e/Expansion valve

Information
has gloss	eng: An expansion valve is a slide valve used in a steam engine to control the cut-off. It rides on the back of an adapted main slide valve and is driven by an additional eccentric that has more advance than the main eccentric. The cut-off is adjusted in one of two ways. The stroke of the expansion valve may be altered by adjusting the throw of the eccentric or by an expansion link and radius rod arrangement, usually under the control of a centrifugal governor. Alternatively, the effective length of the expansion valve can be altered. The Meyer expansion valve has two heads mounted on opposite-handed threads on a rotatable valve rod, so that rotating the rod moves the heads either together or apart, according to the direction of rotation. In this arrangement the cut-off is normally controlled manually. The engines at Coleham Pumping Station have Meyer expansion valves on the high-pressure cylinders.
lexicalization	eng: expansion valve
instance of	(noun) external-combustion engine in which heat is used to raise steam which either turns a turbine or forces a piston to move up and down in a cylinder steam engine