Corliss steam engine#Corliss valves
{{Short description|Type of steam engine using rotary steam valves}}
File:Corliss engine, showing valvegear (New Catechism of the Steam Engine, 1904).jpg
A Corliss steam engine (or Corliss engine) is a steam engine, fitted with rotary valves and with variable valve timing patented in 1849, invented by and named after the US engineer George Henry Corliss of Providence, Rhode Island. Corliss assumed the original invention from Frederick Ellsworth Sickels (1819- 1895), who held the patent (1829) in the US patent office.
Engines fitted with Corliss valve gear offered the best thermal efficiency of any type of stationary steam engine until the refinement of the uniflow steam engine and steam turbine in the 20th century. Corliss engines were generally about 30 percent more fuel efficient than conventional steam engines with fixed cutoff.{{cite journal |author1=Rosenberg |author2=Trajtenberg |title=A General Purpose Technology at Work |journal=The Journal of Economic History |volume=64 |issue=1 |date=March 2004 |page=75}} This increased efficiency made steam power more economical than water power, allowing industrial development away from millponds.{{cite book |author=Diana Muir |author-link=Diana Muir |title=Reflections in Bullough's Pond |publisher=University Press of New England |date=2000 |page=[https://archive.org/details/reflectionsinbul00dian/page/173 173]|title-link=Reflections in Bullough's Pond }}
Corliss engines were typically used as stationary engines to provide mechanical power to line shafting in factories and mills and to drive dynamos to generate electricity. Many were quite large, standing many metres tall and developing several hundred horsepower, albeit at low speed, turning massive flywheels weighing several tons at about 100 revolutions per minute. Some of these engines have unusual roles as mechanical legacy systems and because of their relatively high efficiency and low maintenance requirements, some remain in service into the early 21st century. See, for example, the engines at the Hook Norton Brewery and the Distillerie Dillon in the list of operational engines.
Corliss engine mechanisms
Corliss engines have four valves for each cylinder, with steam and exhaust valves located at each end. Corliss engines incorporate distinct refinements in both the valves themselves and in the valve gear, that is, the system of linkages that operate the valves.
The use of separate valves for steam admission and exhaust means that neither the valves nor the steam passages between cylinders and valves need to change temperature during the power and exhaust cycle, and it means that the timing of the admission and exhaust valves can be independently controlled. In contrast, conventional steam engines have a slide valve or piston valve that alternately feeds and exhausts through passages to each end of the cylinder. These passages are exposed to wide temperature swings during engine operation, and there are high temperature gradients within the valve mechanism.
Clark (1891) commented that the Corliss gear "is essentially a combination of elements previously known and used separately, affecting the cylinder and the valve-gear".{{cite book |last=Clark |first=Daniel K. |author-link=Daniel Kinnear Clark |title=The Steam Engine |year=1891 |publisher=Blackie & Son |location=London |volume=Half-vol.3 |page=39}} The origins of the Corliss gear with regard to previous steam valve gear was traced by Inglis (1868).{{cite journal|last=Inglis|first=William|title=On the Corliss expansion valve-gear for stationary engines|journal=Proceedings of the Institution of Mechanical Engineers|volume=19|year=1868|pages=177–194 and plates 88 to 97 |url=https://archive.org/details/proceedingsinst01britgoog|doi=10.1243/PIME_PROC_1868_019_017_02}}
=Corliss valve gear=
File:Corliss valvegear, Gordon's improved (New Catechism of the Steam Engine, 1904).jpg
George Corliss received {{US patent|6162}} for his valve gear on March 10, 1849. This patent covered the use of a wrist-plate to convey the valve motion from a single eccentric to the four valves of the engine, and it covered the use of trip valves with variable cutoff under governor control that characterize Corliss Engines.{{cite patent|country=US|number=6162A|pubdate=1849-03-10|title=Cut-off and working the valves of steam engines|inventor1-last=Corliss|inventor1-first=George H.}} Unlike later engines, most of which were horizontal, this patent describes a vertical cylinder beam engine, and it used individual slide valves for admission and exhaust at each end of the cylinder.
The inlet valves are pulled open with an eccentric-driven pawl; when the pawl trips, the rapid closure is damped using a dashpot. In many engines, the same dashpot acts as a vacuum spring to pull the valves closed, but Corliss's early engines were slow enough that it was the weight of the dashpot piston and rod that closed the valve.
The speed of a Corliss engine is controlled by varying the cutoff of steam during each power stroke, while leaving the throttle wide open at all times. To accomplish this, the centrifugal governor is linked to a pair of cams, one for each admission valve. These cams determine the point during the piston stroke that the pawl will release, allowing that valve to close.
