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Oliver Evans (13 September 1755 – 15 April 1819) was an American inventor. He was born in Newport, Delaware, to a family of Welsh settlers. His parents were Charles and Ann Stalcop Evans.
At the age of 14 he was apprenticed to a wheelwright.
Evans' first invention was in 1777, when he designed a machine for making card teeth for carding wool. He went into business with his brothers and produced a number of improvements in the flour milling industry.
Evans devoted a great deal of his time to patents, patent extensions, and enforcement of his patents.
Evans began experimenting with steam power, and in 1783 applied for a patent for a steam-powered wagon. This was not granted, in the absence of a working model. In 1787 Evans held a Grant from the Legislature of Delaware for the sole use in the State of steam carriages on common roads. 
In the early 1780s Evans turned his attention turned to flour milling, a field in which he produced remarkable advances.
Evans began to focus in earnest on the use of high pressure steam, and invested much time and money to produce a working steam engine, which he displayed in 1803. It had a double-acting cylinder of 6" bore, with a piston stroke of 18". Many components were made of wood. The boiler consisted of a large copper shell encased in wood and and bound by iron rings. The output was approximately 5 HP. For comparison, the low-pressure engine of the nearby waterworks produced about 12 HP, but its cylinder volume was over twenty-five times that of Evans's. Evans set his engine to work at his shop, crushing plaster of Paris and sawing slabs of marble. He received a patent for his engine in 1804.
In 1805 Evans convinced the Philadelphia Board of Health to contract him to develop a steam-powered dredge. The vessel, the Oruktor Amphibolos, or "Amphibious Digger", was a flat-bottomed scow with a bucket chain dredging system. Power for dredging and propulsion was supplied by a high-pressure Evans engine of 5" bore and 19" stroke. The vessel was 30 feet long, 12 feet wide and weighed about 17 tons. Evans mounted the hull on four wheels and connected the engine to them in order to drive the Oruktor from his workshop through the Philadelphia streets on the way to the Schuylkill River on July 13, 1805. The Oruktor Amphibolos is believed to have been the first self-propelled steam vehicle in the USA, and the first powered amphibious craft in the world. However, very few contemporary accounts of the craft survive, and Evans's tendency to exaggerate its success make verification of its performance difficult. Evans claimed that it proceeded successfully around Philadelphia before launching into the river and paddling at speed to Philadelphia harbour. However the great weight, challenges regarding power transmission to the wheels, and steerability of such a craft make land-propulsion somewhat improbable over any significant distance. It is unknown how well, if at all, the Oruktor functioned as a steamboat, and Evans's claims on this point vary significantly over the years. Nevertheless, it is known that the invention proved ineffective as a dredger, and it was scrapped for parts by the Board of Health in 1808. Subsequently, Evans wrote about the Oruktor in many publications, and each time the claimed achievements became more impressive. He also 'corrected' the date of the machine from 1805 to 1804, possibly in a dispute about steamboat patents.
In 1812 he published a futuristic description of a world connected by a network of shipping lines, railways, and steam locomotives. He wrote: "Carriages powered by steam will come into universal use, and travel at the rate of 300 miles per day."
Evans frequently quarrelled with fellow inventors and engineering peers over steam technology in the mid-1800s. His increasing frustration led to his publication in 1805 of what he had hoped would be the equivalent of his earlier manual for millers — The Abortion of the Young Steam Engineer's Guide. One third of the book is devoted to an ongoing argument between Evans and John Stevens. The Steam Engineer's Guide proved to be a popular work, though not on the same scale as his guide to milling. It was the first book in the United States to make ideas and techniques for steam engineering readily accessible to anyone. It was also published in translation in France (second edition published in 1825). Transcribed version (in English) .
Evans's early high pressure steam engine developments were contemporary with those of Richard Trevithick in England, but it is improbable that they were aware of each other's work. Trevithick's high pressure boilers and engines were introduced slightly ahead of Evans's, Trevithick installing his first high pressure engines in 1800. Both engineers saw the benefits offered by high pressure steam in terms of providing a compact source of power, suited to the needs of locomotion. Both Trevithick and Evans favoured pre-heating of the boiler feed water, and the use of boilers with internal flues. Trevithick preheated his feed water using an exhaust steam heat exchanger, while Evans had a preheater heated by the flue gases leaving the boiler. This can be seen in Drawing (3) above (from the 1825 French version of Evans's 1805 Manual). The engine's drop valves were operated by cams. It is clear from the text that Evans was aware of the advantages of expansive working (by early cut-off of the steam supplied to the cylinders).
In 1811, Evans founded the Pittsburgh Steam Engine Company, which in addition to engines made other heavy machinery and castings in Pittsburgh, Pennsylvania. The location of the factory in the Mississippi watershed was important in the development of high pressure steam engines for the use in riverboats.
Evans produced the first detailed and theoretically coherent design for a vapour-compression refrigerator, identifying all the major components of a refrigeration cycle. Although Evans never developed a working model of his designs, and there is no evidence that he ever attempted to, in his later life he worked and associated extensively with Jacob Perkins on steam engines and on the potential for refrigeration. Perkins would later develop and build a refrigeration device for which he received patents in 1834–1835, employing much the same principles originally put forward by Evans.
Mars Works, 1806–12
Evans constructed the Mars Works on a large site in Philadelphia. It was one of the largest and best equipped factories of its kind in the USA, and produced a wide range of products including steam engines, iron castings, milling equipment and agricultural machinery, caannon, etc. For a woollen mill in Middletown, Connecticut, Evans designed a network of accompanying pipes with radiators to heat the factory with engine exhaust.
In 1812 the Mars Woks produced the Columbian Engine, a horizontal engine with the piston rod guided by what became known as the Evans straight-line linkage, though it was superseded within a few years by more precise straight line mechanisms. In 1813 he introduced a condenser to the Columbian design. Within a year 27 Columbian engines were operating or under construction in applications ranging from sawmilling and grain milling to the manufacturing of paper, wire and wool.
Evans is best known for the system of conveyors and other equipment he developed for his highly-automated flour mill which operated continuously through the use of bulk material handling devices including bucket elevators, conveyor belts, and Archimedean screws. Evans described this invention in The Young Mill-wright and Millers' Guide. He patented this invention in a few states and, when the US patent system was established, in the federal patent system (Third U.S. Patent).
Evans' description of his fully automatic flour mill:
"These five machines…perform every necessary movement of the grain, and meal, from one part of the mill to another, and from one machine to another, through all the various operations, from the time the grain is emptied from the wagoner's bag….until completely manufactured into flour…without the aid of manual labor, excepting to set the different machines in motion."
The Evans material handling system became widely used in flour mills and breweries during the 19th century.
See Wikipedia entry for much more information.
David Hounshell (1984) acknowledged the influence of Evans' automatic flour mill in the sequence of innovations leading up to the assembly line.
In 1819, while in New York City, Oliver Evans was informed that his workshop in Philadelphia had burned to the ground. Evans suffered a stroke at the news, and died soon after. He is buried in Trinity Cemetery, Broadway at 154th Street, New York City