IMPROVEMENTS IN STEAM ENGINES
Year: 1866

page_text: LETTERS PATENT to Charles Talbot Porter, of No. 12, Winfield Terrace,
Old Trafford, in the County of Lancaster, Engineer, for the Invention
of "IMPROVEMENTS IN STEAM ENGINES."-Partly a communication from
abroad by John Franklin Allen, of New York City, United States of
America.
Sealed the 19th February 1867, and dated the 25th August 1866,
PROVISIONAL SPECIFICATION left by the said Charles Talbot Porter
the Office of the Commissioners of Patents, with his Petition, on the
25th August 1866.
I, CHARLES TALBOT PORTER, of No. 12, Winfield Terrace, Old Trafford, in
the County of Lancaster, Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN STEAM ENGINES," partly a communication,
to be as follows:-
The said improvements relate, firstly, to the construction of an equilibrium
slide valve, to the means. for preventing the pressure of steam upon the said
valve, and keeping it tight upon its bearing surfaces.
And, secondly, to the means for diminishing the loss of heat by conduction
from the cylinders of steam or other motive-power engines. The said slide

page_text: valve is more especially designed for use on steam engines in which there are
separate valves for the admission and exhaustion of the steam at each end of
the cylinder, motion being communicated to each independently. The object
desired to be attained by the novel construction of the slide valve is the direct
admission of steam into one port through four passages which are opened and
closed simultaneously by the said valve sliding in equilibrium. The valve is
constructed in the form of an oblong frame whose surfaces on each side are
parallel, one side being in contact with the port face, and the other side with
the face of a bridge or plate which takes off the pressure from the back of
the valve; the said bridge rests upon shelves or projections upon the port face
which are so formed and fitted that the valve will work steam-tight between the
two surfaces without being pressed in either direction by the force of the
steam. The bridge is made of sufficient strength to ensure its perfect rigidity
under all pressures, and is advantageously constructed with its back in the
form of an arch; the bearing surfaces of the shelves upon which the bridge
rests are by preference provided with fitting strips which enable the said
shelves to be more readily and equally reduced when it is necessary from time
to time to adjust them to the slight decrease which takes place from wear in
the thickness of the valve. The bearing shelves are so arranged that a space
is left between them and the sides of the valve casing to ensure the expan-
sion arising from the heat of the steam affecting all parts equally. On the
face of the bridge, in contact with the valve, a recess is formed of the same
length and width as and arranged opposite to the steam port; the width of
the valve and the opening therein are so proportioned to the width of the
port and the recess in the bridge that when the end of the valve is brought
to the lower edge of the port the admission of steam to the said port is com-
pletely cut off, but when the valve is moved towards the opposite edge of the
port four apertures are formed simultaneonsly for the entrance of the steam
one on each of the lower edges of the valve, two being on one face and two
on the other face thereof. The effective area of the port for the admission of
steam is increased till the side of the valve is in the middle thereof, at which
point all the four apertures are open to an equal extent. The valve is pro-
vided with a boss or barrel extending across the width thereof, which is bored
out for the passage through it of the valve rod or spindle. In steam engines
and other motive-power engines as usually constructed the cylinder is in
direct contact with the foundation plate; this establishes a communication
for the heat, which thereby escapes rapidly from the cylinder, causing a waste
of heat and needless consumption of fuel; to prevent this escape, and thereby
more effectually utilize the heat in the cylinder sheets or strips of compressed

page_text: paper, millboard, papier maché, or other suitable non-conducting substance
are interposed between the surfaces of the cylinder and foundation plate where
these would otherwise be in contact, and also around the bolts connecting the
same.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Talbot Porter in the Great Seal Patent Office on
the 25th February 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
TALBOT PORTER, of No. 12, Winfield Terrace, Old Trafford, in the County of
Lancaster, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fifth day of August, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Charles Talbot Porter, Her special licence that I, the said Charles Talbot
Porter, my executors, administrators, and assigns, or such others as I, the said
Charles Talbot Porter, 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 of "IM-
PROVEMENTS IN STEAM ENGINES," upon the condition (amongst others) that I,
the said Charles Talbot Porter, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals, 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 I, the said Charles Talbot Porter, 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, reference being had to the accompanying Sheets of Drawings
forming a part of this Specification :- .
The said improvements relate, firstly, to the construction of an equilibrium
slide valve, and to the means for preventing the pressure of steam upon the
said valve, and for keeping it steam-tight upon its bearing surfaces.

