ss 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 a superheater
locomotive?

A. The supply of oil to steam chest should be watched very closely by
the engineer, he to know that lubricator is feeding constantly and
evenly over entire division, and according to work performed.

15. Q. Describe the general form of a locomotive boiler.

A. A locomotive boiler is cylindrical in form, it usually has a
rectangular shaped fire-box at one end and a smoke-box at the other, and
flues extend through the cylindrical part, and, like the fire-box, are
surrounded by water.

16. Q. How do