Editing Semi-automatic transmission

{{short description|Type of multi-speed motor vehicle transmission}}
{{Use dmy dates|date=September 2022}}
A '''semi-automatic transmission''' is a multiple-speed [[Transmission (mechanics)|transmission]] where part of its operation is [[Automation|automated]] (typically the actuation of the [[clutch]]), but the driver's input is still required to launch the vehicle from a standstill and to manually change gears. Semi-automatic transmissions were almost exclusively used in motorcycles and are based on conventional [[manual transmission]]s or [[sequential manual transmission]]s, but use an automatic clutch system. But some semi-automatic transmissions have also been based on standard hydraulic [[automatic transmissions]] with [[torque converter]]s and [[Epicyclic gearing|planetary gearsets]].<ref>{{cite web |last1=Wan |first1=Mark |title=AutoZine Technical School, Manual Transmission |url= https://www.autozine.org/technical_school/gearbox/Gearbox_Manual.html |website=autozine.org |date=2019 |access-date=17 November 2020}}</ref><ref>{{cite web |title=How to Shift Gears on a Motorcycle |url= https://www.wikihow.com/Shift-Gears-on-a-Motorcycle |website=wikiHow |access-date=17 November 2020 |date=21 September 2020}}</ref>

Names for specific types of semi-automatic transmissions include ''clutchless manual'',<ref name="autonews1">{{cite web |url= https://www.autonews.com/article/20010401/SUB/104010719/the-next-shift-the-clutchless-manual |title=The next shift: The clutchless manual |website=autonews.com |date=13 December 2005 |access-date=29 February 2020}}</ref> ''auto-manual'',<ref>{{cite web |title=1993 Ferrari Mondial T Cabriolet Valeo |url= https://bringatrailer.com/listing/1993-ferrari-mondial-t-cabriolet-2/ |website=Bring a Trailer |date=October 2018 |access-date=18 November 2020}}</ref><ref>{{cite web|url=https://bringatrailer.com/listing/1992-ferrari-mondial-t-cabriolet-3/|title=1992 Ferrari Mondial T Cabriolet Valeo Transmission|date=20 July 2023 }}</ref> ''auto-clutch manual'',<ref name="yamahamotorsports.com">{{cite web|url=https://www.yamahamotorsports.com/trail-motorcycle/models/tt-r110e|title=2022 Yamaha TT-R110E Trail Motorcycle – Photo Gallery, Video, Specs, Features, Offers, Inventory and more|website=www.yamahamotorsports.com|access-date=16 August 2020|archive-date=29 September 2020|archive-url=https://web.archive.org/web/20200929011521/https://www.yamahamotorsports.com/trail-motorcycle/models/tt-r110e|url-status=dead}}</ref><ref>Archived at [https://ghostarchive.org/varchive/youtube/20211205/XC29R9CSx-M Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20201209164403/https://www.youtube.com/watch?v=XC29R9CSx-M Wayback Machine]{{cbignore}}: {{cite web| url = https://www.youtube.com/watch?v=XC29R9CSx-M| title = How to make any bike an AUTOMATIC | website=YouTube}}{{cbignore}}</ref> and ''paddle-shift'' transmissions.<ref>{{cite web|url= http://www.geartronics.co.uk/paddleshift.htm|title = Geartronics – Sequential gearbox electronic systems – Professional paddle shift system}}</ref><ref>{{cite web|url= https://www.hewland.com/wpcproduct/semi-auto-systems/|title = Semi-Auto Systems}}</ref><ref>{{cite web|url= https://www.hewland.com/race-series-control-components/|title = Control components for race series reduce cost, improve competition}}</ref> These systems facilitate gear shifts for the driver by operating the clutch system automatically, usually via [[switch]]es that trigger an [[actuator]] or [[servomechanism|servo]], while still requiring the driver to manually shift gears. This contrasts with a [[preselector gearbox]], in which the driver selects the next gear ratio and operates the pedal, but the gear change within the transmission is performed automatically.

The first usage of semi-automatic transmissions was in automobiles, increasing in popularity in the mid-1930s when they were offered by several American car manufacturers. Less common than traditional hydraulic automatic transmissions, semi-automatic transmissions have nonetheless been made available on various car and motorcycle models and have remained in production throughout the 21st century. Semi-automatic transmissions with paddle shift operation have been used in various [[Auto racing|racing cars]], and were first introduced to control the electro-hydraulic gear shift mechanism of the [[Ferrari 640]] [[Formula One car]] in 1989. These systems are currently used on a variety of top-tier racing car classes; including [[Formula One]], [[IndyCar]], and [[touring car racing]]. Other applications include motorcycles, trucks, buses, and [[Rail transport|railway vehicles]].

== Design and operation ==
Semi-automatics facilitate easier [[gear shift]]s by removing the need to depress a clutch pedal or lever at the same time as changing gears. Most cars that have a semi-automatic transmission are not fitted with a standard clutch pedal since the clutch is remotely controlled. Similarly, most motorcycles with a semi-automatic transmission are not fitted with a conventional clutch lever on the [[Motorcycle handlebar|handlebar]].

=== Clutchless manual transmissions ===
Most semi-automatic transmissions are based on conventional manual transmission. They can be partially automated transmission. Once the clutch becomes automated, the transmission becomes semi-automatic. However, these systems still require manual gear selection by the driver. This type of transmission is called a ''clutchless manual'' or an ''automated manual''.

Most semi-automatic transmissions in older passenger cars retain the normal H-pattern shifter of a manual transmission; similarly, semi-automatic transmissions on older motorcycles retain the conventional foot-shift lever, as on a motorcycle with a fully manual transmission. However, semi-automatics systems in newer motorcycles, racing cars, and other types of vehicles often use gear selection methods such as shift paddles near the [[steering wheel]] or triggers near the [[Motorcycle handlebar|handlebars]].<ref>{{cite web |title=Electronic Shift Transmission |url= https://shiftfx.com/electronic-shift-transmission |website=shiftfx.com |access-date=17 November 2020}}</ref><ref>{{cite web |title=Motorsport, Motorcycle race & kit car quickshifter systems |url= https://www.quickshifters.com |website=quickshifters.com |access-date=17 November 2020}}</ref><ref name="flatshifter.com">{{cite web|url=https://www.flatshifter.com/flatshifter-max-electronic-gear-selector-kit/|title = Flatshifter Max (Electronic Gear Selector Kit)}}</ref><ref>{{cite web|url=https://powersportsbusiness.com/top-stories/2016/06/08/yamaha-introduces-new-yxz1000rss-with-paddle-shifting/|title = Yamaha introduces new YXZ1000R SS with paddle shifting &#124; Powersports Business|date = 8 June 2016}}</ref><ref>{{Cite web |title=Formula Racecar Paddle Shifters |url=http://www.eecs.ucf.edu/seniordesign/su2015fa2015/g05/files/SDI/1.%20InitialDocument.pdf |access-date=16 October 2023 |website=[[University of Central Florida College of Engineering and Computer Science]]}}</ref><ref>{{Cite web |title=2014_RT Spec Sheet EN.pdf |url=https://can-am.brp.com/content/dam/canam-spyder/Canada/English/MY2014/Documents/Lineup/2014_RT%20Spec%20Sheet%20EN.pdf |access-date=16 October 2023 |website=can-am.brp.com}}</ref><ref>{{cite web|url=https://www.lemans.org/en/news/the-history-of-the-paddle-shift/2922|title = The history of the 'paddle shift'}}</ref>

Several different forms of automation for clutch actuation have been used over the years, from [[hydraulic actuator|hydraulic]], [[pneumatic actuator|pneumatic]], and [[Electromechanics|electromechanical]] clutches to [[Vacuum pump|vacuum-operated]],<ref>{{Cite web |title=Hudson Drivemaster Service Info |url=http://hudsonterraplane.com/tech/other/DrivemasterServiceInformation.pdf |access-date=16 October 2023 |website=hudsonterraplane.com}}</ref> [[electromagnetic clutch|electromagnetic]], and even [[centrifugal clutch]]es. [[Fluid coupling]]s (most commonly and formerly used in early automatic transmissions) have also been used by various manufacturers, usually alongside some form of mechanical friction clutch, to prevent the vehicle from stalling when coming to a standstill or at [[Idle (engine)|idle]].

