IMPROVEMENTS IN COMPOUND MARINE STEAM ENGINES
Year: 1882

page_text: LETTERS PATENT to James McFarlane, of Dundee, in the County of Forfar,
North Britain, Engineer for an Invention of “IMPROVEMENTS IN COMPOUND
MARINE STEAM ENGINES
"
PROVISIONAL SPECIFICATION left by the said James MoFarlano at the
Office of the Commissioners of Patents on the 6th November 1882.
JAMES MºFARLANE, of Dundee, in the County of Forfar, North Britain, Engineer,
"IMPROVEMENTS IN COMPOUND MARINE STEAM ENGINES
»
This Invention relates to compound marine steam engines designed for working
with steam of high initial pressure and with three stages of expansion, and the
object of it is to combine three cylinders with two cranks in an improved manner
and so as to obtain a better equalisation of the strains upon the two cranks
together with other practical advantages.
In carrying out the Invention according to one modification in which inverted
cylinders are used for driving the scrow propeller, the low-pressure cylinder is
placed above one crank and the intermediate cylinder above the other crank and
the high-pressure cylinder is placed in line with and either above or below, but by
preference above the low-pressure cylinder, instead of being in line with the
intermediate cylinder as in some arrangements. With the improved arrangement
the intermediate cylinder is made comparatively larger than heretofore, and a
better control and adjustment of the action of the steam in the several cylinders
is secured, a separate expansion valve being by preference used with the inter-
mediate cylinder or other means being adopted admitting of the cut-off in that
cylinder being adjusted independently. The low-pressure cylinder is made com-
paratively smaller and a correspondingly smaller capacity of air pump and.
circulating pumps and reduced condenser surface are required.
In other modifications of the improved engines the cylinders may be arranged
horizontally or diagonally for driving a single screw or for driving twin screws
or for driving paddle wheels; but in all cases the high-pressure and low-pressure
cylinders act through ono connecting rod whilst the intermediate cylinder acts
through another connecting rod.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James McFarlane in the Great Seal Patent Office on the 3rd May
1883.
JAMES MCFARLANE, of Dundee,, in the County of Forfar, North Britain,
Engineer, IMPROVEMENTS IN COMPOUND MARINE STEAM ENGINES
"
My said Invention relates to compound marine steam engines designed for
working with steam of high initial pressure and with three stages of expansion,
and the object of it is to combine three cylinders with two cranks in an improved
manner, and so as to obtain a better equalisation of the strains upon the two
cranks, together with other practical advantages.
In carrying out my Invention, according to some modifications in which inverted
cylinders are used for driving the screw propeller, the low-pressure cylinder is
placed above one crank and the intermediate cylinder above the other crank, and
the high-pressure cylinder is placed in line with and either above or below, but by
preference above the low-pressure cylinder, instead of being in line with the
intermediate cylinder as in some arrangements. With my improved arrangement
the intermediate cylinder is made comparatively larger than heretofore, and a
better control and adjustment of the action of the steam in the several cylinders
is secured, a separate expansion valve being by preference used with the inter-
mediate cylinder, or other means being adopted admitting of the cut-off in that
cylinder being adjusted independently. The low-pressure cylinder is made
comparatively smaller, and a correspondingly smaller capacity of air pump and
circulating pumps and reduced condenser surface are required.
In other modifications of my improved engines the cylinders may be arranged
diagonally or horizontally, for driving a single scrow, or for driving twin screws,
or for driving paddle wheels; but in all cases the high-pressure and low-pressure
cylinders act through one connecting rod whilst the intermediate cylinder acts
through another connecting rod.
And in order that ny said Invention and the manner of performing the same
may be properly understood I hereunto append two sheets of explanatory drawings
to be hereinafter referred to and representing several examples of my improved
marine engines.
