oliver evans invented the high pressure steam engine in the us independently of trevithick.
oliver evans invented the high pressure steam engine in the us independently of trevithick.
who invented the high pressure steam engine in the us independently of trevithick?
oliver evans
evans had first begun to consider the potential applications of steam power for transportation while still an apprentice in the 1780s, and had developed rudimentary designs for 'steam carriages' in the 1790s. in 1801, evans definitively began work on making his long-held dream of a steam carriage into reality. early steam engineers, most notably watt contemporary william murdoch, had developed plans for a steam-propelled carriage incorporating a heavy flywheel, in which pressure was converted directly to rotary power, however it became apparent in experimentation that a low-pressure, rotary steam engine would never be powerful enough to propel a carriage of any weight forward. evans's attention thus turned to a reciprocating engine, not only for his steam carriage ideas, but also for industrial application. importantly, evans became an early proponent of 'strong steam' or high-pressure engines, an idea long resisted by watt and earlier steam pioneers because the necessary iron making and metal working technology was lacking. evans recognized that a high-pressure steam engine would be essential to the development of a steam carriage because they could be built far smaller while providing similar or greater power outputs to low-pressure equivalents. some experiments with high-pressure steam engines had been made in europe, most notably an unsuccessful steam tractor developed by nicolas-joseph cugnot. however the prevailing fear of early steam engineering was that no boiler could safely contain high-pressure steam. evans ignored potential drawbacks, and developed radically different designs which called for engines operating at high-pressure and the elimination of the condenser—a central component of conventional designs. his designs also incorporated a grasshopper beam, a double-acting cylinder, and four steam valves. each valve was independently operated by one of four cams. the resulting design was a high-pressure steam engine that had a higher power-to-weight ratio that prevailing designs, making locomotives and steamboats practical. it was also mechanically simpler than condensing engines, making it less costly to build and maintain, and did not require large volumes of condensing water. these features would make it similarly suited for a variety of industrial applications.
oliver evans
the cornish engine depended on the use of steam pressure above atmospheric pressure, as devised by richard trevithick in the 19th century. trevithick's early "puffer" engines discharged steam into the atmosphere. this differed from the watt steam engine, which moved the condensing steam from the cylinder to a condenser separate from the cylinder; hence watt's engine depended on the creation of a vacuum when the steam was condensed. trevithick's later engines (in the 1810s) combined the two principles, starting with high-pressure steam which was then passed to the other side of the piston, where it condensed and there it acted as a sub-atmospheric pressure engine. in a parallel development arthur woolf developed the compound steam engine, in which the steam expanded in two cylinders successively, each of which were at pressures above atmospheric.
cornish engine