...Railway artillery - Personal Page of GENE SLOVER

695
667. The diagram makes no allowance for curv(>s. but it is safe for
"quipment .whose truck centers do not exceed 40 feet. On railway
mounts whose trucks centers exceed this dimension, allowance must
be made for the overhang of the mount in rounding curves. It is
safe to figure a maximum curve of 17 degrees, 337 feet radius, on the
main lines of railroads shown. Hence, the width of the mount wilt
be reduced at least as much as the computed off-set on a 17-degree
curve. A full discussion of railroad curves will be given later.
668. It was early recognized that to compile a clearance diagram
of every railroad system in the country would be an endless and
indeterminate task as well as being worthless when completed. The
futility of attempting to establish such an absolute clearance diagram
of every road is best illustrated by the following facts: There
are over 250,000 miles of railroads in America. Some of these roads
are inaccessible to any but the lightest railway equipment and are
.located in the interior mountainous regions. For instance, some
standard gauge railroads are used only by the lumber interests.
Special logging cars and locomotives comprise the rolling stock of
these roads. Obviously no piece of railway a.rtillery could ever be
transported over such tracks. Such roads would therefore be useless
for railway artillery shipments and have not been considered.
669. Other railroads, while using standard equipment, touch only
the small central and western interior towns. These roads are generally
branches of the larger systems and it is improbable that any
emergency could ever arise for their use. If it did, the branches would
have to be rebuilt. These roads are not considered on the diagram.
670. To compile a maximum clearance diagram of all the big railroad
systems of the country would result in such limitation of dimensions
of the railway mount that one could not lise it for the design of
the heavier caliber guns. The branch lines of some of these systems
present limitations that sometimes interfere with their. standard equipment,
but the territory covered is so important that lighter rolling
stock is used. Hence it would be unwise to limit the diagram by including.
all branch lines of the big systems. Some of the branch
lines, however, are of vital importance and these have been included.
If it is not possible to reach an important point from one line on
account of some limiting feature, it has generally been found possible
to detour to that point.
671. It must not be presumed from this discussion that railway
clearances can be compiled into a fixed outline or diagram. The
more progressive railroad companies are constantly changing their
clearances and improving their curves. So to keep up to date, it is
necessary to keep in touch with the railroad engineers. These
changes should be checked up (>v(>ry six months and the diagrams
changf'd if a1f(>ctf'd.
Digitized by Coogle