Kelly and Lamb’s Patent Model of a Steam Engine Governor – ca 1865

Kelly and Lamb’s Patent Model of a Steam Engine Governor – ca 1865

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Usage conditions apply
This model was filed with the application to the U.S. Patent Office for Patent Number 46,111 issued to Oliver A. Kelly and Estus Lamb of Slatersville, Rhode Island on January 31, 1865. The patent was for an improvement in controlling the speed of a steam engine by use of a fly ball governor.
Kelly and Lamb claimed their design reduced violent fluctuations in the amount of steam admitted to the cylinder due to sudden, large increases or decreases in the load on the engine. The design was based on a standard fly-ball governor which was used to sense if the engine's speed deviated from its desired speed. However, instead of using the motion of the fly-balls themselves to adjust the steam valve, they used an escapement that rotated a screw-thread which was linked to the steam valve. The escapement was rotated by a rocker arm attached to a crank operated from the main shaft of the governor. When the escapement was activated, each rotation of the governor shaft would cause a small increase or decrease in the travel of the screw-thread and thus a small adjustment to the steam valve. The escapement would continue to adjust the engine's speed until the fly-balls once again attained their preset speed at which time the escapement would be neutralized. A search of available literature did not reveal any practical use of the Kelly Lamb governor.
The patent model is constructed of cast iron and steel. All of the key elements of the patent are illustrated by the model to include the escarpment mechanism. Diagrams showing the complete design of the patent can be found in the patent document online at the United States Patent and Trademark Office website,
Object Name
governor, steam, indirect, model
patent model, governor, steam engine
date made
patent date
Kelly, Oliver A.
Lamb, Estus
place made
United States: Rhode Island
associated place
United States: Rhode Island, Slatersville
governor: 12 in x 6 in x 6 in; 30.48 cm x 15.24 cm x 15.24 cm
ID Number
catalog number
accession number
patent number
Patent Models
Steam Engines
See more items in
Work and Industry: Mechanical and Civil Engineering
Patent Models
Engineering, Building, and Architecture
Power Machinery
Exhibition Location
National Museum of American History
Data Source
National Museum of American History
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