Editing Automatic transmission (section)

===History===
{{globalize|section|United States|date=November 2020}}

====1904–1939: Predecessors to the hydraulic automatic====
The 1904 Sturtevant "horseless carriage gearbox" is often considered to be the first automatic transmission for motor vehicles.<ref>{{cite web |title=The American Automobile 1861-1929 Chapter 2 |url=http://www.earlyamericanautomobiles.com/americanautomobiles2.htm |website=www.earlyamericanautomobiles.com |access-date=1 November 2020 |archive-date=22 February 2020 |archive-url=https://web.archive.org/web/20200222192744/http://www.earlyamericanautomobiles.com/americanautomobiles2.htm |url-status=dead}}</ref><ref>{{cite web |title=The Pros and Cons of Automatic Transmissions |url=https://stevesimports.com/blog/the-pros-and-cons-of-automatic-transmissions/ |website=www.stevesimports.com |access-date=1 November 2020 |language=en |date=30 September 2019}}</ref> At higher engine speeds, high gear was engaged. As the vehicle slowed down and engine speed decreased, the gearbox would shift back to low. However, the transmission was prone to sudden failure, due to the transmission being unable to withstand forces from the abrupt gear changes.

The adoption of planetary gearsets was a significant advance towards the modern automatic transmission. One of the first transmissions to use this design was the manual transmission fitted to the 1901–1904 [[Wilson-Pilcher]] automobile.<ref name="Automotor">{{cite news |title=The Wilson-Pilcher Petrol Cars |work=The Automotor Journal |date=16 April 1904 |pages=463–468, also pp. 492–496, and pp. 519–521}}</ref> This transmission was built in the United Kingdom and used two epicyclic gears to provide four gear ratios. A foot clutch was used for standing starts, gear selection was using a hand lever, helical gears were used (to reduce noise) and the gears used a constant-mesh design. A planetary gearset was also used in the 1908 [[Ford Model T]], which was fitted with a two-speed manual transmission (without helical gears).

An early patent for the automatic transmission was granted to Canadian inventor Alfred Horner Munro of Regina in 1923.<ref>{{cite web |last1=Government of Canada |title=Canadian Patent Database |url=http://brevets-patents.ic.gc.ca/opic-cipo/cpd/eng/patent/235757/summary.html |website=www.brevets-patents.ic.gc.ca |access-date=22 November 2020 |language=en |date=15 June 2015}}</ref> Being a steam engineer, Munro designed his device to use [[compressed air]] rather than [[hydraulic fluid]], and so it lacked power and never found commercial application.<ref>{{cite web|last1=Warwick|first1=Alan|title=Who Invented the Automatic Gearbox|date=9 April 2013 |url=http://www.nwtgearboxes.co.uk/who-invented-the-automatic-gearbox|publisher=North West Transmissions|access-date=11 October 2014}}</ref>

In 1923, a patent was approved in the United States describing the operation of a transmission where the manual shifting of gears and manual operation of a clutch was eliminated. This patent was submitted by Henry R. Hoffman from Chicago and was titled: ''Automatic Gear Shift and Speed Control''. The patent described the workings of such a transmission as "...having a series of clutches disposed intermediate the engine shaft and the differential shaft and in which the clutches are arranged to selectively engage and drive the differential shaft dependent upon the speed at which the differential shaft rotates". However, it would be over a decade later until automatic transmissions were produced in significant quantities. In the meantime, several European and British manufacturers would use [[preselector gearbox]]es, a form of manual transmission which removed the reliance on the driver's skill to achieve smooth gear shifts.

The first automatic transmission using hydraulic fluid was developed in 1932 by two Brazilian engineers, José Braz Araripe and Fernando Lehly Lemos.<ref>{{Cite web|date=2019-08-30|title=Top 10 All-Time Auto Inventions|url=https://www.inventorsdigest.com/articles/top-10-all-time-auto-inventions/|access-date=2021-03-29|website=Inventors Digest|language=en-US}}</ref><ref name="hearst"/>

The evolution towards mass-produced automatic transmissions continued with the 1933–1935 [[REO Motor Car Company]] ''Self-Shifter'' semi-automatic transmission,<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=www.hagerty.com |access-date=9 August 2020 |date=8 August 2019}}</ref> which automatically shifted between two forward gears in the "Forward" mode (or between two shorter gear ratios in the "Emergency low" mode). Driver involvement was still required during normal driving, since standing starts required the driver to use the clutch pedal.<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> This was followed in 1937 by the [[Oldsmobile]] ''Automatic Safety Transmission''. Similar in operation to the REO ''Self-Shifter'', the ''Automatic Safety Transmission'' shifted automatically between the two gear ratios available in the "Low" and "High" ranges and the clutch pedal was required for standing starts. It used a planetary gearset.<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=www.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=www.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=www.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 Chrysler ''[[Fluid Drive]]'', introduced in 1939, was an optional addition to manual transmissions where a fluid coupling (similar to a torque-convertor, but without the torque multiplication) was added, to avoid the need to operate a manual clutch.<ref>{{cite web |title=The Fluid Drive torque converter |url=https://www.allpar.com/mopar/fluidrive.html |website=www.allpar.com |access-date=3 November 2020}}</ref><ref>{{cite web |title=Video: An Introduction to Chrysler Fluid Drive |url=https://www.macsmotorcitygarage.com/video-an-introduction-to-chrysler-fluid-drive/ |website=www.macsmotorcitygarage.com |access-date=3 November 2020 |date=24 October 2017}}</ref>