A typical semi-automatic transmission design may work by using [[Hall effect sensor]]s or [[Miniature snap-action switch|micro switches]] to detect the direction of the requested shift when the gear stick is used. These sensors' output, combined with the output from a sensor connected to the [[gearbox]] which measures its current speed and gear, is fed into a [[transmission control unit]], [[electronic control unit]], [[engine control unit]], or [[microprocessor]],<ref>{{cite news|url= https://www.independent.co.uk/arts-entertainment/auto-biography-the-saab-900-turbo-sensonic-in-0-60-seconds-by-john-fordham-1304895.html |title = Auto Biography the Saab 900 Turbo Sensonic in 0–60 Seconds by John|website = [[Independent.co.uk]]|date = 23 October 2011}}</ref><ref>{{cite web|url= https://www.saabplanet.com/how-stuff-works-saab-900-ng-sensonic-clutchless-technology-in-practice/|title = How Stuff Works: Saab Sensonic (Clutchless Technology in Practice)|date = 28 January 2019}}</ref> or another type of electronic control system. This control system then determines the optimal timing and torque required for smooth clutch engagement.

The electronic control unit powers an actuator, which engages and disengages the clutch in a smooth manner. In some cases, the clutch is actuated by a [[servomotor]] coupled to a gear arrangement for a [[linear actuator]], which, via a [[hydraulic cylinder]] filled with [[hydraulic fluid]] from the [[Brake|braking system]], disengages the clutch. In other cases, the internal clutch actuator may be completely electric, where the main clutch actuator is powered by an [[electric motor]] or [[solenoid]], or even pneumatic, where the main clutch actuator is a [[pneumatic actuator]] that disengages the clutch.

A clutchless manual system, named the ''[[Autostick]]'', was a semi-automatic transmission introduced by [[Volkswagen]] for the 1968 model year. Marketed as the ''Volkswagen Automatic Stickshift'', a conventional three-speed manual transmission was connected to a vacuum-operated automatic clutch system. The top of the gear stick was designed to  depress and activate an electric switch, i.e. when touched by the driver's hand. When pressed, the switch operated a 12-volt [[Solenoid valve|solenoid]], which in turn operated the vacuum clutch actuator, thus disengaging the clutch and allowing shifting between gears. With the driver's hand removed from the gearshift, the clutch would re-engage automatically. The transmission was also equipped with a torque converter, allowing the car to idle in gear like with an automatic, as well as stop and start from a standstill in any gear.<ref>{{cite web |title=How Does An Autostick Work? |url= http://vwar.org/forum/index.php?topic=903.0 |publisher=VW Automatic Register |date=8 October 2009 |access-date=11 November 2020}}</ref><ref>{{cite web |title=Autostick |url= http://www.vw-resource.com/automatic.html |publisher=Rob and Dave's Aircooled Volkswagen Web Pages |access-date=11 November 2020}}</ref><ref>{{cite web|url=https://www.cargurus.com/Cars/Discussion-c6916_ds457882#:~:text=Almost%20all%20of%20the%20original,gear%20stick%20to%20change%20gears.|title = Automatic or standard (Volkswagen Beetle) – CarGurus}}</ref>

=== Automated manual transmissions ===
{{main|Automated manual transmission}}
[[File:Paddle Shifter Honda Accord 2013.JPG|thumb|Paddle shifter on a car.]]
Starting in the late 1990s, automotive manufacturers introduced what is now called an [[automated manual transmission]] (AMT), which is mechanically similar to, and has its roots in, earlier clutchless manual transmission systems. An AMT functions in the same way as older semi-automatic and clutchless manual transmissions, but with two exceptions; it is able to both operate the clutch and shift automatically, and does not use a torque converter. Shifting is done either automatically from a [[transmission control unit]] (TCU), or manually from either the shift knob or shift paddles mounted behind the steering wheel. AMTs combine the fuel efficiency of manual transmissions with the shifting ease of automatic transmissions. Their biggest disadvantage is poor shifting comfort due to the mechanical clutch being disengaged by the TCU, which is easily noticeable as "jolting".{{Citation needed|date=October 2021}} Some transmission makers have tried solving this issue by using oversized synchronizer rings and not fully opening the clutch during shifting—which works in theory, but as of 2007, there have not been any series production cars with such functions.{{Update inline|date=October 2021}} In passenger cars, modern AMTs generally have six speeds (though some have seven) and a rather long gearing. In combination with a smart-shifting program, this can significantly reduce fuel consumption. In general, there are two types of AMTs: integrated AMTs and add-on AMTs. Integrated AMTs were designed to be dedicated AMTs, whereas add-on AMTs are conversions of standard manual transmissions into AMTs.{{Citation needed|date=October 2021}}

An automated manual transmission may include a fully automatic mode where the driver does not need to change gears at all.<ref name="x-engineer1">{{cite web |url=https://x-engineer.org/automotive-engineering/drivetrain/transmissions/automated-manual-transmissions-amt/ |title=Automated Manual Transmission (AMT) |website=x-engineer.org |access-date=2020-02-29 }}</ref> These transmissions can be described as a standard manual transmission with an automated clutch and automated gear shift control, allowing them to operate in the same manner as traditional automatic transmissions. The TCU automatically shifts gears if, for example, the engine is [[redline]]d. The AMT can be switched to a clutchless manual mode wherein one can upshift or downshift using a [[Center console (automobile)|console]]-mounted shift selector or paddle shifters.<ref>{{cite news|last=Woodyard|first=Chris|title=Among bells and whistles, cars shift to buttons, knobs|url= https://www.usatoday.com/story/money/cars/2014/08/10/cars-shifting-knobs-buttons/13721433/|access-date=2021-10-15|website=USA Today|language=en-US}}</ref> It has a lower cost than conventional automatic transmissions.<ref name="zf1">{{cite web |url=https://www.zf.com/products/en/cars/products_29280.html |title=Automated Manual Transmission |website=zf.com |access-date=2020-02-29 |archive-date=26 September 2020 |archive-url=https://web.archive.org/web/20200926015226/https://www.zf.com/products/en/cars/products_29280.html |url-status=dead }}</ref>

The automated manual transmission (trade names include ''SMG-III'') is not to be confused with "[[manumatic]]" automatic transmission (marketed under trade names such as ''Tiptronic'', ''Steptronic'', ''Sportmatic'', and ''[[Geartronic]]''). While these systems seem superficially similar, a manumatic uses a torque converter like an automatic transmission, instead of the clutch used in the automated manual transmission. An automated manual can give the driver full control of the gear selection, whereas a manumatic will deny a gear change request that would result in the engine stalling (from too few [[RPM]]) or over-revving.<ref name="x-engineer1" /> The automatic mode of an automated manual transmission at low or frequent stop start speeds is less smooth than that of manumatics and other automatic transmissions.<ref>{{cite web|url=http://www.leftlanenews.com/review-m5s-smg-sucks-all-the-joy-from-experience.html|title=Review: M5's SMG "sucks all the joy" from experience |website=leftlanenews.com |access-date= 24 March 2019}}</ref>

=== Sequential manual transmissions ===
Several semi-automatic transmissions used by motorcycles and racing cars are actually mechanically based on [[sequential manual transmission]]s. Semi-automatic motorcycle transmissions generally omit the clutch lever, but retain the conventional heel-and-toe foot shift lever.<ref>{{cite web |url=https://www.wikihow.com/Shift-Gears-on-a-Motorcycle |title=How to Shift Gears on a Motorcycle |website=wikiHow}}</ref><ref name="itstillruns.com">{{cite web |url=https://itstillruns.com/shift-automatic-transmission-dirt-bike-7577353.html |title=How to Shift a 4 Speed Semi Automatic Transmission on a Dirt Bike |website=It Still Runs}}</ref><ref>{{cite web |url= https://www.cycleworld.com/top-automatic-motorcycles-you-can-buy-in-2019/ |title = Top Automatic Motorcycles You Can Buy in 2019}}</ref><ref name="autowise.com">{{cite web |url = https://autowise.com/automatic-dirt-bike/ |title = 10 Best Automatic Dirt Bike Models |date= 17 May 2021 |access-date=18 August 2020|archive-date = 25 October 2021 |archive-url = https://web.archive.org/web/20211025210426/https://autowise.com/automatic-dirt-bike/ |url-status = dead}}</ref><ref name="dirtbikehouse.com">{{cite web |url= https://dirtbikehouse.com/what-is-a-semi-automatic-dirt-bike/ |title = What is a Semi-Automatic Dirt Bike and How does it work? |date = 19 January 2020}}</ref><ref name="ktm.com">{{cite web |url=https://www.ktm.com/en-int/error-page.html |title=Error Page |website=www.ktm.com}}</ref>

Semi-automatic motorcycle transmissions are based on conventional sequential manual transmissions and typically use a [[centrifugal clutch]].<ref>{{cite web |date=8 May 2000 |title=How Chain Saws Work |url=https://home.howstuffworks.com/chainsaw4.htm}}</ref> At idle speed, the engine is disconnected from the gearbox input shaft, allowing both it and the bike to [[freewheel]], unlike with torque converter automatics, there is no [[idle creep]] with a properly adjusted centrifugal clutch. As the engine speed rises, counterweights within the clutch assembly gradually pivot further outwards until they start to make contact with the inside of the outer housing and transmit an increasing amount of engine power and torque. The effective "bite point" or "biting point"<ref>{{cite web |title=biting point |url= https://dictionary.cambridge.org/dictionary/english/biting-point |access-date=2021-10-15 |website=Cambridge Dictionary |language=en}}</ref> is found automatically by equilibrium, where the power is transmitted through the (still-slipping) clutch is equal to what the engine can provide. This allows relatively fast full-[[throttle]] takeoffs (with the clutch adjusted so the engine is at peak torque) without the engine slowing or being bogged down, as well as more relaxed starts and low-speed maneuvers at lower throttle and [[Revolutions per minute|RPMs]].

