reciprocating engine

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reciprocating engine

[ri′sip·rə‚kād·iŋ ′en·jən]
(mechanical engineering)

Reciprocating Engine


a device in which a piston performs the basic function of transforming the energy of a working fluid. As the piston moves within a cylinder, there is a change in the volume of the chamber formed; as this occurs, various parameters of the working fluid, such as pressure and temperature, also change. During operation of a reciprocating engine, the energy of the working fluid may be decreased, as in a gasoline engine, or increased, as in a pump or compressor. The intake and exhaust of the working fluid in the cylinder are regulated by a distribution or timing mechanism using simple valves or slide valves or by the piston itself, as in a two-cycle engine.

The reciprocating engine is characterized by cyclic reoccurrence and intermittence of operation. In most reciprocating engines the piston is connected with the crankshaft by a crank gear, by means of which the reciprocating motion of the piston is converted into the rotary motion of the shaft, or vice versa. Because of the cyclic reoccurrence of operation and the presence of a crank gear, reciprocating engines do not operate at speeds as high as those achieved by rotodynamic machines; the former have a greater specific mass and greater factional losses. Reciprocating engines without connecting rods are now being used, in which reciprocating motion is converted to rotary motion by a powered mechanism without connecting rods. Rotary-piston engines, such as the Wankel engine, are also being used. In a steam pump, the reciprocating motion of the piston of a reciprocating engine is used directly to drive the pump’s piston; in a motor-driven compressor, the engine and compressor are combined in a single multicylinder unit. The use of a plunger as a piston in reciprocating engines makes it possible to operate pumps at higher pressures. Reciprocating engines are simple to operate, economical, reliable, and have a long operating life.


reciprocating engine

An engine that converts the chemical energy in the fuel plus air into mechanical energy by providing reciprocating movement to the pistons. This movement is further converted into rotary motion by the connecting rods and crankshaft. A reciprocating engine is usually a four-stroke engine. See four-stroke cycle.
References in periodicals archive ?
While a little less than half of lead emissions from piston-engine aircraft linger near airports, the remainder disperses far and wide during flight, according to the EPA.
The lawsuits and the potential for regulation combined with concerns about rising avgas prices, declining use of piston-engine aircraft that burn the fuel, and the future of TEL supplies, which come from a single manufacturer, convinced the aviation industry that the time had come to find an alternative to 100LL, says Rob Hackman, vice president of regulatory affairs at the Aircraft Owners and Pilots Association (AOPA).
At a minimum he says the agency expects to certify a version of the current 100LL fuel with the lead removed (resulting in a reduced rating of 91-94 octane), which would satisfy a good chunk of the piston-engine fleet.
piston-engine fleet--around 75% is the number generally accepted by the industry, according to White--does not require high-octane avgas at all.
This gasoline-powered engine, the HeS 3, was flight-tested while slung beneath a piston-engine Heinkel airplane.
More than 20 months after the Heinkel flight, the British effort finally got off the ground, literally, having been hindered at first by more official disinterest (the Ministry was still more concerned with manufacturing enough piston-engine combat aircraft to fight the Battle of Britain and to replace those lost fighting the Battle of France) and then slowed by bureaucracy.
The name was flashy but a bit misleading: the plane could barely fly over 400 mph, slower than its piston-engine brethren.
In its ANPRM, the EPA requests public comments on the data available for evaluating lead emissions, ambient concentrations and potential exposure to lead from the continued use of leaded avgas in piston-engine powered aircraft.
The ANPRM's comment period extends through June 28, after which the agency likely will spend substantial time evaluating its research and "to conduct a risk assessment evaluating the potential contribution of lead from piston-engine emissions on blood lead levels and IQ deficits for those living near or attending school near general aviation activity.
According to the EPA, "lead emitted by piston-engine aircraft operating on leaded avgas is the largest source of lead to the air, contributing about 50 percent" of airborne lead.
A looming problem for lightplanes is that they are the country's sole users of leaded gasoline, and the quantity of 100-octane fuel consumed by our tiny fleet of 300,000 piston-engine airplanes - many of which fly fewer than 50 hours a year - is barely worth refining.
Which pretty much describes the fuselage of a piston-engine lightplane in flight.