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:
“I always consider the settlement of America with reverence and wonder, as the opening of a grand scene and design in providence, for the illumination of the ignorant and the emancipation of the slavish part of mankind all over the earth.”
—John Adams (1735–1826)
“[The sceptic] must acknowledge, if he will acknowledge any thing, that all human life must perish, were his principles to prevail. All discourse, all action would immediately cease, and men remain in a total lethargy, till the necessities of nature, unsatisfied, put an end to their miserable existence.”
—David Hume (1711–1776)