Automatic Transmission in Automobiles (Cars)

How Automatic Transmissions Work

History


Many of the mechanisms and technologies that are used in the modern automatic transmission system  were already in use in manual transmissions. 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 in 1937.

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. With planetary gears and a conventional friction clutch, these transmissions allowed easier shifting and required less driving skill. Cadillac and Oldsmobile issued models with  automatic transmission through 1939. Buick used it  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 was developed by GM engineer, Earl Thompson,  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.  Other auto manufacturers purchased and used the Hydro-Matic. These included:

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


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.

Mercedes introduced their first automatic in 1962. Rolls Royce's 1955 intro was with GM's Hydro-Matic. Daimler 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      configurations

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

     Ignition lock coupling - anti-theft feature


In the late 1980s, use of computers in cars started. and resulted in 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 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

Transmission research and development is currently leaning toward Automated Manual Transmission technologies. Suzuki has come out with successful technology and is using it in a Indian model Celerio.


http://www.diablotransmissions.com/history_automatic_transmission.html
http://4thefirsttime.blogspot.in/2007/06/1939-first-american-cars-with-automatic.html