This engine had
cylinders of 18 inches in diameter and 24 inch stroke, and six wheels
coupled 5 feet 1 inch diameter, and was designed by Mr. Webb, the
Company's chief engineer, for their heavy fast goods traffic on the main
line. The engine has been running this class of traffic ever since. In
January, 1884, it was passed through the repair shops for a general
overhauling, when it was found that the valve motion was in such good
condition as to be put back on the engine without any repairs.
The main object of this present paper is to deal with the advantages of
the valve gear and its application to various classes of engines both on
land and at sea, and with the results of such applications, rather than
treating it as a novelty, to give an exhaustive description of its
construction and functions, which was done in the paper above referred to.
A very short description of its action and main features will, however,
be necessary to the completeness of the paper, and as a basis from which
the improved results to be recorded should necessarily be shown to spring.
The essential feature of this valve gear is that movement for the valve is
produced by a combination of two motions at right angles to each other;
and by the various proportions in which these are combined, and by the
positions in which the moving parts are set with regard to each other, it
gives both the reversal of motion and the various degrees of expansion
required.
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