Farm engines and how to run them; the young engineer's guide with special attention to traction and gasoline farm engines, and a chapter on the science of successful threshing (1910) (14763015954)

Identifier: farmengineshowto00step (find matches)
Title: Farm engines and how to run them; the young engineer's guide ... with special attention to traction and gasoline farm engines, and a chapter on the science of successful threshing
Year: 1910 (1910s)
Authors: Stephenson, James H
Subjects: Farm engines Traction-engines
Publisher: Chicago, F.J. Drake & Co.
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress



Text Appearing Before Image:
e. There is a single plate betweenthem called the center head, and the same piston rod isfitted with two pistons, one for each cylinder. Thesteam chest does not receive steam from the boiler, butfrom the exhaust of the high pressure cylinder. Thesteam from the boiler goes into a chamber in the doublevalve, from which it passes to the ports of the highpressure cylinder. At the return stroke the exhauststeam escapes into the steam chest, and from there itpasses into the low pressure cylinder. There may beone valve riding on the back of another; but the simplestform of compound engine is built with a single doublevalve, which opens and closes the ports for both cylin-ders at one movement. Theoretically- the compound engine should effect a 6C0NQMY RUNNING FARM ENGINE. 1^3 genuine economy. In practice there are.many things tooperate against this. Of course if the steam pressure;S low to start with, the amount of pressure lost in the(rxbaust will be small. But if it is very high, the saving
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126 YOUNG engineers GUIDE. in the low pressure cylinder will be relatively large. Ifthe work can be done just as well with a low pressure, itwould be a practical waste to keep the pressure abnor-mally high in order to make the most of the compoundengine. An engine must be a certain size before the savingof a compound cylinder will be appreciable. In thesedays nearly all verydarge engines are compound, whilesmall engines are simple. Another consideration to be taken into account is thata compound is more complicated and so harder to man-age; and w^hen any unfavorable condition causes loss itcauses proportionately more loss on a compound than ona simple engine. For these and other reasons compoundengines have been used less for traction purposes thansimple engines have. It is probable that a skilled andthoroughly competent engineer, who would manage hisengine in a scientific manner, would get more out of acompound than out of a simple; and this would be espe-cially true in regions w^her