the lost motion in the rod and connections, so
the loose bolt does not strike the head; when shut off the piston
travels the extra amount of this lost motion and the bolt strikes the
head.

100. Q. When should cross-heads or guides be reported to be lined?

A. When there is excessive lost motion between the cross-head and the
top and bottom guides, or between the cross-head and the guide at the
sides, or when the piston rod is not central between the guides.

101. Q. When should driving box wedges be reported to be lined?

A. When they have been set up as far as possible and the boxes are still
loose between the wedge and shoe. At this time would also report any
excessive flange wear on any one particular tire.

102. Q. When should rod brasses be reported to be reduced? When to be
lined?

A. Rod brasses should be reported reduced when they are larger than the
pins and are pounding and cannot be keyed up properly. They should be
reported to be lined when the key has been drawn or driven to its full
length and the brasses do not close together or are too loose in the
strap lengthwise of the rod.

103. Q. When should lost motion between engine and tender be taken up?

A. When the lost motion becomes so great as to endanger the breaking of
connections.

104. Q. How do you proceed to pack a driving box equipped with a grease
cellar?

A. Remove the filling plate on the inside of the cellar. Pull down the
indicators and follower plates, insert the grease between the follower
plate and perforated plate; when full, replace the filling plate on the
inside of the cellar and allow the spring and follower plate to force
the grease through the perforated plate to the journal.

105. Q. Please explain the principle on which an injector works.

A. With a lifting injector the steam valve is opened a small amount to
furnish steam for the priming or starting jet. This forces the air in
the body of the injector and top end of suction pipe out through the
overflow valve, producing a partial vacuum in the body of the injector.
Atmospheric pressure in the tank then forces the water into the injector
body. When it begins to come out through the overflow, a further
movement of the steam valve opens the forcing valve wide, so a full
supply of steam strikes the water at a high velocity and at the same
time condensing. This action of the steam gives the water sufficient
velocity to overcome the boiler pressure and pass into the boile