page_text: And, secondly, to the means for diminishing the loss of heat by conduction
from the cylinders of steam engines; the said slide valves are more espe-
cially designed for use on steam engines in which there are separate valves
for the admission and exhaustion of the steam at each end of the cylinder,
each valve having an independent motion. The object desired to be attained
by the novel construction of the slide valve is the direct admission of steam
into one port through passages on its opposite sides, which are opened and
closed by the sliding of the said valve.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a longitudinal vertical section through the cylinder and valve
casing of a steam engine of the above-mentioned construction; Figure 2 is a
transverse section on the line x, x, Figure 1.
Figure 3 is a plan of one of my improved equilibrium valves; Figure 4
is a plan of the seating of the said valve; Figure 5 is a plan of a plate or
bridge for preventing the pressure of the steam on the same; Figure 6.
represents the fitting strips employed for adjusting the said plate.
Like letters indicate the same parts in each of the Figures.
A is the cylinder, and B the slide casing or steam chest, which is secured
to the jacket C by the bolts and nuts D. The induction ports E, E¹, are
formed in the port face F, and communicate with each end of the cylinder
in the usual manner, as shewn in Figure 1. The valves G, G¹, which are
fitted to slide on the port faces F serve only for admitting and cutting off
the steam, the additional valves H being provided to control the escape
or exhaust of the same. These valves H slide upon the face cover the
exhaust ports I, and are so arranged and operated as to close the latter, when
the communication between the corresponding end of the cylinder and the
steam chest is open. The valves G, G¹, are each constructed in the form of an
oblong frame whose surfaces a, a¹, are parallel; one of these surfaces a is fitted
to slide upon the port face E, while the other surface a¹ works in contact
with the under surface 6 of the plates or bridges J, which prevent the pressure
of the steam on the back of the valves G, G¹. Each of the latter is constructed
with a boss G³ through which the rods d, d, pass, the said rods being secured
therein by the adjusting nuts e. The valves G and G¹ are operated by the
rods d, d', while the exhaust valves H are operated by the rod f; all of the
said rods being connected to separate levers on the rocking shaft or other
convenient working part of the engine. The plates or bridges J are made of
cast iron or other suitable metal, and of sufficient strength to remain perfectly
rigid and true with the surface a¹ of the valves G, G¹, under the highest
.

page_text: pressure to which they will be subjected. The said bridges are advantageously
constructed with the back curved or arched, as represented in Figure 2. A
recess g is formed in each of the plates J; and is made to correspond in length
and width with the ports E, E¹. The recess g is formed in each of the plates
J in such a position that when the latter are properly arranged the said recess
will lie exactly opposite the corresponding port, as shown in Figure 1. The
plates or bridges J are supported upon shelves or projections K, which are
formed or otherwise secured upon the port face F. The shelves K are by
preference provided with the fitting strips K', which are readily reduced in
thickness when it becomes necessary to lessen the distance between the port
face F and the surface 6 of the plates J; this adjustment is rendered necessary
from time to time by the wearing of the valves G, G', though this wearing is
greatly diminished by my improved method of construction. The surfaces h
of the strips K' are parallel with the port face F, and the shelves with the
strips are of such a height from the said face that the valves G. G', will slide
freely but perfectly steam-tight between the face F and the surface 6 of the
plates or bridges J without being forced by the steam against either of these
surfaces. The bearing shelves K are so arranged that a space is left between
them, and the sides of the casing or chest B. By this means the expansion
arising from the heat of the steam is caused to affect equally the casing, the
port face, and other parts in connection with the same. The plates or bridges J
are firmly secured upon the shelves K by the bolts h³, or other suitable means.
The width of the valves G, G', and that of the apertures i in the same, is so
proportioned to the width of the ports E, E, and recesses g, that when each
of the said valves has travelled in one direction to the edge of the port over
which it slides the admission of steam to the latter is completely cut off, but
when the said valve is moved in the opposite direction four apertures are
formed simultaneously, two of the said apertures being between the edges of
the valve and those of the port face F, and the other two between the opposite
edges of the said valve and the plate or bridge J. In Figure 1 the valve G is
shown closing the port E, while the valve G¹ is moving towards the forward
end of the cylinder A and opening the four apertures j, k, l, m, which all
communicate with the port E', as indicated by the arrows in the same Figure;
these apertures which equal the effective area of the said port increase in
width as the valve moves forward till the edge g¹ of the valve G' reaches the
middle of the port, at which point the areas of all four of the apertures j, k, l, m,
are equal. The construction of the valves G, G¹, and plates J, and their
arrangement within the casing B, may be varied in any manner which provides
or the sliding of the said valves in equilibrium, and the simultaneous opening

page_text: and closing thereby of apertures on their opposite sides communicating with
one port.
The steam engines and other motive-power engines, as usually constructed,
the cylinder is in direct contact with the foundation plate or other means of
support, and the heat thereby escapes rapidly from the cylinder. The quantity
of heat thus wasted causes the consumption of a much larger quantity of fuel
than would otherwise be necessary. To prevent this escape, and thereby more
effectually utilize the heat in the cylinder, the contact of the same with
the foundation plate or other support is prevented by the introduction of non-
conducting substances between the bearing surfaces, and by the reduction of
the said surfaces to the smallest possible area. In an engine of the con-
struction represented in the accompanying Drawings the surfaces n of the
cylinder cover are supported upon the corresponding surfaces o, and air is
confined within the space p. Strips of compressed paper, millboard, papier
maché, or other suitable non-conducting substances may be interposed
between the surfaces n and o, and also around the bolts q connecting the
cylinder with the foundation plate.
Having thus fully described my said improvements, and shown how the
same may be conveniently and advantageously carried into practice, I wish it
to be understood that I do not confine myself to the exact details herein
described and illustrated, but I claim,-.
First, a skeleton equilibrium valve which slides between two bearing sur-
faces and opens one or more passages on its opposite sides communicating
with one port.
Second, the valves G, G', plates J, and shelves K, constructed, combined,
and operating for the purposes and substantially in the manner set forth.
Third, preventing the loss of heat from the cylinder, substantially in the
manner set forth.
In witness whereof, I, the said Charles Talbot Porter, have hereunto
set my hand and seal, this Twenty-third day of February, in the
year of our Lord One thousand eight hundred and sixty-seven.
CHARLES TALBOT PORTER. (L.S.)
Witness,
W. ROBT. LAKE,
8, Southampton Buildings, W.C.