Talk:Automatic transmission

energy efficiency section = huge bogus?

There are no citations and the arguments are that there are whatever losses due to pumping and pressurizing the automatic and it is even argued that the human physical and mental power provided by gear shifting plays any considerable part. Now, anyone who has ever been in a manual and automatic car knows that 1. in manual you gear shift basically as little as possible because every time you do so it stops the entire engine transmission for the time it takes you to react, press the pedals and what not and you have to concentrate on hitting the gear correctly, 2. in a car with automatic you drive constantly on very low rpm, e.g. 2000 rpm, whereas in the same car, same engine, etc. with manual transmission you run every gear from maybe 3000 to 6000 rpm. You just cannot get anywhere near as low as the automatic can, because you just can't gear shift as often as it would be required to keep constant rpms and you can't hit the gears properly if gear shifting from very low rpm.
And that's really the main factor to energy efficiency: hitting the very optimal rpms of the engine all the time. I think that every single factor mentioned in the current section is marginal at best, if not even irrelevant or plainly wrong. Now there might be all sorts of different cars and types and engines and transmission systems, but from the ones I know that were build both as manuals and automatics, the automatics have effectively been far more fuel efficient (maybe 20-30%) opposed to reasonably driving with manual. Would be nice if someone who is more educated could correct that section. — Preceding unsigned comment added by 77.10.28.244 (talk) 07:13, 14 May 2013 (UTC) Oh, and btw. I am talking about actual cars on real roads run by real people. That means, considering real circumstances like city traffic, uphill, downhill, etc. Of course, if you run a car with manual at constant 90km/h in some wind tunnel in the highest gear it will beat the automatic, no question. But that's not very realistic, is it?

Well it depends on what type of automatic, but for the automatic described in the article, yeah, they are much less efficient. CVT and MMT/DSG-type automatics can be more efficient but they're horrible to drive unless you're driving smoothly on a flat road.

The Torque converter autos in the article are much nicer to drive but are always losing power because of the way torque converters work - To describe it in a way that's easy to visualize, imagine two fans, one spinning to 'blow' the oil against the other fan.

Obviously, the 'blowing' fan will always spin faster than the receiving fan - These are the pumping losses that are described.

In lower gears and under load, a manual will destroy a torque converter for fuel efficiency and power delivery - If you've ever tried to tow something heavy with an auto vs. a manual up a hill, you'd know this. That said, most modern torque converters 'lock' at higher gears so that both shafts spin at the same speed with no loss.

Citations are available all over the place - Just look at the mpg and CO2 figures for any manual vs torque converter auto (e.g. http://www.parkers.co.uk/cars/reviews/facts-and-figures/hyundai/i40/tourer-2011/running-costs/ since I was looking at it just now). The figures for the torque converter are usually much worse than for the manual; The only cases where they aren't are for CVT (Gutless (As in sod-all torque), high-revving under load, but can achieve high efficiency when driven gently) and MMT/DSG-type autos (Basically manual gearboxes with computer-controlled clutch and gear shifting) 77.101.174.194 (talk) 21:01, 18 June 2013 (UTC)

Overly technical

I just read this whole thing and I don't get how the transmission actually works, or how it can change from one gear to another. This article is overly technical.

Agree, I believe this page could use an overview section, as well as significantly more media (diagrams/photos) to make it easier to comprehend to the lay reader. Some of the other sections could also be organized better, see the [Differential (mechanical device)] page, for an example of what I have in mind. Rohanisaac (talk) 20:59, 5 October 2014 (UTC)

???

It might be worth working up something about Constantinesco's non-hydraulic torque converter of the 1920s. Unfortunately I don't have a link at the moment, but I seem to recall altavista finds it easier than google for some reason. PML.

