Q. How is a locomotive or fire box boiler constructed?
A. The ends of a cylindrical shell are continued straight down upon
the sides, and enclosed to form a rectangular structure in its lower
portion and conformed to the curvature of the cylindrical shell at the
top. In the rectangular portion is secured a fire box, separated from
the sides and ends by water spaces called “water legs,” and having
its top which is called the “crown sheet” about the center of the
cylindrical shell. An opening is formed in both sheets in rear end of
the fire box door frame. The cylindrical shell has heads riveted at
both ends. These heads have numerous flues open at both ends put in.
All the flat surfaces are stayed to each other at suitable intervals,
and the crown sheet is stayed from the shell. The fuel is thrown in
through the door at the rear, and the products of combustion are
conveyed to further extremity through the tubes or flues. It is
furnished with hand-holes for cleaning and a steam dome. There are two
different styles of fire boxes on Locomotive Boilers, the round bottom
fire box in which the water circulates under the grates, and the square
open bottom fire box. Both kinds are used extensively.
[Illustration: Freeman Locomotive Boiler.]
[Illustration: Sectional View Freeman Locomotive Boiler.]
Q. What advantages have the locomotive or fire box boiler?
A. It is entirely self-contained, generates steam very rapidly, is
economical in space, and needs no elaborate foundation.
Q. What disadvantages has the locomotive or fire box boiler?
A. Expensive first cost, and difficulty in cleaning, especially where
impure feed water is used.