The Traveling Engineers Association | Page 8

as rapidly as in the center of the fire-box; always fire as light as
consistent with the work required, endeavor to maintain a uniform
steam pressure at all times, and avoid unnecessary black smoke and a
waste of steam through the safety valves by the engine popping.
2. Q. What are the advantages of superheated steam over saturated
steam in locomotive service?
A. Saving in water; saving in fuel; increased boiler capacity and a more
powerful locomotive. Superheated steam does away entirely with all
condensation in the cylinders, while saturated steam coming in contact
with passages in cylinder saddle and walls of cylinders, is immediately
cooled and in cooling, a part of it is changed back into water which
affects the pressure and therefore its capacity to do work.
3. Q. How is the saving in water produced?
A. By the elimination of all cylinder condensation present in saturated
steam locomotives and the increase in volume of a given weight of
steam.
4. Q. How is the saving in coal accomplished?
A. Because there is less steam used to do the same amount of work,
there is less water evaporated and consequently less coal required to
evaporate the water.
5. Q. How is the increased boiler capacity obtained?
A. A boiler will evaporate a certain amount of water into steam and if
part of the steam is lost by condensation, only that remaining is
available for running the engine. Superheating eliminates the losses,
thereby increasing the available useful steam. Further, superheating
increases the volume of a given weight of steam, thereby reducing the
consumption of steam required to develop a certain power and
consequently increases the capacity.

6. Q. How is a more powerful engine obtained?
A. By reason of the increased boiler capacity an engine may be worked
farther down before a steam failure occurs.
7. Q. What type of fire tube superheater is in most general use in
locomotive service?
A. The top header fire tube type, known as the "Schmidt Superheater."
A system of units located in large flues through which the steam passes
on its way from the dry pipe to the steam pipes, and a damper
mechanism which controls the flow of gases through the large flues.
8. Q. Describe the construction and location of the header.
A. The header is a simple casting, divided by partition walls into
saturated and superheated steam passages. It is located between the dry
pipe and the steam pipes, the same as the nigger head in a saturated
locomotive. The dry pipe is in communication with the saturated steam
passages and the steam pipes with the superheated steam passages and
these are in communication with each other through the superheated
units.
9. Q. Describe the construction of superheater units and their
connection to the header.
A. The units are composed of four seamless steel pipes, connected by
three return bends. Of the four pipes, two are straight and two are bent
upward and connected to the header by means of a clamp and bolt; one
end of the unit is in communication with the saturated steam passage
and the other with the superheated steam passage in the header casting.
10. Q. Trace the flow of steam through the top header fire tube
superheater.
A. When the engine throttle is open, saturated steam passes through the
dry pipe into the saturated steam passage of the header casting. From
this passage it enters one end of the unit, passing backward toward the

fire-box, forward through one of the straight pipes and the front return
bend, backward through the other straight pipe to the back return bend,
and forward through the bent pipe and upward into the superheater
steam passage of the header, from which it enters the steam pipes and is
carried to the steam chest.
11. Q. What should be the position of throttle valve when running a
superheater locomotive?
A. The engine should always be run with as wide open throttle as the
conditions will permit, regulating the steam admission to the cylinders
according to work to be performed.
12. Q. What should be the position of throttle while drifting?
A. The throttle valve should be kept slightly open while drifting, so as
to admit a small quantity of steam in valve chamber and cylinder above
atmospheric pressure, to prevent the inrush of hot air and gases which
destroy lubrication, also to prevent excessive wear to valve, cylinder
and piston rod packing.
13. Q. How should the water be carried in boiler of superheater
locomotives?
A. As low as the conditions will permit, because this practice reduces
the tendency to work water over into the dry pipe and units, as the
superheater locomotive will use one-third less water than the saturated
locomotive.
14. Q. What care should be exercised in lubricating