I'm also pretty sure that some work with hydraulic torque converters began much earlier than the 50s. --Morven 06:48, 7 Oct 2003 (UTC)

Googling for "Constantinesco torque converter" seems to find a few references. --Morven 06:50, 7 Oct 2003 (UTC)

I think the place to look might be [1] - "fluid" because he also looked into power transmission in fluids by means of energy pulses. PML

Gear selection / Shifter

This was completed on January 5 2007 KG

It would be useful to include a section on the shifter mechanism found in automobiles with an automatic transmission. This comes to mind as I work on D (disambiguation) and encounter "D for Drive". I know of three main types: push-button, floor shifter (illustrated in this article) and steering column shifter. Questions that come to mind are a) are there any other styles? and b) is "D for Drive" the same across all languages, or might it be (looking at Wiktionary) "F for Fahren" in German or "V for Vehar" in Ido (though I'd be verrry surprised to see a gear selector encoded for Ido :) ). Thanks for thinking on this and perhaps editing it in. Regards, Courtland 02:13, 29 September 2005 (UTC)

I think the symbols for the transmissions have been standardized, so every carmaker is allowed to use the same letters in the same order. On another note, the BMW and Mercedes's shifter "stalk" is worth mentioning as well. 220.133.92.72 (talk) 20:04, 1 September 2008 (UTC)

Some cars, e.g., the early (1961) Pontiac Tempest, had the transmission selector on the dashboard, next to the ignition switch and radio (IIRC). There were only four choices: R, N, D, and L (i.e., no P). 71.131.218.173 01:04, 20 July 2006 (UTC)

The gear Automatic Transmission Modes section was very confusing, and really could stand to be reformatted. Vendor specific information really should be below general information, for example the information about Honda and Acura models appears ABOVE the more traditional idicators in generic form. I've moved the section about vender specific modes to the bottom, and made minor changes to the overdrive, drive, and "2" entries for clarification. Jo7hs2 03:20, 28 October 2007 (UTC)

Honda automatic

Did you know that all Honda automatics are actually hydraulically operated manual transmissions with torque convertors in place of the clutch? The transmissions of the Chapparral race cars of the 1960's, such as the famous Chapparral 2J 'Fan Car', were similar as they used a torque convertor instead of a clutch, however the synchro-less 4-speed gearbox was manually shifted.

I find this incredibly doubtful, to say the least. While I'm not certain on the operations of the Chaparral gearboxes (I've heard that they were everything from simply a built-up manual valvebody TH400 to being a dog-box with a torque converter), the idea that Honda automatics are really hydraulically operated manuals (instead of planetary-gear / clutch-pack equipped automatics) is far-fetched at best. Hydraulically operated manuals have not even been in racing use for a terribly long time, and only a handful of cars on the street use them (any Ferrari with the 'F1' designation, or the recent BMWs with the SMG transmission) as their cost is very high compared to a normal automatic. Ayocee 14:57, 6 February 2006 (UTC)

I once possessed one of those Honda Civic semi-automatic transmission called Honda-Matic. Mine had 3 speed, 1st, 2nd, and O/D gear, alongside standard automatic transmission gear selection (P, R, N). Earlier models had only the 1st and 2nd gear. And you cannot compare Ferrari and recent BMW's to earlier cheapier Honda Civic transmissions, that's not hte same technology, and performance. Honda semi-automatic still fonction with planetary gearbox (being manually controlled doesn't mean that it should be built like a manual transmission), only that it is the driver that controls bands and clutches to achieve gear change. They should not cost more than a regular automatic transmission, and at the best they are maybe easier to build. In place on the throttle valve cable, it is the shift cable that changes gears and actuate the bands and clutches to achieve that.Warhammer38m 04:58, 28 April 2007 (UTC)

My friend has an old Civic (70s era) and it has a automatic gear selector on the floor, but instead of a "D" it goes P N R OD 2 1. You simply go up as you drive. —Preceding unsigned comment added by 24.129.234.97 (talk) 04:56, 29 June 2010 (UTC)

Honda used an automatically-shifted manual for several years in the 1970s & 1980s; I was doing comparison studies on them whilst an R&D engineer for General Motors. The efficiency of these ran about 1 to 2 percent less than a TH400, most likely due to pumping losses.ziggaroo 13:44, 30 December 2010 (UTC)

Japanese "Kei" cars

Some Japanese "kei" cars (yellow license plate, with a 650cc engine for reduced tax) have a bizarre combination auto gear box. Two fixed ratio low gears, and then a CVT gear above for regular driving. Confirmed in the Suzuki WagonR, and Daihatsu Move, and not in the Subaru Vivio. Unfortunately, I don't know enough about how they work to put an entry in the article, and it'll be difficult to find an english speaking engineer to explain. Given how underpowered these engines are (I estimate under 50bhp), it's probably an attempt to eke out a little more power, and it certaintly seems to help for going up mountains.

