Design Principles
When on the move, a steam locomotive requires steam to enter the piston at a controlled rate. This entails controlling the admission and exhaustion of steam to and from the cylinders. Steam enters and leaves the valve through a steam port, usually at the middle position of the piston valve. Where the valve is in contact with the steam ports, a consideration of the "lap" and "lead" is required.
Read more about this topic: Piston Valve (steam Engine)
Famous quotes containing the words design and/or principles:
“What but design of darkness to appall?—
If design govern in a thing so small.”
—Robert Frost (1874–1963)
“Government ... thought [it] could transform the country through massive national programs, but often the programs did not work. Too often they only made things worse. In our rush to accomplish great deeds quickly, we trampled on sound principles of restraint and endangered the rights of individuals.”
—Gerald R. Ford (b. 1913)