Expansion valve
Encyclopedia
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.
Steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...
to control the cut-off
Cut-off
A cut-off, also known as a kutte or "battle jacket" in heavy metal subcultures, is a type of vest or jacket which originated in the biker subculture and has now found popularity in the punk and various heavy metal subcultures...
. It rides on the back of an adapted main slide valve and is driven by an additional eccentric
Eccentric (mechanism)
In mechanical engineering, an eccentric is a circular disk solidly fixed to a rotating axle with its centre offset from that of the axle ....
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
Centrifugal governor
A centrifugal governor is a specific type of governor that controls the speed of an engine by regulating the amount of fuel admitted, so as to maintain a near constant speed whatever the load or fuel supply conditions...
. 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
Coleham Pumping Station
Coleham Pumping Station is a historical pumping station in Coleham, Shrewsbury, England.-History:The sewage pumping station was built at the end of the 19th century as part of a major upgrading of Shrewsbury's sewerage system...
have Meyer expansion valves on the high-pressure cylinders.