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Automatic Transmission
and Evolution Time Line

Then (1940)

Now (2014)
transmission advancements 

1937: General Motors introduced the first semi-automatic transmission, which they called and promoted as the “Automatic Safety Transmission” or AST for short.  The AST had four forward speeds and used a planetary gear set and a friction clutch.  Cadillac and Oldsmobile used the AST is some models from 1937 through 1939 and Buick offered it in the 1938 Buick Special for a limited time.  In short, the Automatic Safety Transmission was pretty much labeled a failure from the very beginning.  Besides being unreliable, the AST was a $80 option but cost Oldsmobile $140 per unit to manufacturer.  Vehicle buyers at the time were also unreceptive to the AST, which made the decision to discontinue the transmission after just 2 short years quite easy.

Automatic Safety Transmission 

Oldsmobile's Automatic Safety Transmission was promoted as the New Driving Sensation, but lasted on two years in production.

1940: Although unsuccessful as the Automatic Safety Transmission, a newly designed version of the AST by General Motors called the Hydra-Matic would become legendary.  This fully automatic transmission (the first transmission requiring no clutch pedal) debuted as a $57 option in the 1940 Oldsmobile.  The Hydra-Matic was the world's first mass-produced and commercially used fully automatic transmission.

Just as Oldsmobile’s advertising had overstated the capabilities and reliability of the Automatic Safety Transmission, advertisements promoting the new Hydra-Matic transmission were equally as bold.  One advertisement claimed that the Hydra-Matic transmission represented the most significant technological advancement since the electric starter.  Another advertisement claimed that the Hydra-Matic transmission increased fuel economy by 10 – 15% over a standard transmission.  But, this time it was all true.  The Hydra-Matic fully automatic transmission was truly groundbreaking - it established the foundation from which future automatic transmissions would be designed and built.

Hydra-Matic Automatic Transmission

1941: Being the first true automatic transmission (no clutch pedal) consumers ordered the $57 Hydra-Matic transmission option in impressive numbers.  By 1941, roughly 40% of all Oldsmobile passenger cars and 30% of all Cadillac passenger cars sold in the U.S. were ordered with Hydra-Matic transmissions.

1942: In 1942, when automobile manufacturing plants stopped manufacturing vehicles to build war machinery, more than 200,000 Hydra-Matic automatic transmissions had been sold.

arrow The Hydra-Matic transmission did not have Park.  Instead, a parking pawl engaged when the transmission was shifted into Reverse and the engine was shut off, which kept the vehicle from rolling when it was parked.

War Time: With automobile manufacturing plants building tanks instead of cars, use of the Hydra-Matic transmission in military applications (primarily tanks), without any major changes to the transmission solidified the Hydra-Matic as being one of the most significant and important developments in automotive history.

Post War: During the post war boom, the demand for vehicles with automatic transmissions continued to grow despite the increased cost.  By late 1948, 86% of new Oldsmobile passenger vehicles sold were equipped with the optional (and more expensive) Hydra-Matic transmission.  During this same year, sales of Hydra-Matic equipped Cadillac passenger vehicles had reached 95%.  For Cadillac, the Hydra-Matic was a $175 option.  By this time, the Pontiac division of General Motors offered the Hydra-Matic tranny as a $150 option, which three out of four buyers chose.

Even the loudest critics of the automatic transmission could not ignore the facts; the commercial success of the Hydra-Matic automatic transmission in passenger vehicles mandated that all car manufacturers offer an automatic transmission as an option to the standard "manual" transmission or risk going out of business.


With the introduction of new automatic transmissions in the late 40s and early 50s, the automatic transmission wars between the big automakers was underway.

1948, 1949 and 1950: In 1948, the first fully automatic transmission using a torque converter was introduced by Buick.  Buick called their transmission the "Dynaflow".  Packard and Chevrolet promptly followed Buick with their own transmission designs, both of which incorporated the use of a torque converter.  Packard introduced the Ultramatic fully automatic transmission in 1949 and Chevrolet introduced the Powerglide fully automatic transmission in 1950.  While these transmissions had only two forward speeds, the use of a torque converter enabled additional torque multipliers, effectively increasing the forward gear ratios and forward speeds.

Early 1950s: The first three-speed automatic transmissions using torque converters were developed by Borg Warner in the early 1950s for a number of automakers including Ford and Studebaker. In 1953, Chrysler introduced the two-speed torque converter driven PowerFlite automatic transmission. Other vehicle manufacturers, including Rolls Royce, Hudson, Bentley and even Lincoln (a Ford Motor Company division) purchased Hydra-Matic transmissions from General Motors to fill their needs.

keep reading Automatic Transmission Evolution: Late 1950s and Beyond 
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