== Usage in passenger cars ==
=== 1900s–1920s ===
[[File:1913-1923 Amédée BOLLÉE Fils Type F Berline crop.jpg|thumb|Bollée Type F Torpedo with gear shift ring located inside the steering wheel]]

In 1901, [[Amédée Bollée]] developed a method of shifting gears that did not require the use of a clutch and was activated by a ring mounted within the steering wheel.<ref name="lemans-paddle">{{cite web |title=The history of the 'paddle shift' |url= https://www.lemans.org/en/news/the-history-of-the-paddle-shift/2922 |website=lemans.org |date=21 February 2011 |access-date=2020-02-16}}</ref> One car using this system was the 1912 [[Léon Bollée Automobiles|Bollée]] Type F Torpedo.

=== 1930s–1940s ===
Prior to the arrival of the first mass-produced hydraulic automatic transmission (the [[General Motors]] [[Hydramatic|Hydra-Matic]]) in 1940, several American manufacturers offered various devices to reduce the amount of clutch or shifting input required.<ref>{{cite web|url= https://www.caranddriver.com/research/a31862769/how-does-an-automatic-transmission-work/ |title = How Does an Automatic Transmission Work?|date = 13 April 2020}}</ref> These devices were intended to reduce the difficulty of operating the [[Non-synchronous transmission|unsynchronised manual transmissions]], or "crash gearboxes", that were commonly used, especially in stop-start driving.

An early step towards automated transmissions was the 1933–1935 [[REO Motor Car Company|REO]] Self-Shifter,<ref name="hagerty.com">{{cite web |title=6 of the worst automatic transmissions ever |url= https://www.hagerty.com/media/maintenance-and-tech/6-of-the-worst-automatic-transmissions-ever/ |website=hagerty.com |access-date=9 August 2020 |date=8 August 2019}}</ref><ref>{{cite web|url= https://www.autoindustriya.com/features/making-automatic-sense.html |title = Making Automatic Sense – Feature Stories|date = 29 September 2010}}</ref><ref>{{cite web|url= https://www.caranddriver.com/research/a31884931/what-is-an-automatic-car/ |title = What is an Automatic Car?|date = 13 April 2020}}</ref><ref>{{cite web|url=https://www.caranddriver.com/research/a31862769/how-does-an-automatic-transmission-work/ |title = How Does an Automatic Transmission Work?|date = 13 April 2020}}</ref> which automatically shifted between two forward gears in the "forward" mode (or between two shorter gear ratios in the "emergency low" mode). Standing starts required the driver to use the clutch pedal. The Self-Shifter first appeared in May 1933 and was offered as standard on the Royale and as an option on the Flying Cloud S-4.<ref>{{cite web|url= http://auto.howstuffworks.com/reo-cars1.htm |title=How Reo Cars Work|date=15 June 2007|access-date=24 October 2017}}</ref>

In 1937, the four-speed [[Oldsmobile]] Automatic Safety Transmission was introduced on the [[Oldsmobile Six]] and Oldsmobile Eight models.<ref name="hagerty.com"/> It used a planetary gearset with a clutch pedal for starting from a standstill and switching between the "low" and "high" ranges.<ref>{{cite web |title=The Oldsmobile automatic safety transmission operated by the short lever shown on the steering column. |url= https://digitalcollections.nypl.org/items/510d47db-bb52-a3d9-e040-e00a18064a99 |website=nypl.org |access-date=9 August 2020 |language=en}}</ref><ref>{{cite web |title=No clutch to press! No gears to shift! |url= https://www.autonews.com/article/19970818/ANA/708180702/no-clutch-to-press-no-gears-to-shift |website=autonews.com |access-date=9 August 2020 |language=en |date=18 August 1997}}</ref><ref>{{cite web |title=How Oldsmobile Cars Work |url=https://auto.howstuffworks.com/oldsmobile-cars1.htm |website=howstuffworks.com |access-date=9 August 2020 |language=en |date=20 June 2007 |archive-date=20 September 2020 |archive-url=https://web.archive.org/web/20200920073229/https://auto.howstuffworks.com/oldsmobile-cars1.htm |url-status=dead }}</ref> The Automatic Safety Transmission was replaced by the fully-automatic Hydra-Matic for the 1940 model year.<ref>{{cite web|url= https://quality-coaches.com/transmission-repair/the-evolution-of-the-auto-transmission/|title=The Evolution of the Auto Transmission |website=quality-coaches.com }}</ref><ref>{{cite web|url= https://driving.ca/chevrolet/corvette/auto-news/news/hail-hydra-matic-the-rise-of-the-automatic-transmission |title=Shifting Times: The rise of the automatic transmission|date=6 January 2015}}</ref>

The 1938–1939 [[Buick Special]] was available with another Self-Shifter 4-speed semi-automatic transmission,<ref>{{cite web |title=How Buick Works |url= https://auto.howstuffworks.com/buick.htm |website=howstuffworks.com |access-date=8 August 2020 |language=en |date=5 June 2007}}</ref><ref>{{Cite web |title=1938-Buick-Folder.pdf |url=https://www.xr793.com/wp-content/uploads/2018/10/1938-Buick-Folder.pdf |access-date=16 October 2023 |website=xr793.com}}</ref><ref>{{cite web|url= https://ateupwithmotor.com/terms-technology-definitions/hydramatic-history-part-1/2/|title=Hydra-Matic History: GM's First Automatic Transmission |website=ateupwithmotor.com |date=29 May 2010}}</ref> which used a manual clutch for starting from standstill and an automated clutch for gear changes.

The 1941 [[Chrysler]] [[Vacamatic|M4 Vacamatic]] transmission was a two-speed manual transmission with an integral underdrive unit, a traditional manual clutch, and a fluid coupling between the engine and the clutch.<ref>{{cite web |title=The M6 automatic transmission |url= https://www.allpar.com/mopar/m6.html |website=allpar.com |access-date=9 August 2020}}</ref><ref>{{cite web |title=Chrysler transmissions-Vacamatic semi-automatic |url= http://www.gottransmissions.com/blog/chrysler-transmissions/chrysler-transmissionsvacamatic-semi-automatic |website=gottransmissions.com |access-date=9 August 2020}}</ref><ref>{{cite web |title=How Chrysler Works |url=https://auto.howstuffworks.com/chrysler.htm |website=howstuffworks.com |access-date=9 August 2020 |language=en |date=1 June 2007}}</ref> The two-speed transmission had "high" and "low" ranges, and the clutch was used when the driver wanted to switch between ranges. For normal driving, the driver would press the clutch, select the High range, and then release the clutch. Once the accelerator was pressed, the fluid coupling would engage and the car would begin moving forward, with the underdrive unit engaged to provide a lower gear ratio. At between {{convert|15|and|20|mph|km/h|abbr=on}}, the driver would lift off the accelerator and the underdrive unit would disengage. The Vacamatic was replaced by a similar [[Presto-Matic|M6 Presto-Matic]] transmission for the 1946 model year.

