IMPROVEMENTS IN STEAM ENGINES
Year: 1876

page_text: LETTERS PATENT to John Penn, junior, of Greenwich, in the County of Kent,
for the Invention of "IMPROVEMENTS IN STEAM ENGINES."
led the 31st March 1876, and dated the 28th January 1876.
the Commissioners of Patents on the 28th January 1876.
JOHN PENN, junior, of Greenwich, in the County-of Kent.
STEAM ENGINES."
"IMPROVEMENTS IN
The object of this Invention is to construct steam engines for marine use which
will combine economy in ordinary use with the capability on emergency of greatly.
increasing the power.
Three cylinders which may be of equal size are ranged side by side, and
connected to a three throwed crank shaft in the usual manner. In ordinary
working one of these cylinders receives steam direct from the boilers, and the
steam after working in this cylinder is admitted into the two other cylinders, and
passes thence into the condenser; but valves are so arranged that to meet an
emergency the steam can at once be led direct from the boiler into each of the
cylinders, and each cylinder then exhausts direct into the condenser, by which
means a greatly increased power is obtained; or the whole or a portion of the
exhaust steam may be passed up the chimney to increase the draught
In order that my Invention may be more clearly understood I will by way of
example describe more fully a set of marine engines designed in accordance with
the Invention.
The engine consists of three vertical cylinders of 62 inches diameter, and 3 feet 3
inclies stroke, each fitted with a side valve and expansion valve of the ordinary kind
with a variable cut-off. When in ordinary use it is a compound engine, the steam
being admitted first into the forward cylinder, which is the high-pressure cylinder at
60 lbs. pressure; the engines are provided with three stop valves as follows:-1. A
stop valve fitted to a passage, which when open permits the forward cylinder to
exhaust into the trunk, which supplies steam to the central and after cylinders.
2. A stop valve fitted to a passage, which when open allows steam to pass from the
main steam pipe into the trunk, which supplies steam to the central and after
cylinders. 3. A stop valve fitted to a passage, which when open allows the forward
cylinder to exhaust direct into the condenser.

page_text: When working as a compound engine the first stop valve is open, and the second
and third are closed, so that the forward or high-pressure cylinder may exhaust
from thence through the first stop valve into the two low-pressure cylinders, from
whence the steam passes into the condenser by the eduction pipes in the usual
manner. Under these circumstances the engine will make about 72 revolutions and
develope 2000 indicated horse-power with the utmost economy, the boilers being
very large for this power; the speed of the ship at this power may be, say, about 13
knots.
When it is desired to exert an increased power the only thing to do is to open
the second and third stop valves and to shut the first; the steam is then admitted
equally to all three cylinders, to the forward cylinder direct as before, and to the
central and after cylinder through the second stop valve, and the supply trunk, and all
three cylinders then exhaust direct into the condenser, each through its own eduction
pipe; thus 4000 indicated horse-power or double the former power is obtained, the
engines making about 90 revolutions, and the speed of the ship being increased to
16 knots. This greatly increased power is of course obtained at a slight sacrifice of
economy, the boilers and condenser being somewhat small for this power. The
engine itself however, will still be economical, as the steam by the variable expansion
valves will be cut off at about one-fourth of the stroke. The size of the piston rod,
connecting rod, and slide valve and gear is the same for all three cylinders, so that a
saving is also effected in the spare gear, as one piston cylinder cover or other part
relating to the cylinder will be sufficient instead of two as usually supplied to
compound engines.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said John Penn in the Great Seal Patent Office on the 28th July 1876.
JOIN PENN, junior, of Greenwich, in the County of Kent. "IMPROVEMENTS IN
STEAM ENGINES."
The object of this Invention is to construct steam engines for marine use, which
will combine economy in ordinary use with the capability on emergency of greatly
increasing the power.
Three cylinders, which may be of equal size, are ranged side by side, and
connected to a three throwed crank shaft in the usual manner. In ordinary.
working one of these cylinders receives steam direct from the boilers, and the steain
after working in this cylinder is admitted into the two other cylinders, and passes
thence into the condenser, but valves are so arranged that to meet an emergency
the steam can at once be let direct from the boiler into each of the cylinders, and
each cylinder then exhausts direct into the condenser, by which means a greatly
increased power is obtained or the whole or a portion of the exhaust steam may be
passed up the chimney to increase the draught.
In order that my Invention may be more clearly understood, I will by way of
example describe more fully with the aid of a Drawing a set of marine engines.
designed in accordance with the Invention.
The Drawing shows a horizontal section.
The engine in this example consists of three vertical cylinders, of 62 inches
diameter, and 3 feet 3 inches stroke, each fitted with a slide valve and expansion
valve of the ordinary kind, with a variable cut off. When in ordinary use it is a
compound engine, the steam being admitted first into the forward cylinder, which is.
the high-pressure cylinder at 60 lbs. pressure, the engines are provided with three
stop valves as follows:-1. A stop valve marked C on the Drawing fitted to a
passage which when open permits the forward cylinder to exhaust into the trunk,
which supplies steam to the central and after cylinders. 2. A stop valve marked
A on the Drawing, fitted to a passage, which when open allows steam to pass from
the main steam pipe into the trunk, which supplies steam to the central and after

page_text: cylinders. 3. A stop valve marked B on the Drawing fitted to a passage which when
open allows the forward cylinder to exhaust direct into the condenser.
When working as a compound engine the first stop valve is open, and the second
and third are closed, so that the forward or high-pressure cylinder may exhaust from
thence through the first stop valve, into the two low-pressure cylinders, from whence
the steam passes into the condenser by the eduction pipes in the usual manner.
Under these circumstances the engine will make about 72 revolutions and develope
2000 indicated horse-power, with the utmost or at any rate with a very high degree
of economy, the boilers being very large for this power; the speed of the ship
at this power if suitably constructed may be say about 13 knots.
When it is desired to exert an increased power the only thing to do is to open
the second and third stop valves and to shut the first. The steam is then admitted
equally to all three cylinders, to the forward cylinder direct as before, and to the
central and after cylinder through the second stop valve and the supply trunk, and
all three cylinders then exhaust direct into the condenser, each through its own
eduction pipe, thus about 4000 indicated horse-power or double the former power is
obtained, the engines making about 90 revolutions, and the speed of the ship being
increased to say about 16 knots. This greatly increased power is of course obtained
at a slight sacrifice of economy, the boilers and condenser being somewhat small for
this power. The engine itself however will still be economical as the steam by the
variable expansion valves will be cut off at about one-sixth of the stroke. The size
of the piston rod, connecting rod, and slide valve and gear is the same for all three
cylinders, so that a saving is also effected in the spare gear as one piston, cylinder
cover, or other part relating to the cylinder will be sufficient instead of two as
usually supplied to compound engines.
It will be understood that horizontal, trunk, and other engines may be similarly
constructed; I do not confine myself to the exact details shown on the Drawing,
but I claim the construction of steam engines substantially as described.
In witness whereof, I, the said John Penn, junior, have hereunto set my hand
and seal, this Twenty-fourth day of July, in the year of our Lord One
thousand eight hundred and seventy-six.
.
JOHN PENN, JR. (L.S.)