Talk:Automated manual transmission

Manumatic

Quote:

Despite superficial similarity, clutchless manual transmission differ significantly in internal operation and driver's 'feel' from manumatics, which are automatic transmissions (using torque converter instead of clutch to manage the link between the transmission and the wheels) with ability to signal shifts manually.

I disagree with this statement. Manumatic is an obsolete form of semi-automatic transmission and does not have a torque converter. Biscuittin (talk) 20:49, 11 January 2008 (UTC)

Whether you disagree or not, the term is often used by the automotive press to describe a torque-converter-based automatic transmission with selectable manual upshifting and downshifting, in the model of Porsche's Tiptronic. Examples are found here[1], here[2], here[3], here[4], here[5], here (in hyphenated form)[6], and here[7]. That, if you're keeping score, is a selection from all four of the major US automotive printed magazines, plus the highly-respected Inside Line from Edmunds.com and the start-up Winding Road online magazine. That's a broad consensus among industry-watchers. Sacxpert (talk) 07:02, 5 July 2008 (UTC)

Semi-automatic operation

The article does not fully describe exact details of its operation. 1. What happens when a car with a semi-automatic transmission brakes to a stop when the transmission is in manual mode (i.e., the driver is expected to upshift and downshift)? Will the car stall if the driver does not shift to neutral? Similarly, will the engine lug/stall if the driver keeps it in too high a gear for a particular speed? 2. While upshifting or downshifting, does the driver keep the accelerator pedal depressed like automatic transmissions? In that case, does engine control take care of controlling fuel injection during the time window the clutch is being hydraulically engaged (so that engine does not rev high under no load or partial load)? —Preceding unsigned comment added by 66.65.27.201 (talk) 02:07, 4 November 2010 (UTC)

Auto/Automated Manual transmission.

Does this article refer a type of automated manual transmission, with an electronically actuated, hydraulic clutch, controlled by computers and a servomechanism? The clutch is basically hydraulically or mechanically/electronically actuated, making it automated, but the driver can still take manual control of gear selection if needed to, hence the term "automated." I realize the term "semi-automatic" may also be used to refer to a similar purpose, since "-semi" from Latin means "half," and since these transmission do have automatically actuated clutches rather than a manual clutch pedal, I guess it sort makes sense, and some of these transmissions can operate in a fully automatic mode, I guess that's hence where the term "-semi" (automatic) comes from. Since these have electronic or hydraulic mechanical clutches rather than manual ones, it sort of makes sense. Would Automated manual (AMT) be correct to use in this context? It does refer to a standard manual transmission, just with an electronic or hydraulic actuated, automatic clutch, rather than a manual one, hence everything is "automated" rather than fully "automatic." (Davism0703 (talk) 19:30, 24 February 2020 (UTC))

Please be aware that the term "automated manual" is under discussion at Talk:Semi-automatic_transmission#Automated manual.  Stepho  talk  22:46, 24 February 2020 (UTC)

Proposed article renaming

Hi folks. I hereby propose to rename this article "Automated manual transmission". The reasons for this is that there are other actuation methods for these gearboxes than electrohydraulic (such as vacuum, electromechanical and pneumatic) that should also be included in the article. Also, the term "automated" is much easier for the average reader to understand than "electrohydraulic", so it will allow people to easier understand the topic of the article. Cheers, 1292simon (talk) 08:35, 29 July 2020 (UTC)

Hey Simon, I fully support the article's name change. "Electrohydraulic" is complex, and kind of vague term, since not all these transmissions do use hydraulic actuation for the clutch and shifting, and since we learned from Johannes Maximilian, modern standard manual transmissions all already to use hydraulics and some electronics for the clutch, so that was quite intriguing to know. I totally agree with you on those points, since the average reader won't understand the term "electrohydraulic" very well. "Automated" is a much more friendly and easy-to-understand term. I look forward to this article being fixed, and thank you for all your editing and contribution efforts! Regards, Davism0703 (talk) 21:43, 29 July 2020 (UTC)

Hello Davism0703 1292simon, as I have promised, I have taken a look at my book: Harald Naunheimer, Bernd Bertsche, Gisbert Lechner: Fahrzeuggetriebe – Grundlagen, Auswahl, Auslegung und Konstruktion, 2nd edition, Springer, Berlin/Heidelberg/New York 2007, ISBN 978-3-540-30625-2. On page 154, all "transmissions" are explained in a table. The four main functions are divided into "enabling the vehicle's starting", "changing rotational speed", "how the torque is transmitted within the (gear)box", and "how the transmission is operated" (the German words used are very bizarre and don't allow meaningful translations without being a bit creative). Each of these four "basic functions" has several different "options", in total, there are five options each. So in theory, there are 4×5=20 possible transmissions for motor vehicles. Now not all of these 20 options are reasonable, which is why there is also a list of common car transmissions on page 164:

