IMPROVEMENTS IN MARINE STEAM ENGINES
Year: 1872

page_text: LETTERS PATENT to Frederick Carley Coxhead, of 11, Low Hill,
Liverpool, in the County of Lancaster, and James John Miller, of
17, Albert Terrace, New Church Road, Camberwell, in the County
of Surrey, for the Invention of 'IMPROVEMENTS IN MARINE STEAM
ENGINES."
66
Sealed the 24th January 1873, and dated the 27th July 1872.
PROVISIONAL SPECIFICATION left by the said Frederick Carley..
Coxhead and James John Miller at the Office of the Commissioners
of Patents, with their Petition, on the 27th July 1872.
We, FREDERICK CARLEY COXHEAD, of 11, Low Hill, Liverpool, in the
County of Lancaster, and JAMES JOHN MILLER, of 17, Albert Terrace,
New Church Road, Camberwell, in the County of Surrey, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN MARINE
STEAM ENGINES," to be as follows :—

page_text: low-pressure cylinder, as is the case in the engines known as compound
engines, there is difficulty in controlling the engines when from the
pitching of the vessel the screw is lifted out of the water and so the
engines are relieved from their load. By means of a governor, or even
by the stop valve, the entry of fresh steam into the cylinder may be
prevented, but nevertheless the high vacuum in the condenser and the
steam and moisture already in the cylinder and passages is sufficient to
cause the engines to make several rotations, and a dangerous velocity
may even be attained. To prevent this we employ a large valve, by
which air may be admitted to the condenser so as instantly to destroy.
the vacuum when necessary, and in order that this valve, which requires
considerable power to control it, may be operated with sufficient rapidity
we connect with it a steam cylinder.
Or an
We prefer to apply the steam pressure to hold the valve in its scat
against the pressure of the atmosphere, so that when the governor by
opening a valve removes the steam pressure air at once enters the con-
denser, or steam may be applied in other ways to control the valve
opening into the condenser. Or in place of steam air or water may be
employed so as to insure the rapid action of a large valve.
equilibrium valve may be employed, and then the pressure of the air in
one direction being balanced more or less completely by the pressure in
the opposite direction a large area for the admission of air can be opened
by the direct action of the governor, or of the hand lever which works
the stop valve.
SPECIFICATION in pursuance of the conditions of the Letters Patent, 2
filed by the said Frederick Carley Coxhead and James John Miller
in the Great Seal Patent Office on the 27th January 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, FREDERICK
CARLEY COXHEAD, of 11, Low Hill Liverpool, in the County of Lancaster,
and JAMES JOHN MILLER, of 17, Albert Terrace, New Church Road,
Camberwell, in the County of Surrey, send greeting.
3
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-seventh day of July, in the
year of our Lord One thousand eight hundred and seventy-two, in tho
thirty-sixth year of Her reign, did, for Herself, Her heirs and successors, 3

page_text: give and grant unto us, the said Frederick Carley Coxhead and James
John Miller, Her special license that we, the said Frederick Carley
Coxhead and James John Miller, our executors, administrators, and
assigns, or such others as we, the said Frederick Carley Coxhead and
James John Miller, our 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, excrcise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN MARINE STEAM ENGINES," upon the con-
dition (amongst others), that we, the said Frederick Carley Coxhead
and James John Miller, our executors or administrators, by an instru-
ment in writing under our or their hands and seals, or under the hand
and seal of one of us or them, should particularly 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 we, the said Frederick Carley Coxhead and
James John Miller, do hereby declare the nature of the said Invention,
and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement thereof,
that is to say :-
This Invention has for its object improvements in marine steam
engines.
In engines in which the steam is expanded many times, especially
when a small high-pressure cylinder discharges the steam into a large
low-pressure cylinder, as is the case in the engines known as compound
engines, there is difficulty in controlling the engines when from the
pitching of the vessel the screw is lifted out of the water, and so the
engines are relieved from their load. By means of a governor, or eveń
by the stop valve, the entry of fresh steam into the cylinder may be
prevented, but nevertheless the high vacuum in the condenser and the
steam and moisture already in the cylinders' and passages is sufficient to
cause the engines to make several rotations, and a dangerous velocity
may even be attained. To prevent this we employ a large valve, by
which air may be admitted to the condenser so as instantly to destroy.
the vacuum when necessary; and in order that this valve, which
"

