Improvements in Marine Steam Engines.
Year: 1891

page_text: Date of Application, 12th May, 1891
Complete Specification Left, 11th Feb., 1892-Accepted, 12th Mar., 1892
PROVISIONAL SPECIFICATION.
Improvements in Marine Steam Engines.
We, WALTER BROCK, of the firm of Denny & Company of Dumbarton in the
County of Dumbarton, North Britain, Engineer, and JAMES WEIR, of Holm
Foundry, Cathcart, in the County of Renfrew, North Britain, Engineer, do
hereby declare the nature of this invention to he as follows, that is to say :-
Our invention relates to marine steam engines of a kind ordinarily working with
two or more than two stages of expansion, and our object is to obtain greater
relative efficiency and economy of fuel, when such engines are worked at considerably
below their full power, than is possible with existing arrangements of such engines.
War steamers have frequently to be propelled for considerable periods at half or
other portion of their maximum speed but with triple-expansion engines (for
example) the relative sizes of the several cylinders, and the distribution and cut-off
valve arrangements have to be such as will secure the best results when working at
full power but which will not give proportionately satisfactory or economical
results when working at lower powers. For the lower powers, either the pressure
must be reduced, or the steam must be cut off earlier in the stroke from the high-
pressure or first-stage cylinder; and in the first case the full proportionate duty
which should be obtainable from the maximum pressure the boilers are capable of
supplying is not got, whilst in the second case the strains in the high pressure or
first-stage cylinder are rendered more severe and irregular and vary to a greater
extent, and the action in the second-stage and third-stage cylinders becomes defective
owing to the greater expansion of the steam in the first-stage cylinder.
In carrying out our invention according to one modification we provide an
additional cylinder which may be arranged tandem to the (ordinarily) first-stage
cylinder, and we also provide connecting pipes or passages with stop valves to
allow of the working to be modified to suit the varied requirements at different
times. When working full power the added cylinder may be made inoperative, or
it and the cylinder with which it is combined may together be worked as one
ordinary first-stage cylinder. The added cylinder is smaller than the (ordinary
first-stage) cylinder; and when the engines have to work at, for example, a fourth
of the full power, the initial steam is shut off from the (ordinarily) first-stage
cylinder, being admitted only to the added cylinder. In the added cylinder the
steam is cut off at a suitable point for the power required and exhausts from that
cylinder to the valve casing of the (ordinarily) first-stage cylinder. The engines thus
become quadruple expansion engines, the three ordinary cylinders working exactly
as if supplied with steam of reduced pressure directly from the boiler, whilst the
duty due to the higher pressure is realised by means of the added cylinder.
Instead of the added cylinder being arranged as described it may be combined
with the other parts of the engines in any other convenient way.
Dated this Eleventh day of May 1891.

page_text: COMPLETE SPECIFICATION.
Improvements in Marine Steam Engines.
We, WALTER BROCK, of the firm of Denny and Company, of Dumbarton in
the County of Dumbarton, North Britain, Engineer and JAMES WEIR, of Holm
Foundry, Cathcart, in the County of Renfrew, North Britain, Engineer do hereby
declare the nature of this invention 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 marine steam engines of- kinds ordinarily working
with two or more stages of expansion, and our object is to obtain greater relative
efficiency and economy of fuel, when such engines are worked at considerably below
their full power, than is possible with existing arrangements of such engines. War
steamers have frequently to be propelled for considerable periods at half or other
portion of their maximum speed, but with triple expansion engines (for example)
the relative sizes of the several cylinders and the distribution and cut-off valve
arrangements have to be such as will secure the best results when working at full
power, but which will not give proportionately satisfactory or economical results,
when working at low powers. For the lower powers, either the pressure must be
reduced, or the steam must be cut off earlier in the stroke from the high-pressure
or first-stage cylinder; and in the first case the full proportionate duty which should
be obtainable from the maximum pressure the boilers are capable of supplying is
not got; whilst in the second case the strains in the high-pressure or first-stage
cylinder are rendered more severe and irregular and vary to a greater extent;
and the action in the second-stage and third-stage cylinders becomes defective
owing to the greater expansion of the steam in the first-stage cylinder.