Similar designs were used for the 1941–1950 [[Hudson Motor Car Company|Hudson]] Drive-Master<ref>{{cite web |title=1941–1947 Hudson |url=https://auto.howstuffworks.com/1941-1947-hudson3.htm |website=howstuffworks.com |access-date=8 August 2020 |language=en |date=16 September 2007 |archive-date=20 August 2008 |archive-url=https://web.archive.org/web/20080820183959/http://auto.howstuffworks.com/1941-1947-hudson3.htm |url-status=dead }}</ref><ref>{{cite web |title=Step-Down: The 1948–1954 Hudsons |url= https://ateupwithmotor.com/model-histories/step-down-hudsons/ |website=ateupwithmotor.com |access-date=8 August 2020 |date=6 September 2009}}</ref> and the ill-fated 1942 [[Lincoln Motor Company|Lincoln]] Liquimatic.<ref>{{cite web |title=Automatic Failure: Ford's 1942 Liquamatic Experiment |url=https://www.macsmotorcitygarage.com/automatic-failure-fords-1942-liquamatic-experiment/ |website=macsmotorcitygarage.com |access-date=8 August 2020 |date=7 February 2017}}</ref><ref>{{cite web |title=Automotive History: Lincoln's Liquamatic Drive – Failure to Upshift |url= https://www.curbsideclassic.com/automotive-histories/automotive-history-lincolns-liquamatic-drive-failure-to-upshift/ |website=curbsideclassic.com |date=30 May 2019 |access-date=8 August 2020}}</ref> Both of these combined a 3-speed [[manual transmission]] with automated shifting between the 2nd and 3rd gears, instead of the Vacamatic's "underdrive" unit.

The Packard Electro-Matic, introduced in the 1941 [[Packard Clipper]] and [[Packard 180]], was an early clutchless manual transmission that used a traditional friction clutch with automatic vacuum operation, which was controlled by the position of the accelerator.

=== 1950s–1960s ===
The [[Automotive Products]] manumatic system, available on the 1953 [[Ford Anglia#Anglia 100E (1953–1959)|Ford Anglia 100E]], was a vacuum-powered automatic clutch system that was actuated by a switch that was triggered whenever the gear stick was moved. The system could control the throttle cable (to keep the engine at the required RPM for the gear change) and vary the rate of clutch engagement.<ref>{{cite book |last1=Staton |first1=Abbey |title=Practical Automobile Engineering – Clutch Systems |pages=193–194}}</ref> The successive Newtondrive system, available on the 1957–1958 Ford Anglia, also had a provision for [[Choke valve|choke]] control. A similar product was the German [[Saxomat]] automatic clutch system, which was introduced in the mid-1950s and available on various European cars.<ref>{{cite web |title=Rare Rides: An Incredibly Rare 1965 Lancia Flaminia Super Sport Zagato |url= https://www.thetruthaboutcars.com/2020/05/rare-rides-an-incredibly-rare-1965-lancia-flaminia-super-sport-zagato/ |website=thetruthaboutcars.com |access-date=17 August 2020 |date=14 May 2020}}</ref>

The [[Citroën DS]], introduced in 1955, used a [[Hydraulic machinery|hydraulic system]] with a hydraulically-operated speed controller and idle speed step-up device to select gears and operate the otherwise conventional clutch. This allowed clutchless shifting with a single [[Steering column|column]]-mounted selector, while the driver simultaneously lifted off the accelerator to change gear. This system was nicknamed "Citro-Matic" in the U.S.

For the 1962 model year, [[American Motors Corporation|American Motors]] introduced the E-Stick, which eliminated the clutch pedal in the [[Rambler American]] with standard three-speed manual transmissions.<ref>{{cite book |last1=Kirk |first1=W.R. |last2=Puidokas |first2=S.V. |title=SAE Technical Paper Series |chapter=The Rambler E-Stick Transmission |chapter-url= https://www.sae.org/publications/technical-papers/content/620106/ |publisher=SAE Technical Paper |date=1 January 1962 |volume=1 |doi=10.4271/620106 |access-date=16 November 2020}}</ref> This automatic clutch used engine oil pressure as a hydraulic source and was available for less than $60.<ref>{{cite journal |title=New Rambler "E-Stick" rated big '62 auto news (advertisement) |journal=Popular Mechanics |date=January 1962 |volume=117 |issue=1 |page=223 |url= https://books.google.com/books?id=POEDAAAAMBAJ&q=rambler+e-stick+transmission&pg=PA223 |access-date=16 November 2020}}</ref> Compared to fully automatic transmissions of the time, the E-Stick offered the fuel economy of a stick-shift, with vacuum and electric switches controlling the clutch. The E-Stick three-speed transmission was offered on the larger [[Rambler Classic]] models, along with an overdrive unit.<ref>{{cite web |title=1964 X-Ray Rambler brochure |url= http://oldcarbrochures.org/United%20States/AMC/1964_AMC/1964-X-Ray-Rambler-Brochure/slides/1964_X-Ray_Rambler-20-21.html |website=oldcarbrochures.org |access-date=16 November 2020 |page=20}}</ref> The system was only available with 6-cylinder engines, and the lack of a clutch proved unpopular, so it was discontinued after 1964.<ref>{{cite journal |last1=Whitmyer |first1=Marty |title=Behind the scenes at new car showings |journal=Commercial Car Journal |date=1964 |url= https://books.google.com/books?id=6JknAAAAMAAJ&q=1964+Behind+the+scenes+at+new+car+showings+e-stick |quote=The "E" stick transmission offered by AMC in '64 has been dropped. |access-date=16 November 2020}}</ref>

The 1967 [[Volkswagen]] WSK (''Wandlerschaltkupplungsgetriebe''; English: ''Torque converter shift/clutch gearbox''), used in the [[Volkswagen Beetle|Beetle]], [[Volkswagen Type 3|Type 3]] and [[Volkswagen Karmann Ghia|Karmann Ghia]], was one of the first gearboxes of its kind, with an automatic mechanical clutch and a torque converter. It was also known as the [[Autostick]]. Shifting was done manually by the driver. The automatic mechanical clutch allowed the car to accelerate from a stop, whereas the torque converter enabled it to do so in any gear. Dampening engine vibrations and providing torque multiplication, it functioned as a sort of "reduction gearbox", so the actual mechanical gearbox only needed three forward gears (this is why conventional automatic transmissions with torque converters normally have fewer gears than manual transmissions). The WSK had no "first" gear; instead, the first gear was converted into reverse gear, and the second gear was labeled first (with the third and fourth gears respectively being labeled second and third).<ref>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.</ref>

The [[Powerglide#Torque Drive|Chevrolet Torque-Drive]] transmission, introduced on the 1968 [[Chevrolet Chevy II / Nova#Third generation|Chevrolet Nova]] and [[Chevrolet Camaro (first generation)|Camaro]], is one of a few examples where a semi-automatic transmission was based on a conventional hydraulic automatic transmission (rather than a standard manual transmission). The Torque-Drive was essentially a 2-speed [[Powerglide]] automatic transmission without the vacuum modulator, requiring the driver to manually shift gears between "Low" and "High". The quadrant indicator on Torque-Drive cars was "Park-R-N-Hi-1st". The driver would start the car in "1st," then move the lever to "Hi" when desired. The Torque-Drive was discontinued at the end of 1971 and replaced by a traditional hydraulic automatic transmission. Other examples of semi-automatic transmissions based on hydraulic automatics were the Ford 3-speed Semi-Automatic Transmission used in the 1970–1971 [[Ford Maverick (1970)|Ford Maverick]], early versions of Honda's 1972–1988 [[Hondamatic]] 2-speed and 3-speed transmissions, and the [[Daihatsu]] Diamatic 2-speed transmission used in the 1985–1991 [[Daihatsu Charade]].

