A Brief History of the Automatic Transmission

No more missed shift gates. No engine lugging or racing. No torn-stocking, high-heel clutch-pedaling dramas. None of that. Just press the gas and go.

 

The introduction of the automatic transmission did this by offering a “no-muss, no-fuss” form of shifting. The earliest automobiles offered only manual transmissions, which were similar in principle to today’s stick-shift vehicles. These cars sported two forward gears and one reverse, coupled to the engine via a series of pedals. But as cars grew larger and traffic got worse, engineers began searching for a way to have the car “automatically” shift from one gear to another. Designers spent decades perfecting the modern automatic transmission. Here we offer a brief introduction and overview of the history of the automatic transmission.

The First Automatic Transmissions

The first automatic transmission was invented in 1921 by a Canadian steam engineer, Alfred Horner Munro. Munro designed his device to use compressed air rather than hydraulic fluid so it lacked power and never became sold commercially. General Motors then developed the first automatic transmission using hydraulic fluid in the 1930’s, and introduced the “Hydra-Matic” transmission in 1940.

The 1948 Oldsmobile was the first model to use a true automatic transmission. The Hyrda-Matic, developed by GM engineer, Earl Thompson, was advertised as: “The greatest advance since the self-starter.” The Hydra-Matic went through continual upgrading and refinements through 1955, but the basic design and theory used were consistent throughout its remarkably long life span. General Motors replaced the Hydra-Matic in 1956 with the Jetaway. The “Jet” was not a roaring success and quickly gave way to the Turbo Hydra-Matic in 1969.

The Hydra-Matic Transmission

The original Hydra-Matic transmission was one of the most important innovations in the history of the automobile. It wasn’t the first automatic transmission, but it was the first one that really worked and its resounding commercial success paved the way for every subsequent autoshifter.

The technology came along at an opportune time in history as North America was abundant with victory from World War II and building up steam for the post-war boom. Scads of babies and cars were produced (not necessarily in that order). Into those cars they dropped thousands of automatic transmissions. With its simplicity and ease of use, the automatic transmission offered up the automobile to the masses, fulfilling the promise of President Hoover, whom a generation earlier had promised “a car in every garage and a chicken in every pot.” At the very least it widened the perspective of an increasingly mobile workforce, fed the flow of migration to the suburbs, and welcomed women back into the economy following the war effort.

The most significant changes/improvements in automatic transmission design to date are the number of forward gears transmissions now have and the switch from mechanically controlled to electronically controlled transmission operations. Mechanically controlled automatic transmissions have reached their limit in terms of future improvements while electronically (or computer) controlled automatic gearboxes have only touched the surface of the possibilities.

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