In carrying out our invention we provide an additional cylinder which is smaller
than the (ordinarily) first-stage cylinder, and we also provide connecting pipes or
passages with valves arranged in a manner to allow the working to be modified to
suit the varied requirements at different times. When working full power the
added cylinder may be made inoperative, or it and the cylinder with which it is
combined may together be worked as one ordinary first-stage cylinder. When the
engines have to be worked at, for example, a fourth of the full power, the initial
steam is shut off from the (ordinarily) first-stage cylinder, and is admitted only to
the added cylinder. In the added cylinder the steam is cut off at a suitable point
for the power required, and exhausts from that cylinder to the valve casing of the
(ordinarily) first-stage cylinder. The engines thus (if ordinarily triple-expansion
engines) become quadruple-expansion engines, the three ordinary cylinders working
exactly as if supplied with steam of reduced pressure directly from the boilers,
whilst the duty and economy due to the higher pressure are realised by means of
the added cylinder.
Our improvements are applicable to various arrangements of marine engines, and
on seven accompanying shects of explanatory drawings we show some applications
as examples, from which our invention and the manner of performing the same may
be properly understood.
On each sheet of the accompanying drawings a single example is shown; but in
every case only as much of the engine is shown as is considered necessary in
explaining the improvements; and it is to be understood that parts not described
or delineated are to be constructed or arranged in any suitable known manner.
All the engines shown are inverted-cylinder screw-propeller engines.
On Sheet, 1, Figures, 1, 2 and 3, are a sectional plan, a sectional side elevation,
and a transverse vertical section, of Example No. 1.
On Sheet, 2, Figures 4, 5, and 6, are a sectional plan, a sectional side elevation,
and a sectional end elevation of Example No. 2,

page_text: 1, 0, 0, are a seccionar pran, a sectional side elevation, ana
a transverse vertical section, of Example No. 3.
On Sheet, 4, Figures 10, 11, and 12, are a sectional plan, a sectional side elevation,
and a transverse vertical section, of Example No. 4.
On Sheet, 5, Figures, 13, 14, and 15, are a plan, a side elevation, and a transverse
vertical section, of Example No. 5.
On Sheet, 6, Figures, 16, and 17, are a plan and a side clevation, of Example
No. 6.
On Sheet, 7, Figures, 18, 19, and 20, are a plan, a sectional side elevation, and a
transverse vertical section, of Example No. 7.
In these drawings the same reference letters and numerals, are used to mark the
same or like parts wherever they are repeated. In every example the letter, C,
marks the added cylinder, the (ordinarily) high-pressure or first-stage and other
cylinders being distinguished respectively by the references, C1, C2, and C 3.
Example, 1, Sheet, 1, comprises an existing triple-expansion engine, having
cylinders. C1, C2, C3, arranged for operating on three cranks, the added
cylinder, C, being placed tandem with the first-stage cylinder, C1. The piston
rod, R, and valve rod, R 1, for the added cylinder, C, are provided with
couplings, A, B, which can be disconnected when that cylinder is to be inoperative.
The steam pipe, S. communicates with a valve box, D, having in it a valve, E,
which when open admits steam by a passage, S 1, into the (ordinarily) first-stage
valve casing, V1; whilst a second valve, F, when open allows steam from the valve
box, D, to pass by a pipe, F 1, to the valve casing, V, of the added cylinder, C.
The exhaust from the added cylinder, C, takes place through a pipe, G 1, and
valve, G, into the passage, S1, leading into the valve casing, V 1.
Example, 2, Sheet, 2, is like Figure, 1, excepting that the added cylinder, C, is
placed above the low-pressure or (ordinarily) third-stage cylinder, C 3.
In Examples, 1, and, 2, the added cylinder, C, can be entirely disconnected and
removed in the event of injury from shot, or as a precaution before action.
