The heavy case iron base is cast in two sections, the rear part being
securely bolted to the front section. To the front section is also
bolted the main engine frame. This frame contains the bar guides for
the cross-head, and pillow block bearing for the double disc crank
shaft, and also forms the front head for the low pressure cylinder,
which is securely bolted to it.
The high pressure cylinder is attached to the low pressure cylinder by
two brackets securely bolted, and is supported by a pedestal, bolted
to the rear part of base. By this arrangement, both the high and low
pressure pistons are upon the same piston rod, which necessitates of
but one cross-head, connecting rod and crank.
The valve of the high pressure cylinder is operated and completely
under the control of the automatic shaft governor attached to one of
the band wheels, while the valve of the low pressure cylinder receives
its motion from a single eccentric on crank shaft at opposite side of
engine.
When engine is running, the steam enters the high pressure cylinder
first, and after performing its work there, exhausts through the
receiver pipe into the low pressure cylinder, and there exerts its
minimum force by expansion, and passes out to the condenser, if used,
or exhausts into the open air.