Loper Marine Steam Engine, Patent Model

This model was submitted to the U.S. Patent Office with the application for the patent issued to R. F. Loper, of Philadelphia, Pennsylvania, August 28, 2849, no. 6673.
This is a nicely made working model of a 2-cylinder vertical marine engine directly connected to a 2-throw propeller shaft, upon which is mounted a 4-blade propeller. The model is complete with boiler, feed-water pump, condenser, and condenser air pump. The peculiar feature of the invention is the manner of connecting the air pump to the engine and the method of quickly converting the engine from condensing to noncondensing operation.
The engine represented consists of a heavy bed plate shaped to fit the hull of a vessel, upon which are attached the bearing of the propeller shaft and the frame that supports the cylinders. The cylinders are double-acting are “reversed from the ordinary position of engines, the piston rod running down through the lower head and connecting by the usual connecting rod with the cranks on the shaft below.” “The valves of the engine take their motion from eccentrics on the main shaft coupled with a valve lever by proper eccentric rods. The lever is affixed to its axis by its center and is made double, so that the eccentric rod can be thrown to either end to reverse the motion or may be wholly detached.” The cur-off is worked directly from the cross head. The air pump is driven by a beam and connecting rod, which is driven by a crankpin upon a gear wheel that engages a pinion on the crankshaft. The ratio of the gears is such that the air pump performs only one stroke to two of the engine. The air pump communicates with the condenser into which the exhaust pipe opens. The escape pipe is also connected with the condenser, which, when open, allows the steam to escape without condensing.
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
date made
patent date
Loper, R. F.
place made
United States: Pennsylvania
associated place
United States: Pennsylvania, Philadelphia
overall: 7 7/8 in x 4 1/2 in x 18 1/4 in; 20.0025 cm x 11.43 cm x 46.355 cm
overall - from catalog card: 4 in x 18 in; 10.16 cm x 45.72 cm
ID Number
accession number
catalog number
patent number
See more items in
Work and Industry: Mechanical and Civil Engineering
Industry & Manufacturing
Bulletin 173
Engineering, Building, and Architecture
Data Source
National Museum of American History


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