IMPROVEMENTS IN COMPOUND MARINE ENGINES
Year: 1883

page_text: LETTERS PATENT to William Bruce Thompson of Dundee in the County of
Forfar, North Britain for an Invention of "IMPROVEMENTS IN COMPOUND
MARINE ENGINES"
PROVISIONAL SPECIFICATION left by the said William. Bruce Thompson
at the Office of the Commissioners of Patents on the 27th November 1883.
WILLIAM BRUCE THOMPSON of Dundee in the County of Forfar, North Britain,
"IMPROVEMENTS IN COMPOUND MARINE ENGINES'
This Invention which relates to Improvements in that class of marine Steam
engines known as "triple compound engines" that is to say, engines in which the
steam is expanded three times, has for its object to enable an equality of potential
or driving power to be applied to both the fore and aft cranks of the Engines of
Steam Ships.
'
The Improvements consist in placing over each of the cylinders which
correspond to the two respective high and low pressure cylinders of an ordinary
compound engine, a high pressure cylinder. These high pressure cylinders may be
of equal or different bores so that the balance of potential or driving power is
capable of being adjusted to exactitude. Both the high pressure cylinders receive
steam direct from the boiler and alternately exhaust the same into the casing of
the second cylinder whence the steam passes to the largest or lowest pressure
cylinder.
.
The Improvements as hereinbefore described apply. to engines in which two
cranks are used, but in applying the said Improvements to three crank engines the
engines are provided with six cylinders, the three upper cylinders being of sizes
which shall produce the necessary balance of potential relatively with that
developed in their corresponding lower cylinders, so that as nearly as possible an
equal driving power acts upon each of the three cranks. The three upper
cylinders are supplied with steam direct from the boiler, which in exhausting from
these, expands into the central lower cylinder and in exhausting from this cylinder
expands into the two low pressure cylinders.
ذ
In lieu of placing the high pressure cylinders above the lower pressure cylinders
of a compound engine as herein before described, they may be placed below the
same, their position being determined according to the general arrangement of the
engines:

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Bruce Thompson in the Patent Office on the 26th May
1884.
WILLIAM BRUCE THOMPSON, of Dundee in the County of Forfar, North Britain
"IMPROVEMENTS IN COMPOUND MARINE ENGINES. ·
My said Invention which relates to Improvements in that class of marine Steam
Engines known as "triple compound engines" that is to say Engines in which the
Steam is expanded three times, has for its object to enable an equality of potential
or driving power to be applied to the fore, and aft, and intermediate cranks of the
Engines of Steam Ships.
t.
The Improvements consist in an Engine in which are six cylinders three of
which are high pressure cylinders and one of which high pressure cylinders is
placed over each of the three cylinders, which collectively correspond to the two
respective high and low pressure cylinders of an ordinary compound Engine.
These high pressure cylinders may be of equal or different bores so that the
balance of potential or driving power is capable of being adjusted to exactitude.
The three upper cylinders are supplied with steam direct from the boiler, which, in
exhausting from these, expands into the central lower cylinder, and in exhausting
from this cylinder expands again into the two low pressure cylinders one at each
side thereof,
In lieu of placing the high pressure cylinders above the lower pressure cylinders
of a compound engine as herein before described, they may be placed below the
same, their position being determined according to the general arrangement of the
engines.
And in order that my said invention may be properly understood, I now
proceed more particularly to set forth the system, mode, or manner in or under
which the same is or may be used or practically carried into effect, reference being
had to the accompanying Drawings and to the letters and Figures marked thereon,
that is to say :-
:-
Figure 1, represents in front elevation a compound marine engine constructed
according to my present Invention.
Figure 2, represents the same in vertical section.
Figures 3, and 4 represent a detached portion of the engine shewing the
arrangement of the valves respectively in vertical and horizontal section. and
hereafter fully described.
In my improved engine the three upper cylinders a, b. and c, are preferably of
such diameter which relatively with the pressure of steam in their respectively
corresponding lower cylinders d, e, and f, shall produce as near as may be a balance
of potential in other words shall transmit equal driving power to each of the
cranks g, h, and . The admission and exhaust valves to and from or between the
several cylinders are so arranged that the three upper cylinders a, b, and c, are
supplied with steam direct from the boiler, which in exhausting from these,
expands into the central lower cylinder e, which corresponds to the high pressure
cylinder of an ordinary compound engine, and in exhausting from this cylinder e,
the steam again expands into the lowest pressure cylinders d, and f, one at each
side respectively of the said central cylinder e. These two last mentioned
cylinders d, and ƒ corresponding to the low pressure cylinders of an ordinary
compound engine.
As regards the arrangement of valves hereinbefore referred to, I prefer to use
such as is shewn at Figures 3, and 4, and which consists of two D-shaped valves j,

page_text: and k, formed separately and turned back to back. These valves, when in this
position, are bolted or otherwise suitably secured together, and they are caused to
operate between the two valve faces l, and m. wherein are two sets of ports through
which the steam passes always with equal and opposite pressures so that the
valves are maintained in equilibrio and high pressure steam can be used without
destroying the faces of the slide valves and ports by the excessive pressure on the
back of the valves only
In connection with the valves j, k, and n, I prefer to employ the spring o, to
counteract the weight of the said valves or to take the said weight off the eccentric
operating such valves.
In lieu of placing the high pressure cylinders above the lower pressure cylinders
of the compound engine hereinbefore described, the said high pressure a, b, and c,
may be placed below the same, their position, under such construction, being
determined according to the otherwise arrangement of the engine.
Having now described and particularly ascertained the nature of my said
Invention and the system mode or manner in or under which the same is or may
be used or practically carried into effect, I would observe in conclusion that
what I consider to be novel and original and therefore claim as the Invention
secured to me by the herein before in part recited Letters Patent is :-
The triple compound marine engine constructed with the three high pressure
cylinders a, b, and c, of equal or different bores and wherein the steam is
admitted to and expands from the said three cylinders through the equilibrium
slide valves j, and k, into the central cylinder e, from which the steam again
expands into the two lowest pressure cylinders d, and f, all essentially as and for
the purposes hereinbefore set forth with reference to the accompanying Drawings.
In Witness Whereof I the said William Bruce Thompson have hereunto set my
hand and Seal this fourteenth day of May in the year of our Lord One thousand
eight hundred and eighty four.
WILLIAM BRUCE THOMPSON (L.B.)