The proper and accurate setting of a valve on a steam engine is one of
the most important duties that you will have to perform, as it requires
a nicety of calculation and a mechanical accuracy. And when we remember
also, that this is another one of the things for which no uniform rule
can be adopted, owing to the many circumstances which go to make an
engine so different under different conditions, we find it very
difficult to give you the light on this part of your duty which we would
wish to. We, however, hope to make it so clear to you that by the aid
of the engine before you, you can readily understand the conditions and
principles which control the valve in the particular engine which you
may have under your management.
The power and economy of an engine depends largely on the accurate
operation of its valve. It is, therefore, necessary that you know how
to reset it, should it become necessary to do so.
An authority says, "Bring your engine to a dead center and then adjust
your valve to the proper lead." This is all right as far as it goes, but
how are you to find the dead center. I know that it is a common custom
in the field to bring the engine to a center by the use of the eye. You
may have a good eye, but it is not good enough to depend on for the
accurate setting of a valve.