PSA AL-4

There is no mention of the AL-4 gear, in the models list. This gear is used by all/many of the recent models of French cars Peugeot, Renault, Citroen . Can you add a link to it, and a list of cars where it is used. It has had many reliability problems. —The preceding unsigned comment was added by 89.0.228.55 (talk • contribs) .

Were not Mercedes (rather than BMW) the first to offer a five speed automatic transmission? If I remember correctly it was available in their 1989 SL?

Failure causes?

What are the actual failure modes for an automotive tranny? For example, a worn/slipping clutch plate will cause the torque converter to not couple properly, leading to power loss at hill climbing and/or highway speeds. This leads to the build up a lot of turbulence in the torque converter, which results in a lot of heat being dumped into the tranny. Now, every consumer brochure states that heat kills trannies, but how is it doing this? Is the high heat warping the valve body or something? Are some bearings getting blown out because hot tranny fluid can't protect them any longer ?  ??? linas 17:48, 22 May 2007 (UTC)

On steering wheel

By the way, what do you call a gearshift on the steering pad, instead of off of it. --PJ Pete

Marketing lingo right now seems to label them as "paddle shifters" when they are on the sides of the steering wheel. The handful of vehicles (mostly modified cars) that have shift mechanisms directly IN the steering wheel are generally just called shift buttons, or something like that. If my assumption that "steering pad" means the surface of the steering wheel... Jo7hs2 03:23, 28 October 2007 (UTC)

Foot brake

The article sais: "In some cars (notably those sold in the US), the driver must have the footbrake depressed before the transmission can be taken out of park." Shouldn't it say pressed?Alessandro Malfatti (talk) 00:44, 7 May 2008 (UTC)

No. "Depress" doesn't mean "don't press" but rather "push or pull (something) down into a lower position : depress the lever" -- or in this case, the pedal. --Fletcher (talk) 00:58, 7 May 2008 (UTC)

To avoid that ambiguity, I'm going to change it to "applied". Atlant (talk) 16:16, 7 May 2008 (UTC)

I don't think there is any ambiguity -- it is a common English word -- but I'm not going to object.--Fletcher (talk) 16:59, 7 May 2008 (UTC)

Depressed

The problem with "depress" and "depressed" is that the word has an unrelated meaning suffering from extreme sadness, a form of mental illness. 76.21.8.213 (talk) 02:08, 18 June 2008 (UTC)

Don't be silly. Fletcher (talk) 02:23, 18 June 2008 (UTC)

You can't shift from Park until you yell at your footbrake for a few minutes: Because shifting from Park requires the footbrake to be "depressed". —Preceding unsigned comment added by 24.129.234.97 (talk) 05:27, 29 June 2010 (UTC)

{{copyedit}} tag

Can you please explain what exactly still needs copyediting? I don't really see it. Arienh4^(Talk) 12:58, 12 June 2008 (UTC)

The edit summary that I gave when I added the tag attempts to give a clue.[2] There are many unnecessary parenthetical remarks (poor and/or lazy style) and an amazing plethora of this/that pairs joined with a slash, which is also very bad style. I started to edit the article, but I do not have enough technical knowledge of the subject to know how to properly interpret and convey the subject matter. That in itself is indicative that the article is somehow lacking. If it was very well written, I should come away with a fuller understanding than I do currently.

There are limited legitimate uses for parentheses in well composed prose, and joining terms with a slash is simply not necessary in good writing.

An example:

In order to select gears/modes the driver must push a button in (called the shift lock button) or pull the handle (only on column mounted shifters) out.

Ugh! For starters, I do not know in this technical context whether gears and modes are the same thing or different but related things. That's not my fault, rather it is an example of the article failing to explain itself clearly and fully. Neither of those two parenthetical remarks are needed, and certainly not both in one poor overloaded sentence. Either leave them out completely as not necessary to understanding the core concepts, or rewrite the whole bit, perhaps as multiple sentences. That's just one example. The article is full of similar writing defects.

