Corliss Vacuum Dash Pot, Patent Model

The model was filed on October 27, 1875, to the U.S. Patent Office with the application for the patent issued to George H. Corliss, June 6, 1876, no. 178275.
The model is a brass miniature of a vacuum dash pot designed to combine the functions of supplying the force to close the steam valve and to arrest the motion without shock after the valve is closed. The vacuum dash pot has some advantages over heavy weights and springs for closing valves.
The dash pot consists of a casting in which is bored a cylinder having a lower section of small diameter and an upper section of larger diameter. A plunger, having corresponding sections of large and small diameters, fits the cylinder. When the steam valve to which the plunger is attached is opened the plunger rises in the cylinder forming a vacuum in the part of smaller diameter. At the same time small leather valves in the larger part of the plunger open and allow air to enter the cylinder under this part of the plunger. When the valve is released the vacuum draws down the plunger and closed the valve. The air under the upper part escapes through a port in the cylinder until the plunger covers the port. The air trapped in the cylinder at this point acts a s a cushion and brings the valve quickly but gently to rest.
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
Corliss, George H.
place made
United States: Rhode Island
associated place
United States: Rhode Island, Providence
Physical Description
brass (overall material)
overall: 6 1/2 in x 2 3/4 in; 16.51 cm x 6.985 cm
brass cylinder - from catalog card: 6 in; 15.24 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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