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   Concord, CA 94520
   Phone: 925-685-3575








History of the Automotive Automatic Transmission
by Preston Taylor

Surprisingly, many of the mechanisms and technologies that make the modern automatic transmission operate were already in use during the rather lengthy genesis that manual transmissions went through.
Transmission bands and planetary gears were used in the manual transmission for the Ford Model T and Model K (1906). Fluid coupling was used by General Motors as early as 1937. 

Even more surprising, these technologies were first developed in the early 1900s in Germany for use in marine applications.

Semi-automatic transmissions appeared in a major automotive brand in 1937. General Motors dubbed these "the Automatic Safety Transmission"(AST). With planetary gears and a conventional friction clutch, these transmissions allowed easier shifting and required less driving skill. Cadillac and Oldsmobile issued models with AST through 1939. Buick used the AST only in 1938. The AST never inspired the driving public and was not supported by large sales numbers.

The 1948 Oldsmobile was the first model to use a true automatic transmission. The Hyrdo-Matic, developed by GM engineer, Earl Thompson, was advertised as "The greatest advance since the self-starter." The Hydro-Matic went through continual upgrading and refinements through 1955. But, the basic design and theory used were consistent throughout its remarkably long life span. Over the years the Hydro-Matic was used in many military applications including the M5 Stuart tank and the M24 Chaffee light tank. Other auto manufacturers purchased and used the Hydro-Matic. These included:

Hudson Nash Rambler
Frazer Nash Kaiser
Willys Lincoln
Rolls-Royce Bentley

Even into the 1990s, the Hydro-Matic was used, in modified versions, for drag racing and hotrod applications. One company in particular made the "B&M Hydro" a mainstay of performance enthusiasts for decades, and in cooperation with Andy Granatelli, made the Hydro-Matic the only automatic transmission to ever be used in Indy Car racing.

General Motors replaced the Hydro-Matic in 1956 with the Jetaway. The "Jet" was not a roaring success and quickly gave way to the Turbo Hydromatic.

Chrysler's Fluid Drive was introduced in 1939, but this was really a manual transmission that used a fluid coupling to make shifting easier. Chrysler first produced a semi-automatic transmission in 1942 and was late in developing their own true automatic transmission, introducing the two-speed PowerFlite in 1954.

BorgWarner engineered the first automatic transmission used by Ford, introduced in 1950.

Americans lead the way in deploying automatics. Mercedes introduced their first automatic in 1962. Rolls Royce's 1955 intro was with GM's Hydro-Matic. Daimler (then owned by Jaguar) first used a BorgWarner 4-speed in 1962.

Through the 1980s changes and advances occurred quickly. Special features seemed to be the primary focus of transmission designers.

Options included:

     Manual-or-automatic shifting - allowed
     drivers to take control of the shifting when
     they wished

     Push-button shifting - a Chrysler Torqueflite
     innovation that used a two-cable mechanism

     Edsel's Teletouch shifting - buttons in the
     middle of the steering wheel that operated
     an electric shift motor

     Economy-performance settings - the
     driver could reset with the push of a button

     Over-drive in 3, 4, and 4-plus-overdrive

     Hill-hold - prevented the vehicle from
     rolling backwards at idle on an upgrade

     Ignition lock coupling - anti-theft feature

Editor's note:
The following is hardly a history chapter. Rather, it is a quick overview of transmission technology since the 1980s. Please check back at a later date to view additional history entries. Last update: November 2, 2006

In the late 1980s, as onboard computers became prevalent, came the introduction of electronic controls for automatic transmissions. Solenoids and sensors integrate with multiple onboard computers to control shifting and gear ratio in any imaginable scenario.

Honda's Hondamatic, originally a two-speed, was reborn in 1979 as the H3 three-speed. This transmission is unique in that it is an automatic that does not use planetary gears. Gears slide on parallel shafts. The Hondamatic is similar neither to other automatic transmissions nor to manual transmissions.

Five-speed, six-speed, seven, and even eight-speed transmissions are currently being used in automobiles. Such technologies are being tested and deployed in an effort to improve economy and efficiency.

CVTs provide continuous torque at engine peek-performance speeds

In a return-to-roots sort of trend, transmission research and development is currently leaning toward Automated Manual Transmission technologies.

Please check back at a later date to view additional history entries. Last update: November 2, 2006.

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