=== Other examples ===
[[File:Saab_Sensonic_transmission.jpg|thumb|right|Illustration of Saab's ''Sensonic'' clutchless manual transmission system.]]
{| class="wikitable sortable"
|-
! Years !! Name !! Notes
|-
| 1953–1954 || [[Plymouth (automobile)|Plymouth]] [[Hy-Drive]]|| Torque converter added to a 3-speed manual transmission so it could be driven solely in top gear (to avoid using the manual clutch).
|-
| 1956–1963 || [[Renault]] Ferlec || Automatic electromagnetic clutch. Used in the [[Renault Dauphine]].<ref>{{cite web |title=1956–1968 Renault Dauphine |url= https://auto.howstuffworks.com/1956-1968-renault-dauphine.htm/printable |website=howstuffworks.com |access-date=8 August 2020 |language=en |date=20 August 2007}}</ref><ref>{{cite web |title=Renault Dauphine buyer's guide: what to pay and what to look for |url= https://www.classicandsportscar.com/features/buyers-guide-renault-dauphine |website=classicandsportscar.com |access-date=8 August 2020}}</ref>
|-
| 1957–1961 || [[Mercedes-Benz]] Hydrak || Automatic vacuum-powered clutch, plus a fluid coupling for standing starts.<ref>{{cite web|url= http://www.mbzponton.org/valueadded/maintenance/hydrak.htm |title=Mercedes-Benz Ponton Hydrak Automatic Clutch |first=Jeff|last=Miller|website=mbzponton.org|access-date=24 October 2017}}</ref>
|-
| 1959–???? || [[Citroën]] Traffi-Clutch  || Automatic centrifugal clutch. Used in the [[Citroën 2CV]], [[Citroën Traction Avant]], and [[Citroën Dyane]].
|-
| 1965–1990 || [[HQM Sachsenring GmbH|VEB Sachsenring]] Hycomat || Automatic electro-hydraulic clutch. Used in the [[Trabant 601]].
|-
| 1966–???? || [[Simca]] automatic clutch || Automatic clutch plus a torque converter. Used in the [[Simca 1000]].<ref>{{cite web |title=Theme: Simca – 1965 1000 GLS Short Road Test |url= https://driventowrite.com/2017/03/04/1965-simca-1000-gls-short-road-test/ |website=driventowrite.com |access-date=8 August 2020 |date=4 March 2017}}</ref><ref>{{cite web |title=Simca 1100 |url= https://www.uniquecarsandparts.com.au/car_info_simca_1100 |website=uniquecarsandparts.com.au |access-date=8 August 2020}}</ref><ref>{{cite web|url= https://www.flickr.com/photos/njsimca/3082847153/in/photostream/ |title=Simca 1000 GLA Automatique 1966 lever |publisher=Flickr.com |date=4 December 2008 |access-date=2020-03-01}}</ref><ref>{{cite web |url= http://www.rootes-chrysler.co.uk/simca-cars/simca-1000.html | title = Simca 1000 cars | publisher = VerticalScope |work = Rootes-Chrysler.co.uk | access-date = 8 August 2012 | last = Thompson | first = Andy }}</ref>
|-
| 1967–1977 || [[NSU Motorenwerke|NSU]] automatic clutch || Automatic vacuum-powered clutch plus a torque converter. Used in the [[NSU Ro 80]].
|-
| 1967–1976 || [[Porsche]] Sportomatic || Automatic vacuum-powered clutch plus a torque converter. Used in the [[Porsche 911 (classic)|Porsche 911]].<ref>{{cite web|url= https://www.caranddriver.com/news/a15366473/shift-this-a-history-of-porsches-sportomatic-tiptronic-and-pdk-transmissions/ |title = Shift This: A History of Porsche's Sportomatic, Tiptronic, and PDK Transmissions|date = 10 December 2013}}</ref><ref>{{cite web|url= https://www.total911.com/porsche-911-rs-book-volume-2-now-on-sale/ |title=Porsche 911 RS Book Volume 2 now on sale|date=28 June 2014}}</ref>
|-
|1968–1971
|[[Subaru]] Autoclutch
|Automatic electromagnetic clutch.<ref>{{cite web|title=Subaru 360 Sedan Auto-Clutch Service Manual|url= http://www.mysubaru360.com/manuals_and_documents/Subaru_360_Autoclutch_manual.pdf |access-date=2021-10-18}}</ref> Used in the [[Subaru 360]].<ref>{{cite web|date=6 January 2021|title=Once "Cheap and Ugly," the Subaru 360 is having an unexpected moment|url= https://www.hagerty.com/media/valuation/once-cheap-and-ugly-the-subaru-360-is-having-an-unexpected-moment/ |access-date=2021-10-18|website=Hagerty Media|language=en-US}}</ref>
|-
| 1968–1976 || [[Volkswagen]] [[Autostick]]|| Automatic electro-pneumatic clutch plus a torque converter. Used in the [[Volkswagen Beetle]] and [[Volkswagen Karmann Ghia]].<ref name="VWhalb">{{cite web | url = http://www.kaeferclub-siegerland.de/technik/automatic.htm | archive-url = https://web.archive.org/web/20130410022102/http://www.kaeferclub-siegerland.de/technik/automatic.htm | archive-date = 10 April 2013 | title = VW Automatic – der Käfer mit halbautomatischem Getriebe | trans-title = VW Automatic – the Beetle with a semi-automatic transmission | language = de | last = Dingeldein | first = Wolfgang | date = 2011 | work = Käfertreter Siegerland }}</ref>
|-
| 1971–1980 || Citroën C-matic || Automatic clutch plus a torque converter. Used in the [[Citroën GS]] and [[Citroën CX]]. Originally called Convertisseur in GS models.
|-
| 1991–1993 || [[Ferrari]] Valeo|| Automatic electro-mechanical clutch. Used in the [[Ferrari Mondial#Mondial t|Ferrari Mondial t]].<ref>{{cite web|url=https://www.vwvortex.com/threads/the-archive-1991-ferrari-mondial-t-with-valeo-automatic-clutch.4519537/|title=The Archive – 1991 Ferrari Mondial t – with Valeo...|website=VW Vortex – Volkswagen Forum|date=3 May 2011 }}</ref><ref>{{cite web|url=https://www.ferrari.com/en-US/auto/mondial-t|title=Ferrari Mondial T (1989) - Ferrari.com|website=www.ferrari.com}}</ref>
|-
| 1992–1998 || [[Ruf Automobile|RUF]] [[Fichtel & Sachs|{{abbr|EKS|Electronic Clutch System}}]]|| Automatic electro-hydraulic clutch. Used in the [[Ruf BTR#BTR 3.8|Ruf BTR]]<ref>{{cite web|title=RUF Automobile GMBH – Manufaktur für Hochleistungsautomobile – History|url= https://ruf-automobile.de/en/performance/historie/}}</ref> and [[Ruf BTR2]].
|-
| 1993–1998 || [[Saab Automobile|Saab]] Sensonic || Automatic electro-hydraulic clutch.<ref>{{cite web|date=13 December 2005|title=Saab Shelves Sensonic Transmission|url= https://www.autonews.com/article/19980216/ANA/802160766/saab-shelves-sensonic-transmission}}</ref><ref>{{cite web| url = https://www.orlandosentinel.com/news/os-xpm-1994-05-12-9405110114-story.html| title = SAAB DEVELOPS STICK WITH NO CLUTCH – Orlando Sentinel| date = 12 May 1994}}</ref> Used in the [[Saab 900 NG]].
|-
| 2020–present || [[Hyundai Motor Company|Hyundai]]/[[Kia]] {{abbr|iMT|Intelligent Manual Transmission}}|| Automatic electro-hydraulic clutch. Used in the [[Hyundai Venue]], [[Hyundai i20]], and [[Kia Sonet]]. The gear stick has a shift pattern similar to a fully manual car, unlike AMTs with only sequential gear selection.<ref>{{cite web|date=10 July 2020|title=Hyundai Venue Offers Manual Transmission With No Clutch Pedal|url= https://www.motortrend.com/news/hyundai-venue-imt-clutchless-manual-transmission/ |access-date=2021-10-18 |website=MotorTrend|language=en}}</ref>
|}

== Usage in motorcycles ==
An early example of a semi-automatic motorcycle transmission was the use of an automatic centrifugal clutch in the early 1960s by the Czechoslovakian manufacturer [[Jawa Moto]].<ref name=CZ>{{cite web |title=Válka mechaniků: Japonci okopírovali český vynález! |url= https://epochaplus.cz/valka-mechaniku-japonci-okopirovali-cesky-vynalez/ |website=EpochaPlus|language=cs-CZ|date=20 January 2015|last=Kožušník|first=Marek|access-date=27 December 2019}}</ref> Their design was used without permission in the 1965 [[Honda Super Cub|Honda Cub 50]], which resulted in Jawa suing Honda for [[patent infringement]] and Honda agreeing to pay royalties for each motorcycle using the design.<ref name=CZ/>

