Scientific American Supplement, No. 458, October 11, 1884Various
Science
Scientific American Supplement, No. 458, October 11, 1884
Various
Science -- Periodicals
Following these, others of the leading railways took up the system, and
prominently among these Mr. Worsdell, of the Great Eastern Railway, built
a number of large express engines for his fast and heavy traffic, and is
now building a number of others similar as to the valve gear for his
suburban traffic, which is specially heavy. Also the Lancashire and
Yorkshire and the Midland and others of the chief railways are employing
the system specially for large express engines; the Midland engines having
cylinders of 19 inches diameter by 26 inches stroke, and four coupled
wheels of 7 feet diameter. A number of the above-named engines have run
large mileages, in many cases already exceeding 100,000 miles per engine.
For other countries also a number of locomotive engines have been built or
contracted for--both of inside and outside cylinder types--making a total
of nearly 800 locomotives built and building, many of them being of
special design and large size, up to 20 inches and 21 inches diameter of
cylinder.
In all these the absence of wire-drawing may be specially noted by the
full line at the top of the diagram, showing the admission of steam--this
fullness arising from the rapid and full opening of the port for
admission.
Passing now to the other great type of engines, those covered under the
general designation of marine engines, this gear has been applied to
nearly 40,000 H.P. indicated, built and building, and to all classes and
sizes, from the launch engine with cylinders 8 inches by 9 inches, running
at 600 to 700 revolutions per minute, up to engines for the largest class
of war ships, such as her Britannic Majesty's steel cruiser Amphion, of
5,000 H.P., with cylinders in duplicate of 46 inches and 86 inches
diameter, and 3 feet 3 inches stroke, running 100 revolutions per minute.
An examination of the indicator diagrams taken from these engines shows
that no wire-drawing takes place, and that, though the expansion is
carried to a point beyond the ordinary requirements, the compression is
but slightly increased. In all the diagrams taken from this valve motion
there is seen the clear, full upper line showing an abundant admission of
steam without any wire-drawing, and also the distinctly marked points
where "cut-off" or "suppression" and where "release" takes place, showing
the rapid action of the valves at those points.
It is well known to engineers that to obtain the maximum advantage out of
compounding, it is necessary to cut off in the low pressure cylinder at a
point corresponding to the relation between the low and the high, and that
point should be unaltered, whereas the point of cut-off in the high may at
the same time be varied to suit the work to be done.
Public-domain text, read in full here on John Shaqi.
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