====1939–1964: Early hydraulic automatics====
The General Motors [[Hydra-Matic]] became the first mass-produced automatic transmission following its introduction in 1939 (1940 model year). Available as an option in cars such as the [[Oldsmobile Series 60#1939–1940|Oldsmobile Series 60]] and [[Cadillac Sixty Special#1938–1941|Cadillac Sixty Special]], the Hydra-Matic combined a [[fluid coupling]] with three [[hydraulics|hydraulically controlled]] planetary gearsets to produce four forward speeds plus reverse. The transmission was sensitive to engine throttle position and road speed, producing fully automatic up- and down-shifting that varied according to operating conditions. Features of the Hydra-Matic included a wide spread of ratios (allowing both good acceleration in first gear and cruising at low engine speed in top gear) and the fluid coupling handling only a portion of the engine's torque in the top two gears (increasing fuel economy in those gears, similar to a [[Lock-up clutch|lock-up]] torque converter). Use of the Hydra-Matic spread to other General Motors brands and then to other manufacturers starting 1948 including [[Hudson Motor Car Company|Hudson]], [[Lincoln Motor Company|Lincoln]], [[Kaiser Motors|Kaiser]], [[Nash Motors|Nash]], [[Holden]] (Australia), as well as [[Rolls-Royce Motor Cars|Rolls-Royce]] and [[Bentley]] licensing production in the UK and providing the transmission to [[Jensen Motors]], [[Armstrong Siddeley]] and other UK manufacturers.<ref>{{cite web | url=https://ateupwithmotor.com/terms-technology-definitions/rolls-royce-automatic-gearbox | title=Don't Call It Hydra-Matic: The Rolls-Royce and Bentley Automatic Gearbox < Ate up with Motor | date=4 September 2022 }}</ref> During World War II, the Hydra-Matic was used in some military vehicles.

The first automatic transmission to use a torque converter (instead of a fluid coupling) was the Buick [[Dynaflow]], which was introduced for the 1948 model year. In normal driving, the Dynaflow used only the top gear, relying on the torque multiplication of the torque convertor at lower speeds. The Dynaflow was followed by the Packard [[Ultramatic]] in mid-1949 and the Chevrolet [[Powerglide]] for the 1950 model year. Each of these transmissions had only two forward speeds, relying on the converter for additional torque multiplication. In the early 1950s, [[BorgWarner]] developed a series of three-speed torque converter automatics for car manufacturers such as American Motors, Ford and Studebaker. [[Chrysler]] was late in developing its own true automatic, introducing the two-speed torque converter [[PowerFlite]] in 1953, and the three-speed [[TorqueFlite]] in 1956. The latter was the first to utilize the Simpson compound planetary gearset.

In 1956, the General Motors Hydra-Matic (which still used a fluid coupling) was redesigned based around the use of two fluid couplings to provide smoother shifts. This transmission was called the ''Controlled Coupling Hydra-Matic'', or "Jetaway" transmission. The original Hydra-Matic remained in production until the mid-1960s at GM, with the licensed Rolls-Royce Automatic transmission soldiering on until 1978 on the [[Rolls-Royce Phantom VI]]. In 1964, General Motors released a new transmission, the [[Turbo Hydramatic]], a three-speed transmission which used a torque convertor. The Turbo Hydramatic was among the first to have the basic gear selections (''park'', ''reverse'', ''neutral'', ''drive'', ''low'') which became the standard gear selection used for several decades.

====1965–present: increased ratio count and electronics====
By the late 1960s, most of the fluid-coupling two-speed and four-speed transmissions had disappeared in favor of three-speed units with torque converters. Also around this time, [[whale oil]] was removed from the automatic transmission fluid.<ref>{{cite web|url=http://www.machinerylubrication.com/article_detail.asp?articleid=392 |title=Almost Burned |website=www.machinerylubrication.com |archive-url=https://web.archive.org/web/20070927082224/http://www.machinerylubrication.com/article_detail.asp?articleid=392 |archive-date=27 September 2007}}</ref> During the 1980s, automatic transmissions with four gear ratios became increasingly common,<ref>{{cite web |title=U.S. Patent 5370589 |url=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=1&p=1&f=G&l=50&d=PTXT&S1=5370589.PN.&OS=pn%2F5370589&RS=PN%2F5370589 |website=www.patft.uspto.gov |archive-url=https://web.archive.org/web/20130514181727/http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=1&p=1&f=G&l=50&d=PTXT&S1=5370589.PN.&OS=pn%2F5370589&RS=PN%2F5370589 |archive-date=14 May 2013 |url-status=dead}}</ref> and many were equipped with lock-up torque convertors in order to improve fuel economy.

[[Electronics]] began to be more commonly used to control the transmission, replacing mechanical control methods such as spring-loaded valves in the valve body. Most systems use [[solenoid]]s which are controlled by either the [[engine control unit]], or a separate [[transmission control unit]]. This allows for more precise control of shift points, shift quality, lower shift times and manual control.

The first five-speed automatic was the [[ZF_5HP_transmission|ZF 5HP18 transmission]], debuting in 1991 on various [[BMW]] models. The first six-speed automatic was the [[ZF 6HP26 transmission]], which debuted in the 2002 [[BMW 7 Series (E65)]]. The first seven-speed automatic was the [[Mercedes-Benz 7G-Tronic transmission]], which debuted a year later. In 2007, the first eight-speed transmission to reach production was the [[Toyota A transmission#AA80E|Toyota AA80E transmission]]. The first nine-speed and ten-speed transmissions were the 2013 [[ZF 9HP transmission]] and 2017 ''Toyota Direct Shift-10A'' (used in the [[Lexus LC]]) respectively.