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In a steam engine, cutoff is the point in the piston stroke at which the inlet valve is closed. On a steam locomotive, the cutoff is controlled by the reversing gear.. The point at which the inlet valve closes and stops the entry of steam into the cylinder from the boiler plays a crucial role in the control of a steam engine.
With larger engines, the linkages involved in controlling cutoff and direction grew progressively heavier and there was a need for power assistance in adjusting them. Steam (later, compressed air) powered reversing gears were developed in the late 19th and early 20th centuries.
The first kind is the steam lap, which is the amount by which the valve overlaps the steam port on the live steam side of the piston or slide valve (i.e. the distance the valve needs to move to just begin to uncover the port).
Collects steam at the top of the boiler (well above the water level) so that it can be fed to the engine via the main steam pipe, or dry pipe, and the regulator/throttle valve. [2] [5] [6]: 211–212 [3]: 26 Air pump / Air compressor Westinghouse pump (US+) Powered by steam, it compresses air for operating the train air brake system.
Cross compound engine, with an expansion valve (top) on the high-pressure cylinder. An expansion valve is a device in steam engine valve gear that improves engine efficiency. It operates by closing off the supply of steam early, before the piston has travelled through its full stroke. This cut-off allows the steam to then expand within the ...
where d is the bore of the cylinder (diameter) in inches, s is the cylinder stroke, in inches, P is boiler pressure in pounds per square inch, D is the diameter of the driving wheel in inches, and c is a factor that depends on the effective cut-off. [83] In the US, c is usually set at 0.85, but lower on engines that have maximum cutoff limited ...
A compound steam engine unit is a type of steam engine where steam is expanded in two or more stages. [ 1 ] [ 2 ] A typical arrangement for a compound engine is that the steam is first expanded in a high-pressure (HP) cylinder , then having given up heat and losing pressure, it exhausts directly into one or more larger-volume low-pressure (LP ...
Frederick Ellsworth Sickels (September 20, 1819; [1] Gloucester County, New Jersey – March 8, 1895; Kansas City [2]) was an American inventor, best known for the invention of a cut-off valve for steam engines in 1841. Sickels grew up in New York City, [3] where his father was Chief Health Officer. [4]