page_text: requires considerable power to control it, may be operated with sufficient
rapidity we, connect with it a steam piston.
valve.
We prefer to apply the steam pressure to hold the valve in its seat
against the pressure of the atmosphere, so that when the governor by
opening a valve or cock removes the steam pressure air at once enters
this condenser. Or steam may be applied in other ways to control the
valve opening into the condenser; or in place of steam air or water
may be employed so as to ensure the rapid action of a
large,
Or an equilibrium valve may be employed, and then the pressure of the
air in one direction being balanced more or less completely by the
pressure in the opposite direction a large area for the admission of air
can be opened by the direct action of the governor, or of the hand lever
which works the stop valve.
In order that our said Invention may be most fully understood, and
readily carried into effect, we will proceed to describe the Drawings

page_text: admitting air to the condenser at once checks the speed of the engines.
The area of the valve 6 should be such as to admit air with sufficient
freedom. We have found an area of from two to three square inches.
per 100 horse power indicated to be suitable for large engines where the
condenser and pump are efficient, and for small engines the proportional
area should be larger.
°
Valves of the construction above described can only be worked so long
as the boiler pressure is maintained at about the pressure for which the
apparatus is constructed, but by the modification shewn at Figures 3
and 4 the apparatus is made available for a considerable range of working
pressure. Figure 3 is a vertical section and Figure 4 a plan. These
Figures shew the arrangement which we more especially prefer. The
piston d is not put immediately over the valve, but is connected with it
by a link e and bell-crank lever f, having its fulcrum upon the case a
at f¹. The link e is connected with the screw stem g, and by the nut g¹
thereon the joint between the link and the lever can be traversed along
a slot in the lever nearer to or further from the fulcrum f. i is a
graduated scale. In adjusting the apparatus the pointer g* upon the
stem g is brought to the graduation corresponding with the steam'
pressure in the boilers.
Figure 5 is a longitudinal section of another arrangement. Here the
valve b is held upon its scat by the pressure of the air, and is lifted when
required by steam (or it might be other fluid) acting upon the piston d.
When the valve 6 is required to lift, steam or fluid is admitted beneath
the piston by the small slide valve k, which may be connected with the
governor or may be otherwise moved.
The steam or fluid pressure may be applied both to shut and to open
the valve in the manner shewn at Figure 6. The air valve 6 there
shewn is of the gridiron form.
In the arrangement shewn in section at Figure 7 and in plan at
Figure 8, the pressure of the air upon the piston d is employed to
counterbalance the inward pressure of the air upon the valve b. The
piston in this case is made of somewhat larger area than that of the
valve b. When the small valve k is raised by the action of the governor
(or otherwise) the piston d is relieved from pressure (the space above it
being put into communication with the condenser) and then the un-
balanced pressure of the air beneath the valve b raises it.

page_text: The arrangement may be modified in the manner shewn by Figure 9.
Here the space above the piston d remains constantly open to the
atmosphere, and the valve k is dispensed with. In place thereof the
piston d and valve 6 are by a rod 7 connected directly with, and worked
by the governor;
or with a stop valve lever the parts are so pro-
portioned that the valve 6 is at all times nearly in equilibrium, and will
require but little power to work it beyond that expended in overcoming
the friction.
"
=
In place of balancing the pressure of the air upon the valve 6 by air
pressure acting in the contrary direction as here shewn, the balancing 1
of the valve and placing it in equilibrium may be effected by a spring, as
is shewn in Figure 10.
Having thus described the nature of our Invention, and the manner
of performing the same, we would have it understood that we claim as
our improvements in marine steam engines, the application of a valve to 1
admit air into the condenser, such valve being held to its seat by the
steam which is supplied to the engine and opening when the supply of
steam is checked, substantially as described.
We also claim the combination with the valve 6 for admitting air
into the condenser of a piston d, acted upon by steam or other fluid 2
pressure under the control of a small valve k, substantially as described.
We also claim the application of an equilibrium valve controlled by
the governor or connected with the stop valve to admit air to the
condenser of a steam engine, substantially as described.
In witness whereof, we, the said Frederick Carley Coxhead and 2
James John Miller, have hercunto set our hands and seals, this
Twenty-fifth day of January, in the year of our Lord One
thousand eight hundred and seventy-three.
FREDERICK CARLEY COXHEAD. (L.S.)
JAS. J. MILLER.
(L.S.)