Improvements in Locomotive and other Multitubular Boilers.
Year: 1896

page_text: Date of Application, 12th June, 1896-Accepted, 12th June, 1897
COMPLETE SPECIFICATION.
Improvements in Locomotive and other Multitubular Boilers.
We, JOHN BRUNLEES, of 12 Victoria Street, Westminster, in the County of London,
Engineer, and JOHN WALKER, of 111. Osborn Road, Newcastle-on-Tyne, Engineer,
lo hereby declare the nature of this invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement :--
Our invention relates to an improved construction of the fire tubes of locomotive,
marine, and other multitubular boilers, whereby these are made to afford a greater
amount of heating surface at the end of the boiler farthest away from the fire box or
furnace and, at the same time, effect a reduction of the volume of comparatively cool
water at that end of the boiler.
For these purposes according to our invention we increase the diameter of the
tubes from the fire box or furnace end towards the smoke box or chimney end, thus
increasing the heat transmitting surface thereof at that part of the boiler where the
water is cooler, and at the same time decreasing the volume of such cooler water
between the tubes.
By this arrangement, we not only obtain a much more effective transmission of the
heat of the combustion gases to the water of the boiler, but we are also enabled to
make the boilers of greater length than heretofore, the length of the boilers as at
present constructed being practically limited by the large volume of comparatively
cool water that would otherwise be uselessly contained in the front or smoke box end
of the boiler.
The enlargement of the tubes can be effected either in one or more steps, as at
Fig. 1 of the accompanying drawing, where the fire tube A is shewn, by way of
example, with two steps, the part a next the fire box B being made cylindrical up to
the first step a', the intermediate part a² being made somewhat larger up to the
second step a³ and the part a', next the smoke box C, being made still larger.
The tube may of course be made either with only a single step, or with three or
more steps. Instead of enlarging the tubes in steps as described, they may be made
with a continuous taper as shewn at Fig. 2, the smaller end being at the fire box B
from which point it increases gradually in size towards the smoke box C. Or again,
the tube can be made taper up to a certain point of its length, where it is enlarged by
a step, the remaining portion of larger diameter being either made uniform throughout
or made to taper to a still larger diameter at the smoke box end. Or the front part
can be made of uniform diameter up to the step, and the smoke box end made to
taper to a larger diameter. When making the tubes of tapering diameter the taper
may either be uniform throughout or it may be made to vary, so that the outer
surface of the tube will present a concave or convex curvature.
Our invention is applicable not only to boilers of the locomotive type as at Fig. 3,
where the smaller ends would be at the fire box B, but also to marine boilers as at
Fig. 4 where the smaller ends would be at D in the combustion chamber and to all
other multitubular boilers, whether the tubes be horizontal, inclined, or vertical.
Fig. 5 shews a multitubular boiler with vertical tapering fire tubes A, the smaller
ends of which are at E.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed, we declare that what we
claim is :-
Constructing locomotive and other multitubular boilers with fire tubes the diameter

page_text: of which is made to increase, either gradually or in steps, or both gradually and in
steps, from the fire box or furnace end to the smoke box or chimney-end, substantially
as described.
ABEL & IMRAY,
Agents for the Applicants.