As with all steam engines where the cutoff can be regulated, the virtue of doing so lies in the fact that most of the power stroke is powered by the expansion of steam in the cylinder after the admission valve has closed. This comes far closer to the ideal Carnot cycle than is possible with an engine where the admission valve is open for the length of the power stroke and speed is regulated by a throttle valve.
The Corliss valve gearing allowed more uniform speed and better response to load changes, making it suitable for applications like rolling mills and spinning, and greatly expanding its use in manufacturing.{{cite book|title=A History of Control Engineering 1800-1930 |last=Benett |first= Stuart|year=1986 |publisher =Institution of Engineering and Technology
=Corliss valves=
File:Corliss cylinder section 2.png
File:Corliss Cylinder.jpg and cylinder cross section showing the path of high-pressure steam (in red) and low-pressure steam (in blue). With each stroke, the four valves alternate opening and closing, driving the piston back and forth]]
Corliss valves open directly into the cylinder. The valves connect the cylinder to separate steam and exhaust plenums. Initially, Corliss used slide valves with linear actuators, but by 1851, Corliss had shifted to semi-rotary valve actuators, as documented in U.S. Patent 8253.{{cite patent|country=US|number=8253A|pubdate=1851-07-29|title=Cut-off gear|inventor1-last=Corliss|inventor1-first=George H.}} In this engine, the wrist plate was moved to the center of the cylinder side, as on later Corliss engines. This was still a beam engine, however, and the semi-rotary valve actuators operated linear slide valves inside the four valve chests of the engine.
Corliss valves are in the form of a minor circular segment, rotating inside a cylindrical valve-face. Their actuating mechanism is off along the axis of the valve, thus they have little "dead space" such as the stem of a poppet valve and the entire port area can be used efficiently for gas flow.
As the area of a Corliss valve is small compared to the port area, the effects of gas flow generate relatively little torque on the valve axle compared to some other sorts of valve. These advantages have led to the Corliss form of valve being used in other roles, apart from steam engines with Corliss gear.
The Rolls-Royce Merlin aero-engine used a rectangular butterfly valve as a throttle. Gas-flow forces acting asymmetrically on this butterfly could lead to poor control of the power in some circumstances. Late models, from the 134, used a Corliss throttle valve instead to avoid this problem.{{cite book
|title=The Merlin 100 series
|publisher=Rolls-Royce Heritage Trust
|author1=Harvey-Bailey, Alec |author2=Piggott, Dave
|isbn=1-872922-04-X
|year=1993
}}
=Barring and barring engines=
A common feature of large Corliss engines is one or two sets of narrow gear teeth in the rim of the flywheel.{{cite book|url=https://books.google.com/books?id=DRhMAAAAMAAJ&q=barring%20flywheel%20steam%20engine&pg=PA234 |title=Barring diagrams |author=Norman, W. |publisher=Henley Publishing |date=1919 |access-date=6 December 2011}} These teeth allow the flywheel to be barred, that is, turned with the aid of a crowbar.The crowbar for barring the engines is visible in [http://www.internationalsteam.co.uk/mills/pics04/in04036.jpg this photo] from the [http://www.internationalsteam.co.uk/mills/indiamill01.htm Saraya Sugar Factory] This may be needed during engine maintenance, for example, to set the cutoff and admission valve timing, and it may be needed during engine starting.
The need for barring the engine during starting is most obvious on single-cylinder engines, where a careless engine operator might stop the engine with the piston in or near dead center. Once stopped in this state, the engine cannot be started under its own power, so it must be barred to a more favorable position for starting.
Large Corliss engines cannot be safely started cold,{{why|date=November 2016}} so it is common to admit low-pressure steam to both sides of the cylinder to warm up the metalwork. Turning the engine slowly during this process ensures that the entire engine is uniformly warmed, and it ensures that oil is uniformly distributed through the mechanism before applying power.{{cite web |website=Straffan Steam Museum |url=http://www.steam-museum.com/Aboutus.html |title=About Us |archive-url=https://web.archive.org/web/20080907144753/http://www.steam-museum.com/Aboutus.html |archive-date=2008-09-07 }} See section "More about the stationary engines", subsection Single Cylinder MILL Engine, Instructions To Start Engine by Sidney J. Frazer. Again, barring may be used to do this, although operators sometimes do this by careful manual manipulation of the valves.Valve manipulation is shown in [http://www.newsm.org/steam-engines/harris1_left.jpg this photo] from the [http://www.newsm.org New England Wireless & Steam Museum]
For large engines, muscle powered barring is sufficiently difficult that barring engines are frequently installed.Walter S. Hutton, [https://books.google.com/books?id=U39MAAAAMAAJ The Practical Engineer's Handbook], Crosby, Lockwood and Son, London, 1892, pages [https://books.google.com/books?id=U39MAAAAMAAJ&pg=PA408 408] and [https://books.google.com/books?id=U39MAAAAMAAJ&pg=PA410 410] These are small engines with gear teeth cut to mate with the teeth on the flywheel. Generally, the drive gears of the barring engine are designed to automatically disengage if the engine begins running under its own power while the barring gears are engaged.
