Frank’s Patent Model of an Opposed Piston Steam Engine - 1875
date: label: date made
content: ca 1870
label: patent date
content: 1875-10-26
name: label: inventor
content: Frank, Samuel B.
notes: label: Description
content: This model was filed with the application to the U.S. Patent Office for Patent Number 169,249 issued to Samuel B. Frank of Marshall, Missouri on October 26, 1875. The patent was for an opposed piston steam engine with four pistons. The goal of the design was to reduce vibration caused by unbalanced reciprocating masses.
label: Description
content: The four pistons were equally spaced within a single cylinder, and each cylinder traversed one fourth of the length of the cylinder. The two inner pistons were arranged to move towards each other while the outer pistons would move away from each other. The reverse order would take place on the next cycle. A single slide valve with multiple ports fed steam to the appropriate volumes between the pistons. Each piston had its own crosshead, two on the left of the engine and two on the right. Concentric piston rods were used to allow the rods for the outer pistons to pass inside those for the inner pistons.
label: Description
content: The use of the two pairs of opposed pistons was claimed to reduce vibration, and Frank also claimed the engine would be more powerful than standard engines. As shown in the image the design was complex and had many moving parts and wearing surfaces. It is not known how practical the design was to manufacture and operate. A search of available literature did not produce any examples of actual use of the patent.
label: Description
content: The patent model is made of brass and mounted on a wood base. It is highly detailed and illustrates all of the key details of the patent. A full description of the operation of the engine along with complete diagrams of the patent can be found in the patent document online at the United States Patent and Trademark Office website, www.uspto.gov.
place: label: associated place
content: United States: Missouri, Marshall
topic: label: Subject
content: Patent Models
label: Subject
content: Steam Engines
setName: label: See more items in
content: Work and Industry: Mechanical and Civil Engineering
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content: Engineering, Building, and Architecture
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content: Patent Models
label: Exhibition
content: Power Machinery
label: Exhibition Location
content: National Museum of American History
creditLine: label: Credit Line
content: Gift of D. C. Public Schools, Department of Science, Washington, D. C.
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MC.321889
label: accession number
content: 245986
label: patent number
content: 169,249
label: catalog number
content: 321889
objectType: label: Object Name
content: engine, steam, double opposed piston, Frank, 1875
label: Object Name
content: patent model, engine, steam
physicalDescription: label: Measurements
content: overall: 6 in x 8 in x 14 in; 15.24 cm x 20.32 cm x 35.56 cm