In Example, 3, Sheet, 3, the added cylinder, C, and the (ordinarily) first-stage
cylinder, C1, are proportioned for working together with high-pressure steam,
when extra power is required. In this example the valves by the opening or
closing of which the engine is made to work as a triple-expansion engine with full
power, or as a quadruple-expansion engine working with smaller power, are arranged
in immediate connection with the high-pressure valve casing, V 1. The steam
enters at, S, Figure, 9, into a chamber whence it has access through a valve, E,
to the distribution valves, V 1, of the cylinder, C 1, and through a valve, F, and
pipe, F1, to the valves, V, of the added cylinder, C. The steam from the added
cylinder, C, passes by a pipe, G 1, into a chamber having in it valves, G, and, G2,
communicating respectively with the steam and exhaust sides of the valves, V 1.
When working with extra power the valves, E, F, and, G2, are open and the
valve, G, is closed. When working with ordinary full power, that is without the
added cylinder, C, the valve, F, is closed; and when working with reduced power
or as a quadruple-expansion engine, the valves, E, and, G2, are closed, and the
valves, F, and, G, opened. The spaces, H, HI, communicate with the valve casing
of the (ordinarily) second-stage cylinder, C 2.
Example, 4, Sheet, 4, is like Example, 3, excepting that the added cylinder, C,
is placed above the (ordinarily) second-stage cylinder, C 2.
In Example, 5, Sheet, 5, the added cylinder, C, is placed on the same level as the
other cylinders, and has an additional crank in connection with it. For a low
power the whole works as a quadruple-expansion engine; but passages and valves
are provided in connection with the cylinders, C, and, C1, to allow of these
cylinders being worked as high-pressure cylinders and so render the whole a triple-
expansion engine for full power. Or either the added cylinder, C, or the low-
pressure cylinder, C 3, may be disconnected and the three remaining cylinders be
worked as a triple-expansion engine. Figure, 15, is a section showing the valves, V,

page_text: of the added cylinder, C, and also the stop valves E, F, G, G2, which correspond
to the similarly marked valves of the other examples.
Example, 6, Sheet, 6, comprises two cylinders, C1, C2, as in an ordinary two-
stage (commonly termed "compound") engine, with a cylinder, C, added for
working as a whole with triple expansion for a low power. In connection with the
cylinders, C, and C1, passages and valves (E, F, G, G 2,) are provided exactly as
for the corresponding cylinders of Example, 5.
Example, Sheet, 7, is constructed like Example, 6, for working either as
"compound with two stages of expansion, or as a triple-expansion engine; but
the cylinders are arranged for two cranks instead of three, the added cylinder, C,
being placed above the second-stage or low-pressure cylinder, C2. Figure, 20,
shows the valves, V 1, for the (ordinarily) high-pressure or first-stage cylinder, C 1,
and also passages and valves for determining the route to be taken by the steam.
In addition to valves, E, F, G, G 2, for the same purposes as the corresponding
valves in examples hereinbefore described, there are, in Example, 7, valves, J, K,
with appropriate pipes or passages,-one, J, (Figure 18) for admitting steam
exhausted from the cylinder, C1, to the added cylinder, C, and the other, K, for
admitting steam exhausted from the added cylinder, C, directly into the exhaust
passage of the low-pressure cylinder, C 2. With this arrangement of valves and
passages the engine may be, worked with three or two stages of expansion; and for
two-stage or compound" working the added cylinder, C, may be made inoperative,
or it may be made to work either with the high pressure cylinder, C1, or with the
second-stage or low-pressure cylinder, C 2.
<
For the valves and other parts hereinbefore described or shown in the drawings
any suitable known equivalents may be substituted; and any arrangement of valves
and passages described as part of any example may be applied to or adapted to any
other example if desired.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
In marine steam engines constructed for working with two or more stages of
expansion adding, in each case, an extra cylinder with appropriate passages and
valves arranged to allow of working with an extra stage of expansion when a
lower than the maximum power is to be developed, and otherwise combining
and arranging the parts of an engine substantially as and for the purposes
herein before described.
Dated this Tonth dow of Wah……………………… 1005
EDMUND HUNT,
Applicants' Agent.