EXAM PLES.
Lenoir Engine.— In a paper published by M. M. Lefevre of Paris in 1864 the following was stated: "The Lenoir engine uses the piston according to the patent of Street, it is direct and double acting as Lebon's engine, it is electrically ignited as that of von Rivaz, it can be operated by hydrogen as proposed by Herskine-Harzard, and one probably would recognize Talbot's splendid ideas in the slide valve as used by Lenoir. But the Lenoir engine draws in gas and air itself without previous mixing and that constitutes its patent claims.'' Lenoir's original engine was modeled after the standard steam engine, had a 3-inch bore, 5-inch stroke and a speed of 100 revolutions per minute. It was without a water jacket, had a continuously sparking ignition plug, located in the middle of the cylinder and laid bare by the piston, thus igniting the mixture in the front and back end alternately and giving off power during the sec ond half of the stroke only. Its fuel consump tion was high, and its over-all efficiency from 3 per cent to 4 per cent.
Otto and Langen Free Piston Engine.— Among the most zealous of those who tried to improve the gas engine was a young merchant, N. H. Otto of Cologne. Through experiments in 1861 and 1862 he learned that cooling the gases caused a great decrease in volume, and consequently a partial vacuum. Otto endeavored to use this for the generation of power. After many tedious experiments he and his partner, E. Langen, to whom we owe the systematic de velopment of this engine, succeeded in perfect ing an engine, shown in Figs. 53 and 54. The striking feature of this engine is the use of a free piston connected with the flywheel shaft, a, by means of rack, i, and pinion, o, which runs freely on the shaft while the piston is on its upward stroke, but, by an ingenious clutch ar rangement, it grips the shaft on the down stroke. The valve, e, by one in- and out-stroke, causes the exhaust, intake and explosion in the order named. It is moved by rod, d, connected to crank, r. The elastic connection, d, is unique and is worth notice. Levers f and g lift the piston and the charge enters through slide valve, e. After the piston has made a stroke
for 10 years, several thousands being con structed in that period.
Brayton Engine.— This engine is an Ameri can product and was introduced to the public by Brayton at the exhibition in Philadelphia in 1878. It is of the single acting, two cycle type with a working stroke at every revolution. Gas and air are compressed by a separate pump and then delivered to the motor cylinder where, on entering, they are gradually ignited by a con stantly burning flame. There is not an ex plosion but a combustion at constant pressure. At a certain point the supply of power is cut off and the hot gases expand to almost atmos pheric pressure before discharge. There is a wire gauze fixed behind the flame to prevent the flame from striking back into the charge pipe. If this happens a serious explosion fol of a few inches the valve, e, carries the ignition flame to the inlet port causing a sudden com bustion of the charge within the cylinder. The power developed drives the piston upward with a maximum velocity of over 2,000 feet per minute. Due to over expansion and cooling of the gases a vacuum is created below the piston, and, on the down stroke of the piston, work is done by the atmosphere and the weight of piston and rack. This free piston engine was exhibited at the Paris Exposition in 1867. Lay men were even afraid of the instantaneous ascent of the rack, and experts criticized se verely the awkwardness and noise of the engine. After a competitive test with 14 other gas engines, in which it showed an over-all effi ciency of 15 per cent, opinions suddenly changed. It completely crushed Lenoir, and held almost the sole command of the market lows, stopping or wrecking the engine. On this account Brayton abandoned the use of gas and substituted light oils. Although the danger of explosion was thus removed, new difficulties arose due to the rapid accumulation of soot in the cylinder which cut the latter. A great num ber of Brayton• engines have been built by the Ready Motor Company of New York The over-all efficiency of this engine was about 6 per cent.