I understand that often deep understanding of a technical subject and excellent writing skills are disjoint. I see it all the time in the technical field that I work in. It's not a case of being a grease-covered gear-head who just squeaked by in English composition. Because the writer has such a deep and detailed knowledge of the subject it can be very challenging to organize and present that knowledge properly, even if he has good writing skills. Choosing what details to include and what to omit, for example, can be very difficult. But it's important to omit much because the subject would otherwise fill a textbook. What remains is a can be difficult to present clearly to a reader not already steeped in the subject.

I briefly looked to see if there was a different tag that suggests more accurately what kind of attention the article needs, but I didn't see one. And, yes, my parenthetical remarks and slashed/stroked terms here are intentionally poking a little bit of fun at my pedantry on the subject. ;) --Kbh3^rdtalk 16:35, 13 June 2008 (UTC)

I've just gone over the entire article; fixing gramatical errors, and also adding some better technical details/terms/descriptions. Maybe the {{copyedit}} banner can now be removed. 78.32.143.113 (talk) 11:30, 13 January 2010 (UTC)

How it works...?

In the article, is there actually a section on how the automatic transmission actually works? Or is the link at the bottom to HowStuffWorks the closest it gets? Nonagonal Spider (talk) 07:30, 29 August 2008 (UTC)

Please explain the Bang mode

I don't understandand the following. Is it a bad english, bad joke or is it me? Thanks

Bang (B or I)- This allows the car to unlock and turn the sensors on some cars to allow if the drive is not engaging properly. This is used for cars that have to be careful from speeding alot of times. This is used only for the summer and fall. —Preceding unsigned comment added by Drevokocur (talk • contribs) 11:02, 8 September 2008 (UTC)

DSG-type transmissions

Volkswagen Group, Mitsubishi, BMW and others using this type of transmission (pioneered commercially on the Veyron) are NOT an automatic transmission even though they will shift under the control of a computer as they have no torque converter. They have a proper clutch, it is electronically-actuated. So really they are a computer-controlled manual transmission are they not?

There are at least two specific articles for 'DSG-types'. One is the generic dual clutch transmission (DCTs) which gives an overview and lists all DTCs from all transmission manufactures and applications. The other notable article is the Direct-Shift Gearbox - the specific Volkswagen Group DSG transmission. Oh, and these types were not 'pioneered' on the Veyron at all - they were actually pioneered on the Volkswagen Golf Mk4 R32 in 2003. ;-) 78.32.143.113 (talk) 09:31, 13 January 2010 (UTC)

Moreover the Veyron 'box was farmed out to Ricardo as, allegedly, Borg-Warner couldn't build one capable of handling the torque (a mate worked on it). Mr Larrington (talk) 12:43, 19 August 2010 (UTC)

Automatic transmission for people used to manual transmissions

After learning on and driving manual transmission for many I have trouble getting used to a torque converter automatic. Part of it comes from driving short distance with cold engine and transmission. But what I really do not understand is torque lock up. For example when accelerating after a traffic light:

• I open the throttle until I feel the torque gets to much for the tires. The engine revs much to high and here in Germany everybody thinks I am doin' it wrong to the clutch.
• At 2500 RPM I close the throttle as much as idle regulation allows me to and with a little luck the transmission switches into second gear with a slight forward jerk. Sometimes the automatic is too slow and produces a backwards jerk.
• Now I open the throttle until I feel the ECU starts to richen the fuel.
• At 3000 RPM I close the throttle. And when I open it again sometimes I end up in second gear with torque converter lock up. This is quite nice, but how do I reliably select between second gear with lock up and third gear with torque converter? I guess it can be steered by the duration I close the throttle.

In case I cruise with lock up and then kick down, how does switching gears work internally? I guess it is like:

• open breaks disks of the old gear under full torque.
• let the engine rev up.
• when the engine RPM is right for the lower gear, release lock up and engage break disks of the new gear under almost no torque.
• after additional 1000 RPM full engine torque hits the break disks.

This should give a backwards jerk, which is indeed the case, but it is almost unnoticeable, thus I am unsure. Should I avoid kick down, since it means opening break discs under full engine load? My engine has relative low torque and the ECU cannot close throttle at switches automatically. Anyways kick down is so much faster than down-shifting on a manual transmission.

Above 3500 RPM my torque converter looses efficiency and is locked up and only used as a visco-clutch while closing break disks to avoid overheating of the disks, though I never tried running into RPM redline.

