IMPROVE- MENTS IN MARINE ENGINES
Year: 1874

page_text: LETTERS PATENT to Daniel Rankin, of Greenock, in the County of
Renfrew, North Britain, Engineer, for the Invention of "IMPROVE-
MENTS IN MARINE ENGINES,"
Sealed the 2nd April 1875, and dated the 5th October 1874.
PROVISIONAL SPECIFICATION left by the said Daniel Rankin at the
Office of the Commissioners of Patents, with his Petition, on the
5th October 1874.
I, DANIEL RANKIN, of Greenock, in the County of Renfrew, North
Britain, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN MARINE ENGINES," to be as follows, that is to say :-
This Invention has for its object to render available in a certain class
of paddle steamer the advantages obtainable with marine engines having
only two cylinders but arranged to work under ordinary circumstances
on what is known as the compound or high and low pressure system.
Paddle steamers of the class referred to are required to have the two
paddle wheels capable of being disconnected, and heretofore four

page_text: cylinders have been considered necessary for allowing that to be done
when compound engines have been employed, because it is necessary in
ordinary working for each high-pressure cylinder to operate in perfect
concert with the low-pressure cylinder to which its steam passes, which
does occur when the parts of the paddle shaft to which the cylinders are
separately connected are disconnected from each other.
By the present Invention the two cylinders working ordinarily the
one as "high pressure" and the other as "low pressure" are arranged
in an improved manner, so that when it is required to disconnect the
two parts of the paddle shaft each cylinder can be worked quito inde-
pendently of the other. A valve is provided for stopping the connecting
passage between the exhaust port of the high-pressure cylinder and the
valve casing of the low-pressure cylinder, and a separate passage and
valve are provided to lead the exhaust steam from the high-pressure
cylinder directly to the condenser or to the atmosphere.
When the cylinders are disconnected from each other the low-pressure
one is worked by steam which is admitted to it by a special branch pipe
and through what is known as a reducing valve, so that it may be of a
pressure sufficiently below the full boiler pressure to be suitable for
working the low-pressure cylinders.
The Invention is equally applicable to engines for driving twin screw
propellers, or to any marine engines in which it may at times be
required to disconnect the crank or shaft acted on by one cylinder from
that acted on by the other cylinder.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Daniel Rankin in the Great Seal Patent Office on
the 5th April 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DANIEL
RANKIN, of Greenock, in the County of Renfrew, North Britain,
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent bearing date the Fifth day of October, in the year of our
Lord One thousand eight hundred and seventy-four, in the thirty-

page_text: eighth year of Her reign, did, for Herself, Her heirs, and successors,
give and grant unto me, the said Daniel Rankin, Her special licence
that I, the said Daniel Rankin, my executors, administrators, and
assigns, or such others as I, the said Daniel Rankin, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
MARINE ENGINES," upon the condition (amongst others) that I, the said
Daniel Rankin, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should par-
ticularly describe and ascertain the nature of the said Invention, and
in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Daniel Rankin, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement in writing, reference being had to the accom-
panying Drawings, that is to say:-
My said Invention has for its object to render available in certain
classes of paddle and screw steamers the advantages obtainable with
marine engines having only two cylinders but arranged to work under
ordinary circumstances on what is known as the compound or high and
low pressure system.
In one of the classes of steamers referred to it is requisite that the
two paddle wheels shall be capable of being disconnected from each
other, and heretofore four cylinders have been considered necessary for
allowing that to be done when compound engines have been employed,
because it is necessary in the ordinary working of such engines for each
high-pressure cylinder to operate in perfect concert with the low-pressure
cylinder to which its steam passes, which co-operation does not occur
when the parts of the paddle shaft to which the cylinders are separately
connected are disconnected from each other.
In another of the classes of steamers referred to twin screws are used,
which whilst ordinarily working in concert are sometimes required to

