Allen’s Patent Model of Cut-Off Valve for Steam Engines – ca 1841


This model was filed with the application to the U.S. Patent Office for Patent Number 2,227 issued to Horatio Allen of New York, New York on August 21, 1841. The patent was for an improved design for the mechanism controlling the inlet valve of a steam engine. Allen’s design provided a means of adjusting the point in the power stroke of the engine’s piston at which high pressure steam being fed to the cylinder was cut off. This was desirable as power was extracted from the expansive force of the steam after the valve closed. This saved fuel by avoiding continuous use of high pressure steam.

The image of the model shows a cross section of the steam cylinder at the right with the piston rod and connecting rod extending to the left to the crankshaft. The steam inlet valve is shown above the cylinder and is of the slide valve type. It is operated by a shaft eccentric mounted on the crankshaft. In the model, the valve is made of wood and slides back and forth to admit steam to each side of the piston. The cut-off is the separate brass slide valve above the main valve. It is operated by its own eccentric, and the range of its travel is controlled by the brass hand crank and gears. Turning the crank thus allowed the point of steam cut-off to be varied as required.

Allen’s design in this patent was soon improved by himself and others to allow for a simpler mechanism that did not require the separate slide valve for cut-off.

The patent model is constructed of brass and wood. All of the key elements of the patent are illustrated by the model. It includes a small hand crank to permit demonstration of actual operation. A full description of the operation of the valve gear along with complete diagrams of the patent can be found in the patent document online at the United States Patent and Trademark Office website,

Date Made: 1841Patent Date: 1841-08-21

Inventor: Allen, Horatio

Place Made: United States: New YorkAssociated Place: United States: New York, New York City

Subject: Patent ModelsSteam Engines


See more items in: Work and Industry: Mechanical and Civil Engineering, Engineering, Building, and Architecture, Patent Models

Exhibition: Power Machinery

Exhibition Location: National Museum of American History

Related Publication: Frank A. Taylor. Catalog of the Mechanical Collections of the Division of Engineering United States National Museum, Bulletin 173

Data Source: National Museum of American History

Id Number: MC.308649Catalog Number: 308649Accession Number: 89797Patent Number: 2,227

Object Name: engine, steam, cut off valveengine, steam, cut off valve, modelpatent model, valve, steam engine cut off

Measurements: on block: 8 in x 32 in; 20.32 cm x 81.28 cm


Record Id: nmah_846133

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