Automatic Transmissions- A Brief History
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The First Automatic Transmission
The inventor of the first automatic transmission (AT) was: Alfred Horner Munro. Alfred Horner Munro was Born in Regina, Saskatchewan’s, Canada. He invented the first AT in 1921. It was called “Automatic Safety Transmission” (AST). The AST was patented in 1923. Alfred Horner Munro was a Canadian steam engineer by trade. He designed it using air pressure rather than hydraulic fluid. This, however, created a huge lack of power. It did have 4 forward gear ratios, but no reverse or parking gear. General Motors sold the AST in three of their models between the years of 1937-1938; the Oldsmobile, Cadillac, and Buick as an upgrade option.
The Invention of the Hydraulic Transmission
The inventors of the first hydraulic transmission were two Brazilians engineers: José Braz Araripe and Fernando Lehly Lemos.
1940 Oldsmobile with Hydra-Matic Transmission
General Motors bought the prototype and plans and introduced the first hydraulic transmission called the Hydra-Matic. They started production on the Hydra-Matic in 1940 to be sold as an option in the Oldsmobile line. This was the first AT to be mass-produced. This forever changed the automotive industry. 1942, World War II: The automotive plants stopped building cars so they could focus on building tanks and military vehicles for the war. These tanks were equipped with the Hydra-Matic Transmission. During the post-war time, the demand for vehicles with the Hydra-Matic was high. By this point, ¾ of General Motors cars sold came equipped with this option.
***Note: Over 200,000 Hydra-Matics were sold during the war.
M-5 Stuart tank with Hydra-Matic Transmission
The Torque Converter
The first hydraulic transmission to have a torque converter was the Dynaflow, introduced by Buick in 1948. The Dynaflow only had two forward gears and reverse. With the torque converter multiplying torque and power it made the 2-speed very powerful and efficient for its time. Packard designed the 2-speed Ultramatic fully automatic transmission in 1949. The King of the hill was General motor Power Glide in 1950. The Power Glide is still used today in top fuel and many ¼ mile racing cars as the king of automatic transmissions for race application (with some mods).
General Motors Power Glide AT
Borg Warner introduced the first automatic transmission with 3 speeds and the use of a lock-up torque converter. By the mid-1950's, almost all major car companies including Bentley, Lincoln, Ford and Studebaker purchased 3-speed automatic hydraulic transmissions from General Motors.
***Note: The use of Whale Sperm Oil for lubricating the AT was discontinued around 1960.
The Overdrive Transmission was introduced in the late 1970’s (4-speed AT with a lock converter). It was more fuel efficient than previous models due to higher gear ratios at highway speed.
General Motors 4L60 E Overdrive Transmission
Today we have transmissions with up to 11-speed gear trains which incorporate the use of electronic control solenoids, variable speed sensors, and are computer controlled. The CVT Transmission is a hydraulic chain driven AT. We now also have front wheel drive, all-wheel drive, transaxles, transfer cases and 4x4 transmissions.
Auto Service Experts employs ASE certified master mechanics with over 20 years experience specializing in repairing, rebuilding, maintaining, and servicing automatic transmissions, manuals, CVTs, and diesels.