Davies Steam Pump, Patent Model

This model was submitted to the U.S. Patent Office with the application for the patent issued to Joseph D. Davies, of Covington, Kentucky, March 9, 1880, no. 225351.
The model represents a direct-acting steam pump, provided with two auxiliary oscillating cylinders, which offer a constantly decreasing resistance to the movement of the steam piston during the first half of its stroke and a constantly increasing assistance during the remaining half. The purpose of this is to equalize the effective force of the steam piston throughout its stroke when the steam is used expansively.
The two auxiliary cylinders are mounted in trunnions, one on each side of the frame of the engine. The rods from the auxiliary pistons are attached to a clamp on the main piston rod, so located that the auxiliary cylinders are perpendicular to the main piston rod when the main piston is at midstroke. The auxiliary pistons, in the model, work against a spiral spring, which is compressed during the first half of the stroke and which expands during the last half. In effect the springs act as would a flywheel, storing the energy in excess of the resistance, while steam at high pressure acts upon the engine piston, and delivering the stored energy after the steam has been cut off and is expanding in the cylinder. The inventor described his device using a fluid, as steam or water under pressure within the auxiliary cylinders.
This description comes from the 1939 Catalog of the Mechanical Collections of the Division of Engineering United States Museum Bulletin 173 by Frank A. Taylor.
Currently not on view
Object Name
pump, steam, model
patent model, engine, steam
date made
patent date
Davies, Joseph D.
Physical Description
brass (overall material)
overall: 2 3/4 in x 5 5/8 in x 10 5/8 in; 6.985 cm x 14.2875 cm x 26.9875 cm
place made
United States: Kentucky
associated place
United States: Kentucky, Covington
ID Number
catalog number
accession number
patent number
Engineering, Building, and Architecture
Industry & Manufacturing
Bulletin 173
Patent Models
Patent Models
Steam Engines
See more items in
Work and Industry: Mechanical and Civil Engineering
Bulletin 173
Patent Models
Data Source
National Museum of American History, Kenneth E. Behring Center
Related Publication
Frank A. Taylor. Catalog of the Mechanical Collections of the Division of Engineering United States National Museum, Bulletin 173

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