Turbo-Hydramatic is the registered tradename of a family of automatic transmission

Automatic transmission

An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...

s developed and produced by General Motors. These transmissions mate a three-element torque converter

Torque converter

In modern usage, a torque converter is generally a type of hydrodynamic fluid coupling that is used to transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating driven load...

 to a Simpson

Howard Simpson

Howard Woodworth Simpson was an automotive engineer whose designs were extensively used in automatic transmissions.-Biography:...

 planetary geartrain

Epicyclic gearing

Epicyclic gearing or planetary gearing is a gear system consisting of one or more outer gears, or planet gears, revolving about a central, or sun gear. Typically, the planet gears are mounted on a movable arm or carrier which itself may rotate relative to the sun gear...

, providing three forward speeds

Gear ratio

The gear ratio of a gear train is the ratio of the angular velocity of the input gear to the angular velocity of the output gear, also known as the speed ratio of the gear train. The gear ratio can be computed directly from the numbers of teeth of the various gears that engage to form the gear...

 plus reverse.

The Turbo-Hydramatic (THM) series was developed to replace both the original Hydra-Matic models

Hydramatic

Hydramatic was an automatic transmission developed by both General Motors' Cadillac and Oldsmobile divisions. Introduced in 1939 for the 1940 model year vehicles, the Hydramatic was the first fully automatic mass-produced transmission developed for passenger automobile use.-History:During the...

 and the Buick

Buick

Buick is a premium brand of General Motors . Buick models are sold in the United States, Canada, Mexico, China, Taiwan, and Israel, with China being its largest market. Buick holds the distinction as the oldest active American make...

 Dynaflow

Dynaflow

Dynaflow was the trademark name for a type of automatic transmission developed and built by General Motors' Buick Motor Division from the late 1940s to the mid 1963...

. In its original incarnation as the Turbo-Hydramatic 400, it was first used in the 1964 model year in Cadillac

Cadillac

Cadillac is an American luxury vehicle marque owned by General Motors . Cadillac vehicles are sold in over 50 countries and territories, but mostly in North America. Cadillac is currently the second oldest American automobile manufacturer behind fellow GM marque Buick and is among the oldest...

s.