IMPROVEMENTS IN DISCONNECTIVE COMPOUND. STEAM ENGINES
Year: 1885

page_text: FFF
We, JOHN FINLAY RANKIN, and MATTHEW RANKIN, of the Eagle Foundry,
Greenock, in the County of Renfrew, North Britain, Engineers, do hereby declare
the nature of our said invention for "IMPROVEMENTS IN DISCONNECTIVE COMPOUND.
STEAM ENGINES" and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement, that is to say :—
Our said Invention relates to compound steam engines having four or more
cylinders, and working with three or four stages of expansion, and our object is tó
arrange the cylinders and other parts, and especially connecting pipes or passages
and their valves, in an improved manner, and so that when any cylinder is in any
way disabled, or requires to be examined or repaired, it and the cylinder tandem to
it, can be disconnected from the other cylinders, and the engines can be kept
working with the other cylinders. The power of thus working part of the engines
when another part is disabled will be of great practical value; and in the case of
screw or paddle steamers for which the improvements are mainly designed, such
power may in many cases be the means of saving the ship. The improvements are
also applicable to land engines as well as to marine engines.
Our Invention is applicable to various general arrangements of engines, certain
parts having simply to be repeated when the number of cylinders is increased by
using two or three cylinders instead of one for any one of the stages of expansion.
The improvements will be most readily explained with the aid of explanatory
drawings, of which four sheets are hereunto appended, and in which the same
reference letters are used to mark the same or like parts wherever they are
repeated. The engines shown as examples in the accompanying drawings are all
inverted-cylinder screw-propeller engines; but the application of our improve-
ments to other compound engines will be effected without difficulty in a similar
manner.
Figures, 1, and 2, on sheet, 1, are a plan and side elevation of engines arranged
for three stages of expansion. These engines comprise two small high-pressure
cylinders A1, A2, one being placed above and tandem with the second-stage or
intermediate cylinder, B, and the other above and tandem with the third-stage or
low-pressure cylinder, C. The steam from the boiler reaches the engines by a
pipe, S, having branches with stop valves, E, F, connected to the valve casings of

page_text: the two high-pressure cylinders, A1, A2. The exhaust from one cylinder, A 2,
passes (when all the cylinders are working) through a pipe, G, connecting with a
pipe, H, which leads the exhaust from the other cylinder, A 1, down to the valve
casing of the intermediate cylinder, B; and the exhaust from this cylinder, B,
passes ordinarily by the pipe, I, to the valve casing of the low-pressure cylinder, C,
the exhaust from which passes by the pipe, to the condenser, K. An additional
pipe, L, having on it a spring-loaded or other reducing valve, M, is provided for
leading the exhaust of one high-pressure cylinder, A 2, directly to the cylinder, C,
below it; and another pipe, N, having a stop valve, O, is also provided for leading
the exhaust from the intermediate cylinder, B, directly to the condenser or to the
atmosphere. The piston rods of the cylinders, A1, and B, are connected to one
crank, and those of the cylinders, A 2, and C, to another crank. If it becomes
desirable to disconnect the cylinders A 1, and B, the supply of high-pressure steam
to the cylinder, A 1, is stopped by closing the valve, E; and the steam exhausting
from the other high pressure cylinder, A 2, then passes through the spring-loaded
or other reducing valve M, and pipe, L, direct to the low-pressure cylinder, C. If
on the other hand the cylinders, A 2, and C, have to be disconnected then the steam
is shut off from the cylinder, A2, by closing the valve, F, and acts only in the
cylinders A 1, and B, passing from the latter through the valve, O, and pipe, N,
directly to the condenser or to the atmosphere.
In the example shown on sheet, 2, figures, 3, and 4, being respectively a plan and
a side elevation, the four cylinders, A, B, C, D; are proportioned and arranged for
four stages of expansion. The steam pipe, S, communicating through the stop
valve, E, with the valve casing of the high-pressure cylinder, A, also communicates
through a reducing valve, M, and pipe, L, with the valve casing of the third-stage
cylinder, C, and the other connecting pipes and valves are substantially the same
as in the first example, there being added a pipe, Q, to connect the exhaust port of
the third-stage cylinder, C, with the valve casing of the fourth-stage or low-
pressure cylinder, D, the exhaust of which is led by the pipe, J, to the con-
denser, K. In this example there are two cranks, and either the two cylinders, A, B,
can be worked by themselves, or the two cylinders, C, D, the stop valve, O, being
opened in the one case and the stop valve, E, closed in the other case, steam being
admitted to the cylinders, C, and D, by means of the reducing valve, M.
In the example shown in plan in figure, 5, and in side elevation in figure, 6, on
sheet, 3, there are five cylinders working with four stages of expansion. This
example is the same as the first one with a fifth cylinder and a third crank added
to it, and the connecting pipes and valves are the same as far as disconnecting is
concerned; but the fifth cylinder, D, has always to work with the two cylinders, A 2,
and C, whilst these three cylinders can work alone, or the other two cylinders can
work alone.
In the example shown on sheet, 4, figure, 7, being a plan and figure, 8, a side
elevation, there are six cylinders working with four stages of expansion. Three
high-pressure cylinders, A 1, A2, A3, are placed respectively over the second-stage
cylinder, B, the third-stage cylinder, C, and the fourth-stage or low-pressure
cylinder, D, the three piston rods being connected to three cranks. The arrange-
ment is like the first example with the cylinders, A. 3, and D, added to it and with
the corresponding additional stop valves and pipes, F 2, M 2, G2, L2. In this
arrangement any two cylinders connected with one crank or any four cylinders
connected with two cranks can be worked without working the remaining
cylinders.
The arrangements of the cylinders in relation to each other as hereinbefore
described are not only suitable for the convenient application of the valves and
pipes as described for disconnecting purposes but are also we believe the best for
satisfactorily utilising the power of the steam, and in the case of the four-stage or
quadruple-expansion engines have never been before adopted or proposed so far as
we are aware.

page_text: Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed, we declare that what
we claim is
1. The application to triple-expansion and quadruple expansion steam engines of
stop valves, reducing valves, and connecting pipes arranged as hereinbefore described
to allow of the disconnection of some of the cylinders substantially in the manner
herein before described.
2. The arranging of the cylinders of quadruple-expansion engines in relation to
each other in any of the modes hereinbefore described.
EDMUND HUNT,
Applicants' Agent.