Other semi-automatic transmissions used in motorcycles include:
* [[Honda]]'s [[Hondamatic]] two-speed transmission fitted with a torque converter (which shares its name with several fully-automatic transmissions), as used in its 1976 [[Honda CB750A|CB750A]], 1977 [[Honda CB400T#CB400A Hawk Hondamatic|CB400A Hawk]], 1978 [[Honda CM400|CM400A]] and 1982 [[Honda CM450A|CM450A]].<ref name="cyclemay1976p69">{{cite journal|title=Cycle magazine |date=May 1976|publisher=Ziff Davis |pages=67–73}}</ref><ref>{{cite web|url= https://www.bennetts.co.uk/bikesocial/news-and-views/news/2020/may/hondamatic-for-the-21st-century |title = Hondamatic for the 21st century}}</ref><ref>{{cite web|url= https://motorcycles.news/en/honda-patent-for-a-semi-automatic-cb1100/ |title=Honda patent for a semi-automatic CB1100|date=27 May 2020}}</ref><ref>{{cite web|url= https://www.visordown.com/news/new-bikes/honda-patent-semi-automatic-system-cb1100 |title = Honda patent semi-automatic system for CB1100}}</ref><ref>{{cite web|url=https://global.honda/heritage/episodes/1968hondamatic.html|title = Honda Global &#124; the Hondamatic Transmission / 1968}}</ref>
* Those in various [[minibike]]s, including the Amstar Nostalgia 49,<ref>{{cite web|url=http://amstarmotor.com/index.php?c=content&a=show&id=599|title = Nostalgia 49-49cc-Motorcycle-Products-Amstar Motor Corporation}}</ref> Honda CRF50F,<ref>{{cite web|url=https://powersports.honda.com/off-road/trail/crf50f/specifications|title=2022 CRF50F SPECIFICATIONS – Honda|website=powersports.honda.com}}</ref> [[Honda Z series|Z series]], and [[Honda ST series (minibike)|ST series]], [[Kawasaki Heavy Industries Motorcycle & Engine|Kawasaki]] KLX-110, KLX-110R,<ref>{{cite web|url=https://www.topspeed.com/motorcycles/motorcycle-reviews/kawasaki/2006-kawasaki-klx-110-ar1968.html|title = 2006 Kawasaki KLX 110 @ Top Speed|date = 7 February 2006}}</ref><ref>{{cite web|url= https://www.topspeed.com/motorcycles/motorcycle-reviews/kawasaki/2012-kawasaki-klx-110-ar121227.html |title = 2012 Kawasaki KLX 110 @ Top Speed|date = 15 December 2011}}</ref><ref>{{cite web|url=https://www.kawasaki.com/en-us/motorcycle/klx/off-road/klx110r|title=Kawasaki KLX110 &#124; Capable Off-Road Dirtbike Motorcycle|website=www.kawasaki.com}}</ref><ref>{{cite web|url=https://www.kawasaki.com/en-us/motorcycle/klr-klx/off-road/klx110r/2021-klx110r?cm_re=MPP-_-KLX%C2%AE110R:MODELS-_-VIEWSPECSDETAILS|title = 2021 Kawasaki KLX®110R &#124; Off-Road Motorcycle &#124; Reliable & Fun}}</ref> and [[Kawasaki KSR110|KSR110]], [[KTM 65 SX]],<ref name="ktm.com" /> [[Suzuki]] DR-Z50,<ref>{{Cite web |title=Suzuki Cycles - Product Lines - Cycles - Products - DR-Z50 - 2021 - DRZ50 |url=http://www.suzukicycles.com/Product%20Lines/Cycles/Products/DR-Z50/2021/DRZ50.aspx |archive-url=https://web.archive.org/web/20210116114955/http://www.suzukicycles.com/Product%20Lines/Cycles/Products/DR-Z50/2021/DRZ50.aspx |archive-date=16 January 2021 |website=suzukicycles.com}}</ref> DR-Z70,<ref>{{cite web|url=https://www.waynecycle.com/inventory/v1/2017/Suzuki/By-Body-Type/Motorcycle/Off-Road/DR-Z70/Base--Waynesboro-Virginia---4483301|title = 2017 Suzuki DR-Z70 Base &#124; Wayne Cycle Shop &#124; Waynesboro, VA}}</ref><ref>{{cite web|url=https://www.topspeed.com/motorcycles/motorcycle-reviews/suzuki/2008-suzuki-dr-z70-ar43196.html|title = 2008 Suzuki DR-Z70 @ Top Speed|date = 11 September 2007}}</ref><ref>{{cite web|url=https://ridecenterusa.com/Showroom/2018/Suzuki/Motorcycle/DR-Z/DR-Z70|title=2018 Suzuki DR-Z 70|website=Ride Center USA}}</ref><ref>{{cite web|url=https://www.cyclechaos.com/wiki/Suzuki_DR-Z_70|title = Suzuki DR-Z 70: Review, history, specs – CycleChaos}}</ref> and [[Suzuki DR-Z125|DR-Z125]],<ref>{{cite web|date=16 February 2007|title=Suzuki DR-Z125 @ Top Speed|url=https://www.topspeed.com/motorcycles/motorcycle-reviews/suzuki/suzuki-dr-z125-ar27430.html}}</ref><ref>{{cite web|url=https://www.motorcycledaily.com/2001/11/12november01entryleveldirtbikes/|title=Kawasaki and Suzuki Introduce Entry Level Four-Stroke Dirt Bikes « MotorcycleDaily.com – Motorcycle News, Editorials, Product Reviews and Bike Reviews}}</ref> SSR SR110TR,<ref>{{cite web|url=http://www.ssrmotorsports.com/store/pitbike/sr110tr.php|title = SSR Motorsports SR110TR}}</ref> and [[Yamaha Motor Company|Yamaha]] TT-R50E.<ref>{{cite web|url=https://www.yamahamotorsports.com/trail-motorcycle/models/tt-r50e|title=2022 Yamaha TT-R50E Trail Motorcycle – Photo Gallery, Video, Specs, Features, Offers, Inventory and more|website=www.yamahamotorsports.com|access-date=19 November 2020|archive-date=27 November 2020|archive-url=https://web.archive.org/web/20201127043400/https://www.yamahamotorsports.com/trail-motorcycle/models/tt-r50e|url-status=dead}}</ref>
* Yamaha used an automatic clutch system called YCCS on motorcycles such as the 2006 [[Yamaha FJR1300]]AE sports-touring.<ref>{{cite web |title=FJR1300AE – YCC-S Electric Shift System |url= http://www.yamaha-motor.com/sport/yccs.aspx |website=yamaha-motor.com |archive-url= https://web.archive.org/web/20120606024741/http://www.yamaha-motor.com/sport/yccs.aspx |archive-date=6 June 2012 |url-status=dead}}</ref> This system can be shifted either with the lever in the traditional position near the left foot or with a switch accessible to the left hand where the clutch lever would go on traditional motorcycles.
* The [[BRP Can-Am Spyder Roadster|Can-Am Spyder Roadster]]'s SE5 and SE6 5-speed and 6-speed transmissions.<ref>Archived at [https://ghostarchive.org/varchive/youtube/20211205/rMHKvDYvjpQ Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20201030003926/https://www.youtube.com/watch?v=rMHKvDYvjpQ&gl=US&hl=en Wayback Machine]{{cbignore}}: {{cite web| url = https://www.youtube.com/watch?v=rMHKvDYvjpQ| title = Can-Am Spyder with Semi-Auto Transmission Walkthrough | website=YouTube}}{{cbignore}}</ref>
* Those in several [[underbone]] motorcycles in the 1970s; the [[Suzuki FR50]], [[Suzuki FR80]], and Yamaha Townmate used 3-speed transmissions with a heel-and-toe gear shift.
* Some high-performance [[sport bike]]s use a trigger-shift system, with a handlebar-mounted trigger, paddle, switch, or button, and an automatically operated clutch.<ref name="flatshifter.com"/><ref>{{cite web|url= https://shiftfx.com/electronic-shift-transmission |title = Electronic Shift Transmission &#124; ShiftFX}}</ref><ref>{{cite web|url= https://www.cycleworld.com/sport-rider/shiftfx-new-take-on-semi-automatic-motorcycle-transmission/|title = ShiftFX: A New Take on the Semi-Automatic Motorcycle Transmission}}</ref>
* Some dirt bikes use this system, which is sometimes referred to as an auto-clutch transmission.<ref name="autowise.com"/><ref name="itstillruns.com"/><ref name="dirtbikehouse.com"/> These include the Honda CRF110F<ref>{{cite web|url= https://powersports.honda.com/off-road/trail/crf110f/specifications|title = 2022 CRF110F Specifications – Honda}}</ref><ref>{{cite web|url= https://powersports.honda.com/off-road/trail/crf110f?year=2020|title = 2022 CRF110F Overview – Honda}}</ref> and Yamaha TT-R110E.<ref name="yamahamotorsports.com"/><ref>{{cite web|url= https://www.yamahamotorsports.com/trail-motorcycle/models/2020/tt-r110e/specifications|title= 2020 Yamaha TT-R110E Trail Motorcycle – Specs, Prices|access-date= 20 November 2020|archive-date= 24 September 2021|archive-url= https://web.archive.org/web/20210924092749/https://www.yamahamotorsports.com/trail-motorcycle/models/2020/tt-r110e/specifications|url-status= dead}}</ref><ref>{{cite web|url=https://www.dirtrider.com/mini-dirt-bikes/|title=Mini Dirt Bikes, 50cc Dirt Bikes|website=Dirt Rider}}</ref> The conventional motorcycle foot shifter is retained, but the manual hand-clutch lever is no longer required.<ref>{{cite web|url=https://www.dirtrider.com/tests/parts-accessories/141_1203_rekluse_exp_auto_clutch_review/|title=Rekluse EXP Auto-Clutch Review|website=Dirt Rider}}</ref><ref name="yamahamotorsports.com"/> Semi-automatic transmissions in dirt bikes may be referred to as "automatic" despite a lack of automatic shifting.<ref>{{cite web|url=https://autowise.com/automatic-dirt-bike/#:~:text=Q%3A%20What%20Is%20A%20Semi,a%20clutch%20isn't%20required.|title=10 Best Automatic Dirt Bike Models|date=17 May 2021|access-date=30 August 2020|archive-date=25 October 2021|archive-url=https://web.archive.org/web/20211025210426/https://autowise.com/automatic-dirt-bike/#:~:text=Q%3A%20What%20Is%20A%20Semi,a%20clutch%20isn't%20required.|url-status=dead}}</ref>

== Usage in motorsports ==
Semi-automatic transmissions in [[racing car]]s are typically operated by shift paddles connected to a designated transmission control unit.

