The workingman's advocate. [volume] (Chicago [Ill.]) 1864-1877, 1870-06-04

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"Comuound" VI. Single Engines

- 0 FcOR the American Artisan.
Compound W. single Engines
It hcH bat ELEVEN yesal %, . century
since Jonathan Honblower claimed that
BY the use Of second Or expansion cylin-
der Be would secure advantageous results.
as compared Vhh those given BY Watts
engines, IN the ratio Of three to vWp and
sixty Yeas have elapsed 6Ace Wolfe. with
more of scientific data for his guidance,
embodied the expausion pEineiPle in the
engine which bears his name. 1t takes O
kiosE dina, hoRevsr, to settle the coalitions
best suited to the working of any given
system ufueChanism, AID k need be a mat
ter of no surprise that the relative merits of
compound and single engines are still q
subject of discussion. The question has
been trcated pro and sen.. under the head
Of" Economical Steam Engines, in articles
published in previous numbers Of our jour
nal, and is the subject Of an editorial in a
recent number Of the Engineer, the con-
illusions of which furnish q digest of the
main points of the matter.
The writer starts with the common-sense
assumption that the economy Of an engine
should be estimated not alone from the
quantity Of coal consumed, but from the
total expenditure incurred for fuel, repairs,
fabrication, and incidents. Tried BY this
standard, compound engines will afford ex-
cellent results when steam Of very high pres
sure il used An example of this is found
in an engine now running in the Perkins
establishments in London The boiler carries
a pressure Of SIX hundred pounds to the
square inch. The total admisgon Of steam
to the eyIadsr.i is for three inches Of the six
inch stroke of the piston. The engine has
three cylinders, and has indicated one hum
drsd horsepower under thsse ceadit5oAs, the
vacaa being n iaObes. ! With engines pro
perly made. and used with from two hun
bred and fifty to Eve hundred pounds, or
even higher pressure, compromising may be
considered advisable On the other hand,
with the pressures below forty pounds for
marine, and one hundred for stationary
motors, the simple engine will be found to
give the best results This is shown BY the
failure Of compound engines at such COM
paratively low pressures to compete in econo-
my with The single cylinder engines, and the
fact that in some cases-for example, that
Of the skeamWs MO,atas, Of The II @insalar
and Oriental Line-the former have been
discarded and replaced by the latter. The
measure Of expansion, Of course, bears
directly upon the question, and the writer
referred to intimates that unless the steam
b cut of at less than one-tenth, no neces-
sity for compromising Win be involved. The
ebjsc6on that for irregular work, or, in
other words, varying resistance, the single
will be less steady than the compound en-
gina is met by he suggestion Of . heavy
Ay.vheel, as preventive Of such unsteadi-
ness. bsing much cheaper than tia gaining
Of the same end through the agency Of an
expansion cylinder, and as having none Of
the liability ". get out of order incident to
the sdditi6n4f comple1hy Of . compound
engine. As to the mischief likely to occur
from the shock Of high steam On large
piston, proportiOnats strength Of parts win
not cost as much as second cylinder; or
if this method Of meeting the difficulty ID
not approved, small pist0ns making mo
derste number of revolutiens per minute,
but having rapid speed with long stroke,
may be employed to avoid Che necessity Of
changing. at high speed. the direction Of
the moving parts, wherein lies the true
source Of trouble o. the character Just in
dicated. This is done on several American
steam vessels with beam engine, q type re-
favorable to great piston speed, but in
which, from high speSd sem6ined with .
small number Of reyslu6ons,s great and
economic power Is obtained. While, there
fore, the high, Pressgres, advocated by
Wolfe, Perkins, and others in the infancy
Of steam engineering may necesitate the |
use of the compound principle Of engine
building, the more common prsssures of
one huadred per inch or less will give the
most profit when employed with single
cylinder engines having small pistons,
high speed, long Strokes, medents number
sf revolutions per minute, end heavy n.y.
wHeeis TO -equalizs the motion agsinst re- |
sistance OfSaryiue degree. n =
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