Construction
The valve is usually either a flat disc or a poppet valve which may be either opened or closed by gravity. In one configuration the valve is lifted onto its seat by steam pressure and falls away under gravity when steam is shut off. This allows air to be drawn freely through it. Alternatively, the valve rests on its seat under gravity and is lifted by inward air flow, which can give rise to a characteristic rattle when a locomotive is coasting.
Read more about this topic: Snifting Valve
Famous quotes containing the word construction:
“No real “vital” character in fiction is altogether a conscious construction of the author. On the contrary, it may be a sort of parasitic growth upon the author’s personality, developing by internal necessity as much as by external addition.”
—T.S. (Thomas Stearns)
“There’s no art
To find the mind’s construction in the face:
He was a gentleman on whom I built
An absolute trust.”
—William Shakespeare (1564–1616)
“There’s no art
To find the mind’s construction in the face.”
—William Shakespeare (1564–1616)