The first [[Formula One]] car to use a semi-automatic transmission was the 1989 [[Ferrari 640]].<ref name="lemans-paddle"/><ref name="ferrarif1">{{cite web |title=Ferrari F1-89 |url= http://formula1.ferrari.com/cars/f1-89 |website=ferrari.com |access-date=2020-02-15 |archive-url= https://web.archive.org/web/20130927170637/http://formula1.ferrari.com/cars/f1-89 |archive-date=2013-09-27}}</ref> It used hydraulic actuators and [[Solenoid|electrical solenoids]] for clutch control and shifting, and was shifted via two paddles mounted behind the steering wheel. Another paddle on the steering wheel controlled the clutch, which was only needed when starting from a standstill.<ref>{{cite web|url=http://www.formula1-dictionary.net/gearbox.html|title = Gearbox}}</ref> The car won its debut race at the [[1989 Brazilian Grand Prix|Brazilian Grand Prix]], but for much of the season suffered from reliability problems.<ref>{{cite web |title=Sequential Sorrow – 1989 Ferrari 640 |url=https://drivetribe.com/p/sequential-sorrow-1989-ferrari-U9zAMNPcScu0UqBZ4NZGPg?iid=Hg2dP1AxS66MagHFEeWL3Q |website=drivetribe.com |access-date=11 August 2020 |language=en |date=1 February 2017}}</ref> Other teams began switching to similar semi-automatic transmissions; the 1991 [[Williams FW14]] was the first to use a [[Sequential manual transmission|sequential]] drum-rotation mechanism (similar to those used in [[motorcycle transmission]]s), which allowed for a more compact design that required only one actuator to rotate the drum and change gears. A further development was made possible by the introduction of [[electronic throttle control]] soon after, which made it possible for the car to automatically rev-match during downshifts.<ref>{{cite web|url=https://www.f1technical.net/features/10705|title=Formula One transmissions|website=www.f1technical.net|date=22 February 2002 }}</ref> By 1993, most teams were using semi-automatic transmissions. The last F1 car fitted with a conventional manual gearbox, the [[Forti FG01]], raced in 1995.<ref name="f1rejects">{{cite web|url= http://www.f1rejects.com/teams/forti/profile.html |title=Forti-Corse – full profile |website=f1rejects.com |access-date=2006-10-29 |url-status=dead |archive-url= https://web.archive.org/web/20071010053720/http://www.f1rejects.com/teams/forti/profile.html |archive-date=10 October 2007 }}</ref>

Following concerns about the potential for Formula One cars to shift gears automatically without any driver input, mandatory software was introduced in 1994<ref>{{cite news|url= https://www.independent.co.uk/sport/motor-racing-mclaren-face-charges-over-automatic-gearbox-benetton-choose-temporary-replacement-for-1447142.html |title=Motor Racing: McLaren face charges over automatic gearbox: Benetton choose a temporary replacement for Schumacher as they prepare to explain Hockenheim fire |work=The Independent |date=6 September 1994 |access-date=17 August 2020}}</ref> that ensured that gear changes only occurred when instructed by the driver. Pre-programmed, computer-controlled, fully-automatic upshifts and downshifts were re-introduced and allowed from [[2001 Formula One World Championship|2001]], and were permitted from that year's [[2001 Spanish Grand Prix|Spanish Grand Prix]], but were banned again in [[2004 Formula One World Championship|2004]].<ref>{{cite web|url= https://www.autosport.com/f1/news/atlasf1-10307/traction-control-to-stay-in-f1-in-2004 |title=Traction Control to Stay in F1 in 2004 – F1 – Autosport|website=autosport.com|date=2 May 2003 |access-date=12 November 2020}}</ref><ref>{{cite web|url= http://autoweek.com/news/a2093556/fia-makes-massive-changes-f1-several-technological-enhancements-banned/ |title=FIA makes massive changes to F1; several technological enhancements banned|date=14 January 2003|website=Autoweek|access-date=12 November 2020}}</ref><ref>{{cite web|url= https://www.espn.com/racing/news/story?id=1741040 |title=Knutson: F1 shifting gears, literally|date=22 February 2004|website=ESPN.com|access-date=12 November 2020}}</ref><ref>{{cite web|url= https://au.motorsport.com/f1/news/less-electronics-will-make-life-interesting/1109290/ |title=Less electronics will make life interesting|website=au.motorsport.com|date=4 February 2004 |access-date=12 November 2020}}</ref><ref>{{cite web|url=https://badgergp.com/montmelo-memories-2001-spanish-grand-prix/|title=Montmelo Memories: 2001 Spanish Grand Prix|first=Charlie|last=Eustice|date=8 May 2015|website=badgergp.com|access-date=4 December 2020|archive-date=25 October 2021|archive-url=https://web.archive.org/web/20211025231630/https://badgergp.com/montmelo-memories-2001-spanish-grand-prix/|url-status=dead}}</ref><ref>{{cite web|url=https://www.motorsport.com/f1/news/teams-come-to-grips-with-return-of-traction-control/62785/|title=Teams come to grips with return of traction control|website=motorsport.com|access-date=4 December 2020}}{{Dead link|date=June 2022 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{cite web|url= http://www.grandprix.com//news/traction-control-returns-but-its-not-quite-as-simple-as-that.html |title=Traction control returns; but it's not quite as simple as that |website=grandprix.com|access-date=4 December 2020}}</ref><ref>{{cite web|url= https://www.crash.net/f1/news/38390/1/preview-spanish-grand-prix-2001 |title=Preview: Spanish Grand Prix 2001 |date=24 April 2001|website=Crash.net|access-date=4 December 2020}}</ref> Buttons on the steering wheel to shift directly to a particular gear (instead of having to shift sequentially using the paddles) are permitted.{{Citation needed|date=October 2021}} The 2005 [[Minardi PS05]], [[Renault R25]], and [[Williams FW27]] were the last Formula 1 cars to use a 6-speed gearbox before the switch to a mandatory 7-speed gearbox for the [[2006 Formula One World Championship|2006 season]]. Since [[2014 Formula One World Championship|2014 season]], Formula 1 cars currently use mandatory 8-speed paddle-shift gearboxes.

The now-defunct [[Championship Auto Racing Teams|CART]] [[Champ Car World Series|Champ Car Series]] switched from a lever-shift sequential system to a 7-speed paddle-shift system for the [[2007 Champ Car season|2007 season]]. This transmission was introduced with the new-for-2007 [[Panoz DP01]] chassis.

The rival [[IndyCar Series]] introduced their 6-speed semi-automatic paddle-shift system for the [[2008 IndyCar Series|2008 season]], also replacing the previous lever-shifted sequential transmission, introduced with the [[Dallara|Dallara IR-05]] chassis for 2008.<ref>{{cite web|url=https://www.autosport.com/indycar/news/64891/irl-confirms-technical-tweaks|title = IRL confirms technical tweaks}}</ref> IndyCars currently use the [[Xtrac Limited|Xtrac]] P1011 sequential transmission, which uses a semi-automatic paddle shift system supplied by Mega-Line called AGS (Assisted Gearshift System). AGS uses a pneumatic gearshift and clutch actuator controlled by an internal transmission control unit.<ref>{{cite web|url=https://www.xtrac.com/product/p1011-indycar-series-gearbox/|title = Xtrac – P1011 INDYCAR SERIES GEARBOX}}</ref><ref>{{cite web|url=https://www.xtrac.com/product/assisted-gearchange-system/|title=Xtrac – ASSISTED GEARCHANGE SYSTEM}}</ref><ref>{{cite web|url=https://www.indycar.com/Fan-Info/INDYCAR-101/The-Car-Dallara/IndyCar-Series-Chassis-Specifications|title=NTT INDYCAR SERIES Car Specifications|access-date=12 August 2020|archive-date=25 July 2020|archive-url=https://web.archive.org/web/20200725080159/https://www.indycar.com/Fan-Info/INDYCAR-101/The-Car-Dallara/IndyCar-Series-Chassis-Specifications|url-status=dead}}</ref><ref>{{cite web|url=http://mega-line.info/index.php/en/products/compressor?productitem=21|title=MEGA-Line RACING ELECTRONIC &#124; Paddle Shift &#124; AGS &#124; E-Schaltwalze &#124; Pitstop Equipment – GCU / Compressor}}</ref><ref>{{cite web|url=http://www.mega-line.de/index.php/en/company/references|title = MEGA-Line RACING ELECTRONIC &#124; Paddle Shift &#124; AGS &#124; E-Schaltwalze &#124; Pitstop Equipment – Credentials}}</ref>

Both the [[FIA Formula 2 Championship|FIA Formula 2]] and [[FIA Formula 3 Championship|Formula 3 Championships]] currently use 6-speed sequential gearboxes with electro-hydraulic operation via shift paddles. Manual control of the multi-plate clutch systems via a lever behind the steering wheel is used to launch the cars.