• Manual transmission (MT)
• Automated manual transmission (AMT)
• Non-variable automatic transmissions
  • Dual-clutch transmission (DCT)
  • Conventional hydrodynamic torque converter and planetary gearbox
  • Automatic intermediate transmission
• Hybrid drive (electric motor + electric generator driven by internal combustion engine)
• Mechanical continious variable transmission (CVT)

On page 191, there is a list of typical transmissions for lorries:

• Constant mesh gearbox without synchromesh and manual clutch
• Constant mesh gearbox with synchromesh and manual clutch
• Automated constant mesh gearbox without synchromesh with automated clutch
• Constant mesh gearbox with hydrodynamic torque converter
• Planetary gearbox with hydrodynamic torque converter

So I think we should stick to these common descriptions of gearboxes; an "electrohydraulic manual transmission" would be an "automated manual transmission". Best regards, --Johannes (Talk) (Contribs) (Articles) 10:03, 3 August 2020 (UTC)

Hi Johannes Maximilian, many thanks for doing this research to help us out. I'm really thankful that you're around to translate the bizarre German words for us! That makes sense to me about sticking to the common descriptions, and therefore "electrohydraulic manual" gets grouped under "automated manual". I find it interesting that the book lists hybrid drive as a type of transmission, I'd have thought that hybrid means the presence of multiple power sources in a vehicle, rather than being a transmission type in itself. Also, just curious, can you enlighten me about what an "Automatic intermediate transmission" is please? Thanks again for your help with this. Cheers, 1292simon (talk) 08:39, 4 August 2020 (UTC)

I have listed most of the important information already back in early August, but since Davism0703 has reached out to me once again, I decided to have another look at the book. The inital question was „should we move this article to "automated manual transmission"“, which I think could be well-answered using the information from the "gearbox book". Chapter 6.6.2 is dedicated to AMTs. On page 170 the book reads that in the beginning of automated manual transmissions, there were partially automated transmissions, that had two functions: engaging the clutch / taking off, and switching gears. These partially automated transmissions did only one of these automatically, usually the "engaging clutch / taking off". The 1967 VW WSK (Wandlerschaltkupplungsgetriebe, "hydrodynamic torque converter shift/clutch gearbox") was one of the first gearboxes of this kind, which had an automatic, mechanical clutch and a hydrodynamic torque converter; shifting gears was done manually by the driver. The automatic mechanical clutch enabled the "taking off" function, whereas the hydrodynamic torque converter enabled "taking off in any gear", it dampened the engine vibrations, and it provided torque multiplication, functioning as some sort of "reduction gearbox", so the actual mechanical gearbox only needed three forward gears (maybe you have wondered why "traditional" automatic transmissions with hydrodynamic torque converters usually have less gears than manual gearboxes – this is why). In the WSK, there was no "first" gear, instead, the first gear was converted into a reverse gear, the second gear was labelled first, the third second, and the fourth third. Now the VW WSK was unsuccessful, since it wasted a huge amount of energy; torque and energy are NOT the same, however, they both come in the SI base units kg·m²/s², which is why they can be converted into each other using angular velocity – but I don't want to overcomplicate things: Basically, the VW WSK's hydrodynamic torque converter converted most of the engine's torque into heat energy instead of sending torque to the gearbox and ultimately to the car's wheels. This was due to a lack of a lockup clutch: in "modern" (anything 1980s or later) automatic transmissions, the torque converter has a lockup clutch so the engine torque can go directly into the gearbox instead of having to go the wasteful way through the torque converter. And I guess you can imagine what happens if a lazy driver discovers that taking off in third is possible – he won't shift anymore, instead, he will let the torque converter do all the "shifting". So cars equipped with the WSK had a ridiculously high fuel consumption that was unacceptable even by 1960s standards (a regular 25 PS VW Standard, 1200 cm³ burnt around 10.4 litres per 100 kilometres). VW's WSK was unsuccessful, and virtually any other manufacturer's WSK was as well.

