Former Portlander to Receive Award

The Oregon Journal  Jan. 1964

By Rolla J. Crick

Journal Automotive Editor


Earl A. Thompson, who as a youth in Portland invented the synchromesh transmission and later led development of the Hydra-Matic transmission will be honored in Detroit Wednesday by receipt of the Elmer A. Sperry Award.


Presentation of the award will be made at the Society of Automotive Engineers congress at Cobb Hall.  The citation hails Thompson’s “outstanding leadership and genius exhibited in the design and development of the first notably successful automobile transmission capable of automatically changing drive ratio without perceptible relaxation of drive torque.”


Five members of the team that worked with Thompson to turn his concept into a production item will receive special citations.  They are Ralph F. Beck, William L. Carnegie, Walter B. Herndon, Oliver F. Kelley and Maurice S. Rosenberger.


THOMPSON, born in Elgin and raised in Gresham and Portland, was a familiar figure in Portland streets in the 1920s, driving Cadillac, Rickenbacker and Buick automobiles in which he was testing his transmission.  His models were made by Coin Manufacturing Co. and included a selective feature mounted on the steering column.


In 1925 he went to Detroit to show what he had invented.  Cadillac  liked his idea for the synchromesh transmission which “for the first time enabled a driver to shift from low to second and from second to high or vice versa while the car is operating at any speed and without clashing of gears.”


Publicity releases explained that this silent shifting was accomplished by means of a separate cone clutch which synchronized speed of the engine with speed of the gears.


THE DEVICE reached production for the 1928 Cadillac.  In 1929 Thompson became assistant chief engineer for Cadillac and later began trying to improve what he had invented.


In 1930 he sold his patents outright to General Motors.  One report was that he obtained $1 million.


When he was asked about it in Portland,  Thompson said, “you know there are a lot of strange rumors going around.  You know the popular kind of biographical story is to tell how a man sold peanuts on First and Burnside St. when a boy to keep his starving parents out of the poor house, and then the lad grew up to be a multimillionaire and president of the railroad company.  I don’t go in for that sort of stuff.”


He never revealed how much he received.


In 1932 Cadillac gave him a free hand in selecting a project team to work on a step-ratio transmission in which shifting would be accomplished by hydraulic servomechanisms.  The team called the device a “military transmission” and by 1936 had evolved a semi-automatic four-speed planetary transmission.  It required the conventional clutch for starting and one manual shift from a two-speed automatic low range to a two-speed automatic high range.  The shift was made under power without use of a clutch pedal.


GENERAL redesign of the production for semi-automatic was started in 1936.  Incorporation of a planetary reverse gear replacing the sliding gear arrangement and evolution of a four-stage split-torque fluid coupling which eliminated the clutch pedal, combined with a hydraulic governor and pressure modulator system for automatic control.  These were the necessary elements for a fully automatic passenger car transmission.


It was given the name Hydra-Matic and came out in the 1940 Oldsmobiles.  Since then, 13 million Hydra-Matic have been produced.


Thompson left GM in 1939 to begin his own business, the E.A. Thompson Manufacturing Co. In Ferndale, Mich.  He continued for a time, however to serve as a consultant to GM.


Thompson’s firm engineers and produces hydraulic valve lifters.  Thompson has a daughter, Mrs. Vincent S. Smith, and six grandchildren living at 2635 NE 40th Ave. in Portland.






Updated: October 20, 2017