page_text: operate at different speeds or in different directions for turning or
steering the steamer, and as in the case of the paddle steamers four
cylinders have hitherto been considered nccessary when compound
engines have been employed in such steamers.
"
By my present Invention the two cylinders working ordinarily the one
as high pressure" and the other as "low pressure are arranged in an
improved manner, so that when it is required to disconnect the two parts
of the paddle shaft in the one case, or to drive the two shafts of the twin
screws differently from each other in the other case, each cylinder can
be worked quite independently of the other. I provide a valve for
stopping the connecting passage between the exhaust port of the high-
pressure cylinder and the valve casing of the low-pressure cylinder; or
according to a preferable modification I simply provide a valve or valves
to lead the exhaust steam from the high-pressure cylinder directly to
the condenser or to the atmosphere, or both, such valve or valves being
loaded to a higher pressure than that employed in the low-pressure
cylinder.
When the cylinders are disconnected from each other the low-pressure
one is worked by steam, which is admitted to it by a special branch
pipe, and through what is known as a reducing valve, so that it may be
of a pressure sufficiently below the full boiler pressure to be suitable for
working the low-pressure cylinder.
And in order that my said Invention and the manner of performing
the same may be properly understood I hereunto append a Sheet of
explanatory Drawings, to be herein-after referred to, and representing
portions of marine engines as fitted with my improved arrangements.
In these Drawings the same reference numerals are used to mark the
same or like parts wherever they are repeated.
Figure 1 of the Drawing is a plan and Figure 2 is a side elevation of
the cylinders of a pair of paddle engines as constructed, and proportioned
for being ordinarily worked together on the compound system, but also
fitted with the parts necessary for carrying out my Invention. The
steam pipe 1 communicates as usual with the valve casing 2 of the high-
pressure cylinder 3, and it has in addition a branch pipe 4 leading to a
reducing valve apparatus 5, which so far as represented is of a kind well
known as Auld's, but which may be of any other suitable known kind;
from the reducing valve 5 a pipe 6 leads the steam of reduced pressure

page_text: to the passage or space 7 leading from the exhaust port of the high-
pressure cylinder 3 to the valve casing 8 of the low-pressure cylinder 9;
the space or casing 7 between the two cylinders 3, 9, has fitted to it a
valve casing 10 and escape pipe 11 with a valve, indicated by dotted
lines in Figure 2, and loaded to about fourteen pounds per square inch,
and allowing any steam above that pressure to escape to the atmosphere;
there is also fitted to the same casing 7 a valve casing 12 with a valve
loaded to twenty pounds per square inch and opening to the condenser,
being connected by a branch pipe 13 to the exhaust pipe 14 of the low-
pressure cylinder 9. The reducing valve 5 is also used as a throttle or
stop valve for the low-pressure cylinder 9, and may be kept closed when
the two paddles are operating in unison, but when it is necessary to
disconnect the respective parts of the shaft appertaining to the two
paddles then steam is allowed to pass through the reducing valve 5 from
the pipe 4 to the valve casing 8 of the low-pressure cylinder. The
reducing valve 5 is proportioned and loaded to suit the pressure of the
steam intended to be employed, and by preference in such a way that
the powers developed by the two cylinders will be about equal.
screws.
Figure 3 is a horizontal section and Figure 4 an elevation of a pair of
inverted cylinder compound engines for driving the shafts 15, 16, of twin
In this case the cylinders 3, 9, are quite detached from each
other, and a casing 7 formed round the high-pressure cylinder 3 receives
the exhaust steam from that cylinder, and from it the steam passes to
the low-pressure valve casing 8 by the pipe 17. In this modification
a valve (12), corresponding to that herein-before described with reference
to Figures 1 and 2, as leading from the space 7 to the condenser, is not
shown, and either class of engines may be made without such valve.
In other respects the application of the valves in connection with the
space 7 is substantially the same in both cases, as is made easily apparent
by the use of the same reference numerals for marking the corresponding
parts in both.
Having thus particularly described my said Invention, and the
manner of performing the same, I have to state that I do not restrict
myself to the precise details herein described and delineated, and that I
do not claim the application of reducing valves to compound steam
engines excepting in the manner and for the special purposes herein
described and defined; what I believe to be novel and original and
claim as the Invention secured to me by the herein-before in part recited

page_text: :
Letters Patent being the arranging of a pair of marine engine cylinders
consisting of one high-pressure cylinder and one low-pressure cylinder,
so as to drive two paddle or screw shafts which ordinarily work in
concert, but arc also capable of operating in a disconnected manner when
required, provision being made for passing steam directly from the
boiler through a reducing valve to the low-pressure cylinder when the
shafts are disconnected, all substantially as herein-before described.
In witness whereof, I, the said Daniel Rankin, have hereunto
set my hand and seal, this Third day of April, in the year of
our Lord One thousand eight hundred and seventy-five.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
DANIEL RANKIN.
(L.S.)