Starting in the late 1990s, transmission makers introduced what we now call the Automated Manual Transmission (AMT) – these also have the WSK's functions, with two exceptions: They can do everything fully automatically, and they don't have a hydrodynamic torque converter. The shifiting signal comes from either a Transmission Control Unit (TCU), the shift knob, or shift paddles mounted behind the steering wheel. These AMTs combine the high efficiency of manual transmissions with the shifting easiness of automatic transmissions. Their biggest disadvantage is the poor shifting comfort, because shifting requires a disruption in torque transmission from the engine to the wheels, which is easily noticable as "jolting". Some transmission makers have tried solving this issue by using oversize synchroniser rings and not fully opening the clutch during shifting – now in theory, this works, but as of 2007, there have not been any series production cars with such functions. In passenger cars, modern AMTs usually have at least six gears and a rather large spreading. In combination with a smart shifting programme, this can siginificantly reduce fuel consumption. In general, there are two types of AMTs: Integrated AMTs, and add-on AMTs. Integrated AMTs were designed to be AMTs, whereas an add-on AMT is a conversion of a regular manual gearbox into an AMT.

(Some anecdote: Back when I was a fireman, we had three engines: an MAN L 14.255, a Mercedes-Benz Axor 1824, and an Unimog 435.115. The Axor had an integrated AMT, the Unimog had an 8-speed-manual (a regular H-shifter with 8 gears on it), and the MAN had an add-on AMT. The shifting process in the MAN was hilarious with ridiculous jolting. This is just my personal guess, but I think that add-on AMTs would be unsuitable for passenger cars, simply because their shifting comfort is so bad. In fire engines however, an automatic gearbox can make driving for the machinist a lot easier, and fire engines need to be robust, reliable, and cheap; a poor automatic transmission is acceptable as long as it is inexpensive; but this is just my guess.)

Add-on AMTs can also function as a regular manual gearbox (with a manual shift lever), whereas integrated AMTs don't need a "normal" shift layout, so they can be designed with an optimised AMT shifting layout (which would be weird to shift manually). Integrated AMTs either have gear-selector drums (which only allows serial shifting and no gear-skipping, but this system is fairly inexpensive, because it needs only one actuator), or single actuators. Single actuator systems require one actuator for each shifting sleeve (which is why this type of system is more expensive, but it also shifts faster). The actuators can either be electro-hydraulic (more expensive, but faster, well-suited for singel-actuator systems, and allow for higher torque), or electro-mechanical (less expensive, but usually limited to 250 N·m of gearbox input torque, because the clutch actuation force increases with higher torque, and short shifting times; electro-mechanical actuators are basically just electric motors – using bigger motors reduces the motor dynamics due to the motors' higher mass moment of interia (which is not good for fast shifting), and bigger motors also put more stress on the car's 12 Volt electrical system; so you either have slow shifting and a huge lead-acid battery (not suitable for cars), or fast shifting and a not so big battery (works up to 250 N·m of torque)).

Now as I have stated, integrated AMTs don't need to be "H shifter friendly", so designing a three-speed gearbox with an additional reduction gearbox is easily possible. This reduces the gearbox size, and only has one disadvantage: When shifiting from "third" into "fourh", the gearbox has to shift from "third" into "first", and in addition to that, the reduction gearbox has to shift from "low" into "high" (so two shifting processes are required). Another possible design is putting all gears "in line", but instead of putting sequential gears (1+2, 3+4, 5+6, 7+8 etc.) onto the same "synchroniser unit", first and reverse, second and fourth, third and fifth, and (one exception) sixth and seventh are put together. This way, the shifting sleeve for first and the shifting sleeve for second can be actuated at the same time – this halves the shifting times (instead of one actuator having to move "100 %", two actuators move "50 %" each at the same time, which effectively reduces the shifting speed). The latter design was used on the Porsche 997, for example. As you may have guessed, in theory, putting the gearbox into two gears at the same time is possible with the latter design, so a well-designed shifting programme has to be used to prevent this from happening. (And having a broken gearbox with this problem is no fun – especially not if the gearbox doesn't "know" that it's not supposed to shift into the "broken" gear…). (All of this (except for the anecdotes) can be found in Harald Naunheimer, Bernd Bertsche, Gisbert Lechner: Fahrzeuggetriebe – Grundlagen, Auswahl, Auslegung und Konstruktion, 2nd edition, Springer, Berlin/Heidelberg/New York 2007, ISBN 978-3-540-30625-2, p. 170–173. Best regards, --Johannes (Talk) (Contribs) (Articles) 13:17, 5 September 2020 (UTC)

Too technical

Having watched this subject on the Semi-automatic_transmission page, I think this is a huge improvement.