The delay if switching from N or P to D or R is due to the silly sequential gear knob? Why does the automatic not use an H with N in the middle?

How much energy is needed for the oil pump (compared to the engine oil pump)? How much energy is lost due to break disk and lock up slippage? The torque converter is not efficient in coupling mode, therefore it is then locked up. Coupling mode is a typical condition in driving in a lot of driving situations and not only at low power cruising and thus an integral part of the driving experience on a high quality torque converter transmission. The driver avoids the region between torque converter acceleration mode and lock up by dictating clear transitions using the throttle, much like the gear switch.

I hope some of you with more knowledge can include an automatic for manual-guys section into the article! A CVT is much more automatic transmission. A DSG is a much more efficient transmission.

Arnero (talk) 09:37, 23 March 2009 (UTC)

relax bro, it's an automatic. here's how you drive it: to go you push on the gas. to stop, you push on the break. hope this helps 67.180.178.60 (talk) 00:21, 17 May 2009 (UTC)

Lol I agree with the guy above. Relax, it's automatic, don't worry about the little stuff and let the car do the work. Just shift into drive and get where you want to go. Just press the gas, no other techniques required. If you don't like not being in control then stick to driving stick. —Preceding unsigned comment added by 24.129.234.97 (talk) 05:32, 29 June 2010 (UTC)

Just to clear things up. In an automatic transmission the more you step on the accelerator, the faster you accelerate. If it is a CVT (continuously variable transmission) the engine will work at the same RPM, but your speed will increase. On a ranged-gear gearbox you will feel the jolt you describe as the 'box changes the gears. Also, the engine will fade and then accelerate again (much like driving a manual). Now, if you're worried people at stoplights are mocking your clutch control, you have two options:

1. Don't floor the accelerator, or
2. Get a manual

In any case, flooring the accelerator from standstill is not recommended. The best way is to start pressing it slowly at first, and increase the speed at which you are pressing it further down as the car pulls off

The downshifting, by the way, has nothing to do with what you describe. In a ranged-gear gearbox the downshift occurs when the speed is low enough for the downshift (that's a major drawback of automatic transmissions, as you cannot use downshift to slow down, and when climbing steep slopes you have to wait until the speed decreases, instead of overreving the engine and maintaining higher speeds). In a CVT the drive ratio is changed smoothly, so that the engine is always in its efficient range. In both cases this is achieved by means of something much like a centrifugal governor. Please, no discussion about the centrifugal force being real or imaginary, I've had that one in another article

lasombra bg (talk) 19:57, 9 March 2011 (UTC)

Lexus IS-F tranny photo

I think the picture of the Lexus IS-F's tranny at the top of the article should be removed due to it not being an automatic at all. It is a semi-automatic. —Preceding unsigned comment added by 70.24.181.11 (talk) 00:02, 3 April 2009 (UTC)

DSG/manual controls for automatic transmission

"Since these gearboxes also have a throttle kickdown switch, it is impossible to fully exploit the engine power at low to medium engine speeds[dubious – discuss][citation needed]."

I left this paragraph there. I also added somewhere the fact about the fly-wheel clutch in automatic transmission (that the engine does not slow down the car when the driver steps of the throttle) and thus more nervous usage of the brakes in cars with automatic transmission.

When DSG first came out I really liked the concept. Then I tried it and testdrove a Golf GTI. I selected manual mode and I accelerated in the first gear with full throttle (like I always do). At around 3000RPM I tried to shift to the second gear but was ignored (because of the kickdown switch) -- I thought that I had made a mistake. Later when driving in the third gear I again used full throttle and the engine downshifted by itself. Thus this gearbox was out of the question for me.

Thus, if the driver cannot use full throttle without the engine either downshifting or ignoring an upshift command, how can the driver exploit all the available power at low to medium RPM?

I know, I could still use full throttle, if I somehow could avoid triggering the kickdown switch. But I'm unable to do so and also quite unwilling to learn to do so. This is an unnecessary problem caused by sick engineering.

I also thought about this in normal Automatic (not DSG). The engineering problem is to map a given pedal input (at a given speed) to a gear and throttle. Since lenght of pedal way in an automatic is not longer than in a manual, one would expect a stronger sensitivity of the pedal in an automatic, since in order to map all available gears for a given speed (which may be at least 3) an automatic would have to map the range of idle until full throttle at least 3 times to the available pedal way. Also there is the requirement, that given a very small difference in pedal input which may cause a downshift but which should not cause a different acceleration. Thus by this requirement alone, an automatic prevents one from using every available gears (for a given speed) together with every possible throttle input.

