rm its functions, it is
unquestionably necessary that it have power largely in excess of the
work required of it, and also that the friction shall represent a very
low percentage of that power. In respect to this, especial means have
been employed to reduce the friction; the valve being balanced,
requires but little power to move it, while the governor ball being made
heavy for the purpose of counterbalancing the weight of the eccentric
and strap, its centrifugal force when the engine is at full speed is
enormous, the spring to counteract it having to sustain from _two to
three thousand pounds_. Under these circumstances, as might be expected,
the regulation is remarkably good. This is a very important
consideration in an engine working under the conditions of a roll-train
engine.

[Illustration: Fig. 312--GOVERNOR.]

[Illustration: Fig. 313--SECTION OF PILLOW BLOCK.]

Figure 313 represents a section of the pillow block box, crank-pin and
wheel, together with the main journal. It will be seen that the end of
the box next the crank wheel has a circular groove around its outside,
and that a corresponding groove in the crank wheel projects over this
groove. From this latter groove an oil hole of liberal size extends, as
shown, to the surface of the crank-pin. Any oil placed at the upper part
of the groove on the box finds its way by gravity into the groove in
the crank wheel, and is carried by centrifugal force to the outside
surface of the crank-pin; so that whatever other means of lubrication
may be employed, this one will always be positive in its action. This
cut also shows the manner in which the box overlaps the main journal and
forms the oil reservoir.

[Illustration: Fig. 314--CONNECTING ROD. (Page 295.)]

Another feature in the construction of this box is the means by which it
is made to adjust itself in line with the shaft. It will be observed
that it rests on the bottom of the jaws of the frame on two inclined
surfaces, which form equal angles with the axis of the shaft when in its
normal position, and that by moving longitudinally in either direction,
as may be necessary, the box will accommodate itself to a change in the
alignment of the shaft. In order that it may be free to move for this
purpose it is not fitted with the usual fore and aft flanges. By this
means any slight derangement, as in either the outboard or inboard
bearing wearing down the fastest, is taken care of, the movement of the
box on th