Demonstration Model of a Slide Valve for a Steam Engine

Demonstration Model of a Slide Valve for a Steam Engine

Usage conditions apply
Downloads
Description
This is a demonstration model of a slide valve for a steam engine. By about 1820 such valves had evolved as the simplest devices for controlling the steam inlet and exhaust for a steam engine cylinder. This type of valve was operated by an eccentric that caused it to slide back and forth, alternately opening ports for inlet and exhaust at each end of the cylinder. Inlet steam was cut off when the inlet port closed at a fixed point in the stroke of the engine.
The speed of the engine was controlled by throttling the steam supply. No provision was made for adjusting the point of cut off while the engine was running. This feature was added in later evolutions of valve designs resulting in increased efficiency and the ability for automatic control of the speed of the engine. Several patent and demonstration models of such variable cut off valves are included in the collections.
The model was built to operate and show how the valve functioned. It shows a steam cylinder and valve case in cross section. The crankshaft of the engine is at the right of the model, and the eccentric is seen mounted on that shaft. The eccentric operates a crank arm which in turn operates the D valve. A steam pressure versus volume curve is shown below the cylinder. A label at the right of the model describes the functioning of the valve. A separate label on the top of the model case describes the limitations of the valve design.
Object Name
Engine, Steam, Valve Gear
engine, steam, slide valve, model
maker
Severn-Lamb Ltd.
Measurements
overall: 12 in x 18 in; 30.48 cm x 45.72 cm
ID Number
MC.325394
catalog number
325394
accession number
253584
subject
Steam Engines
Model
See more items in
Work and Industry: Mechanical and Civil Engineering
Engineering, Building, and Architecture
Exhibition
Power Machinery
Exhibition Location
National Museum of American History
Data Source
National Museum of American History
Nominate this object for photography.   

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.

Comments

Add a comment about this object