![]() ![]() Hydra-Matic Drive, as it was originally named, was developed by a team led by Earl Thompson (the creator of Synchromesh) that began as a Cadillac program in 1932 and was then moved to GM Central Research in 1936. Naturally, a variety of gearsets were used through the years to suit a wide range of specific applications. On the original Olds Hydra-Matic, the four ratios, first through fourth gears, were 3.66:1, 2.53:1, 1.44:1, and 1.00:1. One key difference: While contemporary transmissions use a torque converter coupling to supply mechanical advantage for low-speed acceleration, the Hydra-Matic employs a straight fluid coupling with an effective ratio of 1:1-hence the need for four forward speeds. ![]() There were three planetary gearsets to provide four forward speeds and reverse, with the gearchanges accomplished via clutches, bands, and hydraulic pressure. In its internal operation as well, the Hydra-Matic was much like the automatics of the current day. The column indicator was marked “N-Hi-Lo-R” or similar. One difference worth mentioning: On the original Hydra-Matics, there was no Park position as such on the gear selector. It was fully and truly automatic in operation, just like the automatic transmissions of today: Just place the selector in “Drive” and off you go. Preselector transmissions, including Hudson and Cord in the USA, Wilson in the UK, and Cotal in France, came closer still.īut in the Hydra-Matic, there was no gear shifting required once the car was under way, and there was no clutch pedal. The Model T Ford, with its two-speed planetary transmission, was hard to beat for ease of operation, though it wasn’t a real automatic as we know it. When we describe the 1940 Oldsmobile Hydra-Matic as the first truly automatic transmission in volume production-the first modern automatic, if you will-we also recognize all the worthy attempts that came before it. We want to choose our terms with care here. When Hydra-Matic was introduced by Oldsmobile in 1940, General Motors called it “the most important automotive advancement since the self-starter.” Here’s a closer look. ![]()
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