However this page and the wider subject is still presented with the wrong perspective. It reads like it's been written by a mechanic for other mechanics. The general populace of the planet usually do not care which car components are involved, and where they seek to learn, their path will start with "What happens when I put the car in D". Such is missing, and at the moment the people who buy care to drive them, and advertise them for sale, will find little of this information useful. CarbonPepper (talk) 10:21, 4 September 2020 (UTC)

Hi CarbonPepper. Thanks for sharing your thoughts. I agree, the article has greatly improved recently, but there is still room for improvements regarding how it explains the basic principal to the casual reader. Cheers, 1292simon (talk) 01:40, 5 September 2020 (UTC)

A detailed classification

It would be useful to include in some general article a comprehensive and well-defined classification of transmissions. What do you think of the following?

• Manual transmissions: Non-synchronized and, synchronized. Modern ones may include technologies that improve the shifting such as Toyota's iMT (not to be confused with the semi-automatic term) or, the synchronized down shift rev-matching system.
• Automatic transmissions: Automatized clutch and gear shifting functions.
  • Hydraulic automatic transmissions (HATs): Current ones have several "internal" clutches not accessible to the driver thru pedals. These are the oldest "commercially successful" kind. Also known as Torque Converter automatic transmissions.
  • Manumatic transmissions (MMTs): The modern usage of the automotive term manumatic denotes an automatic transmission that allows the driver to select a specific gear, typically using paddle-shifters, steering wheel-mounted push-buttons, or "+" and "-" controls on the gear selector. The driver often does not have full control of the gear selection, as most manumatic modes will deny a gear change request that would result in the engine stalling (from too few RPM) or over-revving. Some transmissions will hold the requested gear indefinitely, while others will return to automatic gear selection after a period of time.
  • Dual-clutch automatic transmissions (DCTs): They might have several clutches too but they are grouped into two parallel sub-systems. No torque converter, clutch packs instead. Most dual-clutch transmissions have also a "manual" mode which requires the drives to select gears via paddle shifters; so, if that is the case, a DCT might be identified as as a sequential clutchless transmission. Besides, internally they are implemented with two separate clutch systems for odd and even gear sets. The design is often similar to two separate manual transmissions with their respective clutches contained within one housing, and working as one AUTOMATIC unit. So, due to the way they are implemented, some people do not classify them as automatic transmissions but as AMTs.
  • Continuous Variable Transmissions (CVTs): No regular clutch but a centrifugal one. Many currents CVTs "fake" gear shifting to offer a "sport mode". In that case, they provide sequential upshifting and downshifting controls which allow you to "jump" from one point to another in the torque continuum. For that reason, they might also be classified as an AMTs.
• Semi-automatic transmissions: In the broad sense, it is an umbrella term for non-sequential and sequential clutchless manual transmissions and, automated manual transmissions. In the strict sense, the term refers only to the first.
  • Non-sequential clutchless transmissions: The clutch is "internal" and its behavior is governed by the car, not the driver. The driver selects the gears and the transmission does not require him to choose gears sequentially. Example: Hyundai and Kia's iMT.
  • Sequential clutchless transmissions: Similar to the previous one but there is no way to skip gears. Used in race motorcycles and cars.
• Automated manual transmissions (AMTs): It is a manual transmission with an automatized clutch (which is not accessible to the driver through a pedal) and an ASSISTED or AUTOMATIC gear shifting function. If the second function is assisted but not fully automatic, an AMT cannot be classified as automatic but as semi-automatic. If the latter function is not implemented, they are simply clutchless transmissions. Most modern implementations of this transmission function in a sequential mode, where the driver can only upshift or downshift by one gear at a time. However, this is not the case for all modern transmissions. For example, BMW's "SMG" and Ferrari's "F1" transmissions can skip gears on both downshifts and upshifts, when selecting gears manually via the steering wheel-mounted paddle-shifters. Example: Toyota's MMT. For background, there are two types of AMTs: single-clutch and dual-clutch. Single-clutch AMTs are older, lurch-prone and generally unpleasant; the good news is that only the Smart Fortwo and some exotic sports cars use them. Dual-clutch AMTs, on the other hand, are designed to eliminate lurching, and the best units provide incredibly quick yet perfectly smooth shifts. Most current AMT-equipped cars use dual-clutch technology. AFAIK, the 1st transmission capable of operating this way was the 1942 Hudson Commodore Drive Master which, in fact, had 3 modes: manual, semi-automatic and automatic. So, the Drive-Master might represent another category on its own.

I think transmissions should be classified depending on how they function and not necessarily on how they are implemented as some modern transmissions resemble manual transmissions but function as automatic ones.

George Rodney Maruri Game (talk) 09:16, 19 March 2022 (UTC)