Company history
The Corliss Steam Engine Company was originally known as Fairbanks, Clark & Co. in the 1830s. In 1843 it was renamed Fairbanks, Bancroft & Co. when Edward Bancroft joined the company. In 1846 it was renamed Bancroft, Nightingale & Co. when George H. Corliss joined the company, and in 1847 it was renamed Corliss, Nightingale and Co. In 1848 the company moved to the Charles Street Railroad Crossing in Providence, Rhode Island.
In 1857 the company was renamed for the last time to Corliss Steam Engine Company. By 1864 Corliss bought out his partners and was the sole owner of the company.
By 1859, all of the key features of what we now know as the Corliss engine were in place. Patents granted to Corliss and others incorporated rotary valves and crank shafts in-line with the cylinders. See, for example, Corliss' U.S. Patent 24,618, granted July 5, 1859.{{cite patent|country=US|number=24618|pubdate=1859-07-05|title=Steam-engine|inventor1-last=Corliss|inventor1-first=George H.}} Competing inventors worked hard to invent alternatives to Corliss' mechanisms; they generally avoided Corlis's use of a wrist plate and adopted alternative releasing mechanisms for the steam valves, as in Jamieson's U.S. Patent 19,640, granted March 16, 1858.{{cite patent|country=US|number=19640|pubdate=1858-03-16|title=Improved mode of operating valves in steam-engines|inventor1-last=Jamieson|inventor1-first=Thomas S.}}
Corliss' 1849 patent expired in 1870; the term of this patent had been extended by U.S. Patent reissue 200 on May 13, 1851, and U.S. Patent reissues 758 and 763 on July 12, 1859. B. Hick and Son were first to introduce the Corliss engine into the United Kingdom about 1864. After 1870, numerous other companies began to manufacture Corliss engines. Among them, the William A. Harris Steam Engine Company,{{cite web|author=Michael Thompson |url=http://www.newsm.org/steam-engines/harris-steam-engine-co.html |website=New England Wireless & Steam Museum |title=William A. Harris Steam Engine Co. |date=April 18, 2016 |access-date=16 October 2017}} the Worthington Pump and Machinery Company,{{cite web |title=Worthington Horizontal Cross-compound Pumping Engine |url=http://files.asme.org/ASMEORG/Communities/History/Landmarks/5660.pdf |access-date=16 October 2017 |archive-url=https://web.archive.org/web/20110812203012/http://files.asme.org/ASMEORG/Communities/History/Landmarks/5660.pdf |archive-date=2011-08-12}} and Allis-Chalmers.{{cite web |title=A Jacksonville, Florida Historic Mechanical Engineering Landmark |url=http://files.asme.org/ASMEORG/Communities/History/Landmarks/5634.pdf |access-date=16 October 2017 |archive-url=https://web.archive.org/web/20120314074314/http://files.asme.org/ASMEORG/Communities/History/Landmarks/5634.pdf |archive-date=2012-03-14}} In general, these machines were referred to as Corliss engines regardless of who made them.
In 1895 the company was shut down under the burden of $800,000 debt, and in 1900 it was sold to International Power Company controlled by industrialist Joseph H. Hoadley.{{Cite book |last=Armes |first=Ethel |url=http://archive.org/details/storyofcoalironi00arme |title=The story of coal and iron in Alabama |date=1910 |publisher=Birmingham, Ala., Pub. under auspices of the Chamber of commerce |others=The Library of Congress}} In 1905 it was transferred to another Hoadley's firm, the {{Interlanguage link|American & British Manufacturing Corporation|de}}.
In 1925 the company merged into Franklin Machine Company. By then Franklin Machine Company was already owned by the William A. Harris Steam Engine Company.
{{Asof|2024}} there are approximately six engines with the original slide-valve mechanisms still in existence, including one at 7 South Stone Mill Drive along Mother Brook in Dedham, Massachusetts.{{cite book | title = Mother Brook and the Mills of East Dedham | last = Neiswander | first = Judith | publisher = Damianos Publishing | year = 2024 | isbn = 978-1-941573-66-2|p=76}}
Centennial Engine
The Corliss Centennial Engine was an all-inclusive, specially built rotative beam engine that powered virtually all of the exhibits at the United States Centennial Exhibition in Philadelphia in 1876 through shafts totaling over a mile in length. Switched on by President Ulysses S. Grant and Emperor Pedro II of Brazil, the engine was in public view for the duration of the fair.