Figures 1, 2, 3, on sheet 1 of the accompanying drawings represent in plan,
in side elevation, and in end elevation a set of inverted-cylinder screw-propeller
engines. Figures 4, 5, and 6 are similar views of a second modification. Figures
7, and 8, on sheet 2 are a plan and an end elevation of an arrangement of the
engines for driving twin screws. Figures 9 and 10 are a plan and a side elevation
of a modification in which the cylinders are arranged diagonally or in an inclined
position for driving paddle wheels; and figures 11 and 12 are a plan and an
elevation of a modification in which the cylinders are arranged horizontally. In
these drawings the same reference numerals are used to mark the same or like
parts wherever they are repeated. The general features only of the several
arrangements are shown, and it is to be understood that any parts or details
which are not delineated or described are to be constructed or fitted as in existing
engines or in an analogous manner.
In the modification shown in figures 1, 2, and 3, there are three inverted
cylinders 21, 22, 23, the piston rods of which are connected to two cranks on the
shaft, 24. The high-pressure cylinder, 21, into which the steam is first admitted
is placed in line with and above the low-pressure cylinder, 23; the two pistons
being on the same rod which is connected to one of the cranks. After working in

page_text: the high-pressure cylinder, 21, the steam passes by a pipo, 25, to the valve casing
of the intermediato cylinder, 22, which cylinder is placed over, and has its piston
rod connected to the other crank. From the intermediate cylinder, 22, the steam
exhausts into a casing partly surrounding it and which communicates with the
valve casing of the low-pressure cylinder 23. In this way the steam is expanded
through three separate stages; and the cylinders can be proportioned to give very
satisfactory results as regards the distribution of the strains, the action in the
cylinders being easily controlled by means of a separately adjustable cut-off valve
(of which the rod, 26, is shown in figure, 2, the rod 27, being that of the ordinary
slide valve on the back of which the cut-off valve works) such cut-off valve being
applied to the intermediate cylinder, 22. The air pump 28, and circulating
pump, 29, are represented as placed in a position for being worked by means of a
lover from the piston rod of the high-pressure and low-pressure cylinders, 21, 23.
The modification shown in figures, 4, 5, and 6, differs from that shown in
figures 1, 2, and 3, merely in having the high-pressure cylinder, 21, placed below
the low-pressure or third cylinder, 23. The steam passes from the high-pressure
cylinder, 21, into a casing partly surrounding the intermediate or second
cylinder, 22, and communicating with its valve casing, and from this second
cylinder it passes by an inclined pipe, 30, to the low-pressure cylindor 23.
In the arrangement shown in figures, 7, and 8, there is provided for driving cach
screw shaft, 24, a set of three cylinders 21, 22, 23, combined as shown in figures, 1,
2, and 3. A single surface condenser, 32, of adequate size is made to serve for
both sets of engines and the lower parts of the framings are combined; but in
other respects each set of engines is complete in itself with all requisite
accessories. If preferred the high-pressure cylinders, 21, may be placed below tho
low-pressure cylinders, 23, as in the modification shown in figures 4, 5, and 6.
In the modification of diagonal or inclined engines shown in figures, 9, and 10,
and in that of horizontal engines shown in figures 11 and 12 the three
cylinders, 21, 22, 23, are arranged relatively to the crank shaft, 24, substantially as
in the modification shown in figures 1, 2 and 3; thoy may however, if preferred,
be arranged as in the modification shown in figures, 4, 5, and 6. In each of the
Inodifications (figures 9, 10 and figures 11, 12) the condenser and pump details
are arranged as is usual with diagonal and horizontal engines respectively.
Having thus particularly described my said Invention and the manner of
performing the same I have to stato that I do not restrict myself to the precise
details herein described or delineated but that what I believe to be novel and
original and claim as the Invention secured to me by and in terms of the horein-
before in part recited Letters Patent is :-
1. The constructing of compound marine steam engines working with three
stages of expansion with a high pressure or first cylinder and a low pressure or
third cylinder connected to one crank, and with an intermediate or second
cylinder connected to another crank substantially as bereinbefore described.
2. In compound marine steam engines working with three stages of expansion
the providing of the intermediate or second cylinder with a cut-off valve or
equivalent means for independently adjusting the cut-off of that cylinder
substantially as and for the purposes hereinbefore described.
hand
In Witness whereof, I, the said James McFarlane, have hereunto set my
and scal this first day of May in the year of our Lord One thousand
oight hundred and eighty-three.
JAMES MOFARLANE (L.S.)