UTC)


 * Wikipedia should use metric/SI units by default! MH 16:07, 11 December 2005 (UTC)

Made an extremely minor change to the page.
A sentence was ended with a preposition.

What is reduction gear?
I searched reduction gear and it redirected me to this page. There is nothing that says reduction gear, only the word reduction appears once. There needs to be some sentence that says what a reduction gear does. This redirect was useless and uninformative.

Onionmon 21:35, 9 September 2007 (UTC)

please explain how to calculate the car speed if the following known datas 1.engine speed rpm 2.gear ratio 3.final redn ratio 4.circumfarance of the tyre —Preceding unsigned comment added by 85.154.4.246 (talk) 06:44, 15 April 2008 (UTC)

External links sections
I have added a link to an applet created by me that can calculate the theoretical speed at a certain rpm/gear. —Preceding unsigned comment added by Trident01 (talk • contribs) 23:49, 27 May 2008 (UTC)

Poor choice of teeth numbers
21/13 = 1.61538 which leads to 1:1.62

Then 1/1.62 gives 0.62 but it is really 0.6190

The risk is that someone will see 1: 1.62 and then see 1/1.62 or 0.62 as 1-1.62

25/13 would be better

25/13 1.923 and 1:1.923

Then 1/1.923 gives 0.52

Ircoha (talk) 17:16, 29 May 2008 (UTC)

torque multiplication
When we refer to torque multiplication in a manual transmission the affects of speed is what? —Preceding unsigned comment added by 65.191.108.82 (talk) 01:46, 1 March 2009 (UTC)

Suggestion for Clearer "Equations of Gear Ratios" Section
I don't think the article specifies what happens to torque on the output side of a gear. I think it is something like this but I'm just a novice and this is just a guess from information I have picked up from various web pages.

I have two gear cogs, A and B. A is my input gear, B is my output gear

R = Ratio of output B teeth over A gear teeth rpmA = RPM that A is spinning at rpmB = RPM that B is spinning at torqueA = Torque of A torqueB = Torque of B

rpmB = rpmA * (1.0 / R) torqueB = torqueA * R

In my own calculations for the 2004 Corvette (I also added my own data such as wheel size, transmission and differential losses etc., I can post that too if anyone wants it) I then get something like 400 Nm @ 1000 RPM in 4th gear at the engine and 1200 Nm @ 300 RPM at the wheels (Does this sound good?) so you basically "trade" RPM for torque via gearing. Anyway my point is, I just want the Wikipedia article to be best it can be, it would be nice if this article stated the torque equations clearly, which at the moment I don't think it does and I am definitely not qualified enough to research, verify and make this change. Hullo exclamation mark (talk) 11:36, 14 November 2009 (UTC)

Revisions to this article
I have rewritten the introduction and revised the general description section to try to provide a clear explanation of gear ratio. Hopefully, this helps clarify many of the questions that have appeared. Prof McCarthy (talk) 23:23, 27 July 2011 (UTC)

wth is this im in school and this is very hard dumb it down wth — Preceding unsigned comment added by 168.169.228.2 (talk) 17:17, 26 April 2013 (UTC)

Torque ratio given in this article was wrong. Correct one is given in : http://en.wikipedia.org/wiki/Gear_train

Merge with Gear train to Gear train and ratio?

 * Oppose I'm dubious about any merge that has to use a title name of "Topic 1 and topic 2".
 * The current article at gear train is poor, omits much of what it could and overlaps substantially (beyond what is essential) with gear ratio. However both of these articles could be remedied in place. I don't see the results of a merged article as being any improvement. Andy Dingley (talk) 18:09, 7 December 2013 (UTC)
 * oppose ↑ 46.253.36.123 (talk) 15:07, 1 April 2015 (UTC)


 * Agree Even if you remedy gear train it'll likely grow apart from gear ratio and the undesirable duplication will come back again. You can't talk much about one without the other. Fgnievinski (talk) 01:16, 8 December 2013 (UTC)


 * It may be worth considering including Epicyclic gearing and Differential (mechanical device) in this reorganization, because they are gear trains with gear ratios that are important to their use. Prof McCarthy (talk) 04:29, 9 December 2013 (UTC)

Sb23wiki (talk) 20:33, 13 September 2014 (UTC)I oppose merging the pages Because I think gear ratio is a different topic from gear train. — Preceding unsigned comment added by Sb23wiki (talk • contribs) 20:27, 13 September 2014 (UTC)


 * Agree Nearly all info on the Gear train article is also present in the Gear ratio. I do agree with Andy that it isn't a good idea to mention two topics in the title, just merge Gear train into Gear ratio, the latter already starts with the heading 'Gear trains with two gears', so if one were to be redirected from the former, the relevant data would still be easily accessible. Rmvandijk (talk) 11:07, 22 January 2015 (UTC)


 * Agree - topic would be better covered in gear train. — Preceding unsigned comment added by 74.38.77.101 (talk) 13:00, 2 August 2015 (UTC)