In general: I have the impression, that with an automatic one is unable to exploit the power of the engine at low to medium RPM. Since there is nobody testing this (by e.g. measuring acceleration from 0..100km/h with the limit of max. 3000 or 4000 RPM) I can only say this is an impression. But I think an automatic kind of trains the driver to avoid full throttle -- and people in the US a very well "trained by there cars". Also the sedated way of driving in the US

(nobody uses full throttle, nobody shows off with high acceleration at speeds higher than 30mil/h, people simply block the highway at any speed even lower than the speed limit)

and the competitional way of driving in Germany

(people actually are forced by law to yield the left lane, if somebody wants to pass. This also and especially includes driving on uphill roads.)

and the difference in ratio of automatic to manual between US and Germany proves my point indirectly. —Preceding unsigned comment added by ExcessPhase (talk • contribs) 05:41, 13 June 2010 (UTC)

Article lay-out

After discussing a possible edit at Epicyclic gearing (see Talk:Epicyclic_gearing#Switching_gears_by_use_of_pinions ) and coming to the conclusion that the info of that particular edit didn't belong there, it seems that instead, this article needs a cleanup for clarity.

In general, the headlines presently go as follows:

• 2 Automatic transmission modes
• 3 Hydraulic automatic transmissions
• 3.1 Parts and operation
• 3.2 Energy efficiency
• 3.3 History and improvements
• 4 Automatic transmission models
• 5 Continuously variable transmissions

6 Manually controlled automatic transmissions

For clarity, I propose this arrangement:

• 3 Transmissions with epicyclic gearboxes
• 3.1 Automatic transmission models --> change to "Epycyclic gearbox types"
• 3.2 Automatic transmission modes --> change to "Gear range"
• 3.3 Parts and operation
• 3.4 Energy efficiency
• 3.5 History and improvements
• 4 Transmissions with continuously variable transmission gearboxes
• 5 Manually controlled automatic transmissions --> change to "Control of gear switching"

Allot of confusing things of the text are taken out with this setup, ie manual control for example is not possible in CVT's, so having a level one headline for this makes the whole confusing, ...

Finally, add the references from the old edit as noted at Talk:Epicyclic_gearing#Switching_gears_by_use_of_pinions, and add a much needed image (showing fluid coupling + planetary gearbox 91.182.7.40 (talk) 10:37, 15 December 2010 (UTC)

I'm wondering whether the Adjustable-speed_drive also should be mentioned. This can be done by adding

• 5 Transmissions with Adjustable-speed_drive gearboxes and changing the current 5 to 6

91.182.29.99 (talk) 14:50, 18 December 2010 (UTC)

Compression Braking vs. Vacuum Braking

The section on 'Brake (B)' mode seems to imply that all non-hybrid engines use compression braking. Petrol engines use vacuum breaking - compression braking is found on diesel engines due to their lack of a throttle butterfly to create the vacuum. The unspecified Toyotas that have this mode may all be diesel, but I think it gives an inaccurate impression. 'Engine Braking' on it's own would be an improvement, as this covers both modes. — Preceding unsigned comment added by Trippy72 (talk • contribs) 06:51, 16 November 2012 (UTC)

Disambiguation?

I don't know what things like in your respective regions/countries/space-time-coordinates, but here the term 'automatic transmission' is very ambiguous and doesn't necessarily refer to just torque converters.

In fact, torque converters are becoming increasingly rare in new vehicles here due to high CO2 tax penalties, and are giving way to CVT and MMT/DSG-type gearboxes which are generally included in the term 'automatic transmission'.

IMHO, this article should be a stub; Maybe give a summary of the broad meaning of 'automatic transmission', and then give a list of different types of autobox with links to specific articles (e.g. Torque Converter, CVT, and whatever the heck the correct term for MMT and DSG-type autoboxes are (Computer controlled clutch? Elecontrically actuated clutch and gears??))

What ya think? 77.101.174.194 (talk) 21:13, 18 June 2013 (UTC)

1. REDIRECT [[

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