The engine was configured as two cylinders side by side. Each cylinder was bored to {{convert|44|in|cm|0}} with a stroke of {{convert|10|ft|m}}. The Centennial Engine was {{convert|45|ft|m}} tall, had a flywheel {{convert|30|ft|m}} in diameter, and produced {{convert|1400|hp|lk=in}}. After the fair it was disassembled and shipped back to Corliss's plant in Providence. Seven years later it was sold and powered a Chicago factory owned by George Pullman until 1910,{{cite web |author=Michael Thompson |date=January 13, 2010 |title=Corliss Centennial Engine |website=New England Wireless & Steam Museum |url=http://newsm.org/steam-e/corliss-centennial-engine/ |access-date=16 October 2017}} when it was sold as scrap.{{cite web |title=Some Engines! |url=http://www.150.si.edu/chap4/engine.htm |publisher=Smithsonian Institution |access-date=2009-11-14 |archive-url=https://web.archive.org/web/20100607074529/http://www.150.si.edu/chap4/engine.htm |archive-date=2010-06-07}}
This engine became a cultural icon, so much so that to many modern historians the term Corliss Engine (or Corliss Steam Engine) refers to this specific engine and not to the broad class of engines fitted with Corliss valve gear.{{cite book |first=John F. |last=Kasson |title=Civilizing the Machine: Technology and Republican Values in America |publisher=Macmillan |date=1999 |pages=162–167}} The Corliss engine at the Centennial exhibition is discussed entirely as a cultural icon.
{{Gallery
|title=Centennial steam engine
|align=center
|File:The Corliss 'Centennial Engine' at the US Centennial Exhibition (1876).jpg|The Centennial Engine at the U.S. Centennial Exhibition in Philadelphia, 1876
|File:Dompedro-grant.jpg|U.S. President Ulysses S. Grant and Emperor Pedro II of Brazil starting the Corliss Centennial Engine at the opening ceremonies of the Centennial Exhibition
|File:Corliss centennial steam engine model-IMG 5895-white.jpg|Model on display at the MIT Museum
}}
List of operational engines
File:Steam engine in Science Museum Power gallery.ogv, England, UK.]]
Notable people
See also
{{div col|colwidth=22em}}
- Corliss Steam Engine (Pawnee, Oklahoma)
- Piston valve
- Poppet valve
- Sleeve valve
- Slide valve
- Steam locomotive nomenclature
- Trip valve gear
- Valve gear
- Variable valve timing
{{div col end}}
References
{{Reflist|30em}}
- Popular Mechanics Monthly Magazine of April 1907, commented on page 416, near the bottom right of the page, the Corliss Engine can be made to do more work by raising the boiler pressure, increasing the speed or giving less laps to the steam valves.
External links
{{Commons category|Steam engines with Corliss valvegear|Corliss engines}}
- [http://www.wkinsler.com/technology/corliss/index.html Chapter 14 of Audel's Engineer's and Mechanic's Guide by Frank D. Graham].
- [http://www.newsm.org/steam-engines/corliss-steam-engine-co.html Corliss History] from the [http://www.newsm.org/ New England Wireless and Steam Museum].
- [http://www.cctsteam.50megs.com/corbasics.htm Corliss Steam Engine Basics] from the [http://www.cctsteam.50megs.com/ Stationary Steam Preservation] web pages of the [https://archive.today/20130101232952/http://ccthreshers.users2.50megs.com/ Camp Creek Threshers].
- [http://www.newsm.org/steam-engines/corliss-centenial.html Corliss Steam Engine Co. Centennial Engine] images at the [http://www.newsm.org/ New England Wireless and Steam Museum] website.
- [https://www.tripadvisor.com/LocationPhotoDirectLink-g49081-d143836-i112231669-Denton_Farm_Park-Denton_North_Carolina.html Denton Farm Park, Denton North Carolina]
- [http://www.gutenberg.org/files/8297/8297-h/8297-h.htm SCIENTIFIC AMERICAN SUPPLEMENT NO. 286 NEW YORK, JUNE 25, 1881: 1000 hp Corliss Engine] The Saltaire Engine, a Hick Hargreaves engine with illustrations.
{{steam engine configurations}}
{{DEFAULTSORT:Corliss Steam Engine}}
Category:Stationary steam engines