Revolutionizing the Road: Unveiling the World’s First Automatic Transmission Vehicle
The 1904 Sturtevant “horseless carriage gearbox” stands as a pivotal development in automotive history, often credited as the earliest automatic transmission for motor vehicles. Originating in Boston, USA, this transmission featured two forward gear ratios and engine-driven flyweights that dictated gear selection. The mechanism engaged high gear at higher engine speeds and reverted to low as the vehicle decelerated, aligning with engine RPM fluctuations. However, the transmission faced issues of abrupt gear changes leading to sudden failures.
A significant stride towards contemporary automatic transmissions was the adoption of planetary gearsets. The 1901-1904 Wilson-Pilcher automobile’s manual transmission in the United Kingdom was among the first to implement this design, utilizing two epicyclic gears for four gear ratios. While a foot clutch facilitated standing starts, gear selection employed a hand lever, helical gears minimized noise, and a constant-mesh design enhanced functionality. The 1908 Ford Model T also incorporated a planetary gearset in its two-speed manual transmission, albeit without helical gears.
The pursuit of automatic transmission saw an early patent in 1923 by Canadian inventor Alfred Horner Munro, utilizing compressed air but lacking commercial viability. A subsequent 1923 U.S. patent by Henry R. Hoffman introduced the concept of eliminating manual gear shifting and clutch operation, paving the way for future innovations. However, mass-produced automatic transmissions were still over a decade away.
The first automatic transmission employing hydraulic fluid emerged in 1932, courtesy of Brazilian engineers José Braz Araripe and Fernando Lehly Lemos. The evolution continued with the 1933-1935 REO Motor Car Company Self-Shifter semi-automatic transmission, which automatically shifted between forward gears in the “Forward” mode. The driver’s involvement remained essential for standing starts. In 1937, the Oldsmobile Automatic Safety Transmission followed a similar principle, using a planetary gearset for automatic shifts between two gear ratios in the “Low” and “High” ranges. The Chrysler Fluid Drive, introduced in 1939, offered an optional fluid coupling for manual transmissions, eliminating the need for a manual clutch. This marked another milestone on the journey towards widespread adoption of automatic transmissions in the automotive landscape.