[[Deutsche Tourenwagen Masters|DTM]] currently uses a [[Hewland]] DTT-200 6-speed sequential transmission with steering-wheel-mounted shift paddles, which was introduced for the [[2012 Deutsche Tourenwagen Masters|2012 season]] with the new rule change. This new system replaced the older lever-shifted sequential transmission, which had been used for the previous 12 seasons (since [[2000 Deutsche Tourenwagen Masters|2000]]).

== Usage in other vehicles ==
{{see also|Truck#Drivetrain}}
Other notable uses for semi-automatic transmissions include:
* During the 1940s to 1960s, many small diesel [[shunting locomotive]]s used [[Epicyclic gearing|epicyclic]] semi-automatic transmissions. For example, the [[British Rail Class 03]] and [[British Rail Class 04]] used the [[Wilson-Drewry]] CA5 R7 transmission.<ref name=BMRG1>{{cite web| url= http://www.barrowmoremrg.co.uk/BRBDocuments/Locos/Book_No_120_web.pdf| title=Vehicle Diagram Book No. 120 for shunting diesel locomotives| publisher=BRB Residuary |website=barrowmoremrg.co.uk| access-date=2 July 2021}}</ref>
* The Sinclair S.S.S. Powerflow, used from the 1950s to the early 1960s in Huwood-Hudswell diesel mining locomotives, the [[British Rail Class D2/7]] and the [[British Rail Class D2/12]].<ref name="dmm1">{{cite web|author=Durham Mining Museum |url=http://www.dmm.org.uk/colleng/4805-01.htm |title=Durham Mining Museum – Colliery Engineering |publisher=Dmm.org.uk |date=17 December 2012 |access-date=2014-07-18}}</ref> The Powerflow design is of the layshaft type with constant-mesh gears and [[dog clutch]] engagement, allowing it to provide seamless power delivery during upshifts. This transmission was also used in some road vehicles.<ref>{{cite journal|url= http://archive.commercialmotor.com/article/16th-august-1946/43/vulcan-sinclair-fluidrive-makes-headway | archive-url = https://web.archive.org/web/20170906035333/http://archive.commercialmotor.com/article/16th-august-1946/43/vulcan-sinclair-fluidrive-makes-headway | archive-date = 6 September 2017 | page = 69 | title=Vulcan-Sinclair Fluidrive Makes Headway | date = 16 August 1946 | journal = The Commercial Motor }}</ref>
* The [[Self-Changing Gears#Bus applications|Self-Changing Gears Pneumocyclic]], an epicyclic transmission built in the United Kingdom from the 1960s to the 1980s. Using a similar design to the company's previous [[preselector gearbox]]es, the Pneumocyclic transmission was used in several buses, such as the [[Leyland Leopard]], [[Leyland Panther|Panther]], and [[Leyland Tiger|Tiger]].<ref>{{cite web |title=Leyland Make "Air" Gearbox |url= http://archive.commercialmotor.com/article/5th-march-1954/47/leyland-make-air-gearbox |website=commercialmotor.com |access-date=14 August 2020}}</ref><ref>{{cite web |title=Transmissions: a period of change |url= http://archive.commercialmotor.com/article/6th-december-1974/47/transmissions-a-period-of-change |website=commercialmotor.com |access-date=14 August 2020}}</ref> It was also fitted to several thousand British diesel [[railcar]]s during this time.{{citation needed|date=August 2020}}
* [[All-terrain vehicle]]s, such as the Honda ATC185, [[Honda ATC200]],<ref>{{cite web|url=https://hondanews.com/en-US/releases/honda-atv-model-history-timeline-1970-present?l=en-US&mode=print|title = Honda ATV Model History Timeline, 1970–Present|date = 22 November 2004}}</ref> Honda TRX90X and TRX250X (Honda SportClutch),<ref>{{cite web|url=https://powersports.honda.com/atv/sport|title=Sport – Honda|website=powersports.honda.com}}</ref> [[Suzuki LT125D|Suzuki LT125D Quadrunner]] (also known as the Suzuki QuadRunner 125), [[Suzuki LT 230]], [[Suzuki Eiger 400]], Yamaha Big Bear 250,<ref>{{cite web|url=https://www.totalmotorcycle.com/ATV-Quad/2009ATVmodels/2009-Yamaha-BigBear250/|title=2009 Yamaha Big Bear 250|website=Total Motorcycle}}</ref><ref>{{cite web|url=https://www.atvstyle.com/yamaha-big-bear-specs-and-reviews|title = Yamaha Big Bear Specs, Top Speed, HP, Etc|date = 9 January 2021}}</ref> 350,<ref>Archived at [https://ghostarchive.org/varchive/youtube/20211205/k5Udmi6Ozsk Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20201207124909/https://www.youtube.com/watch?v=k5Udmi6Ozsk Wayback Machine]{{cbignore}}: {{cite web| url = https://www.youtube.com/watch?v=k5Udmi6Ozsk| title = 1999 Yamaha Big Bear 350 4x4 – Testing Classic ATVs | website=YouTube}}{{cbignore}}</ref><ref>{{cite web|url=https://global.yamaha-motor.com/showroom/cp/collection/atv_yfm350bigbear/|title = 1996 YFM350 Big Bear – Communication Plaza &#124; Yamaha Motor Co., Ltd}}</ref> and 400,<ref>{{cite web|url=https://www.atv.com/specs/yamaha/utility/2004/big-bear/400-4x4/detail.html|title = 2004 Yamaha Big Bear 400 4x4| date=24 October 2022 }}</ref> Yamaha Grizzly 80,<ref>{{cite web|url= https://www.atv.com/specs/yamaha/youth/2006/grizzly/80.html|title = 2006 Yamaha Grizzly 80| date=24 October 2022 }}</ref> Yamaha Grizzly 700, Yamaha Raptor 80,<ref>{{cite web|url=https://www.atv.com/specs/yamaha/youth/2004/raptor/80/detail.html|title = 2004 Yamaha Raptor 80| date=24 October 2022 }}</ref> Yamaha YFB250 Timberwolf,<ref>{{cite web|url=https://global.yamaha-motor.com/showroom/cp/collection/atv_yfb250timberwolf/|title = 1996 YFB250 TIMBERWOLF – Communication Plaza &#124; Yamaha Motor}}</ref> the Yamaha Moto-4 ATV range,<ref>{{cite web|date=7 August 2020|title=Yamaha Moto 4 – Complete Review and Specs|url=https://offroadingpro.com/yamaha-moto-4/}}</ref> and the Yamaha Tri-Moto range.<ref>{{cite web|url=https://global.yamaha-motor.com/showroom/cp/collection/atv_yt125tri-moto/|title = 1979 YT125 TRI-MOTO – Communication Plaza &#124; Yamaha Motor}}</ref><ref>{{cite web|url=https://itstillruns.com/yamaha-yt125-specs-7527557.html|title = Yamaha YT125 Specs}}</ref>
**The Honda Electric Shift Program is used in ATVs such as the 1998 Honda TRX450FE (also called the Foreman 450ES ESP) and first-generation [[Honda Rincon]]. Shifting is accomplished by pressing one of the two gear selector arrows on the left handlebar, which activates an electric shifting system.

==See also==
{{Transmission types}}
* [[Dual-clutch transmission]] (DCT)
* [[Manumatic]]
* [[Saxomat]]
* [[Shift time]]

{{clear}}

== References ==
{{Reflist|30em}}

{{Powertrain|state=expanded}}

{{DEFAULTSORT:Semi-automatic transmission}}
[[Category:Automotive transmission technologies]]
[[Category:Automobile transmissions]]
[[Category:Motorcycle transmissions]]
[[Category:Mechanical power control]]