IMPROVE- MENTS IN PISTONS FOR STEAM ENGINES
Year: 1862

page_text: LETTERS PATENT to George Scoville, of Woods' Hotel, Furnival's Inn,
in the City of London, Attorney-at-Law, for the Invention of "IMPROVE-
MENTS IN PISTONS FOR STEAM ENGINES:"-A communication from abroad
by Augustus James Scoville, and Augustus Hervey de Clercq, of Bloom-
ington, Illinois, United States of America.
Sealed the 20th June 1862, and dated the 22nd April 1862.
PROVISIONAL SPECIFICATION left by the said George Scoville, at the
Office of the Commissioners of Patents, with his Petition, on the 22nd
April 1862.
I, GEORGE SCOVILLE, of Woods' Hotel, Furnival's Inn, in the City of
London, Attorney-at-Law, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN PISTONS FOR STEAM ENGINES," to be as follows:-
The object of this Invention is to simplify and perfect the use and applica-
tion of metallic packing for pistons of steam engines, and to dispense with
the use of springs or other mechanical contrivances for adjusting and regu-
lating such packing. This object is effected by substituting steam by means
of a simple mechanical arrangement for the springs or equivalent mechanical
contrivances usually employed for the purpose.
Instead of the rings in
common use in locomotive pistons which are ordinarily made of brass and

page_text: Babbitt metal, and are consequently very expensive, cast-iron rings may be used.
As the rings in common use are so well known it will only be necessary to say
that in locomotive engines ordinarily, the two outside rings are made alike
about three-quarters of an inch thick, and wide enough so that the two when
in position will fill the space between the flange of the piston head and the
follower, and work freely. Each ring is severed or cut across diagonally, so
as to allow expansion when pressed upon from the inside. The inside ring in
the piston of the ordinary locomotive engine is usually one quarter of an inch
thick and of the same width as both the outside rings, cut open in the same
manner, and when in position between the flange of the piston head and the
follower rests on the inside surface of the outside rings, the openings in all the
rings being at different places, so as to break joints. Instead of springs or
any other mechanical contrivance for pressing the rings out against the cylinder
a fourth ring of cast iron or other metal is employed, and may be termed a
valve ring. This ring is placed within the inside ring; the width of this valve
ring when finished is a very little less than the distance between the flange of
the piston bead and the follower, say one thirty-second of an inch less, and it
is turned off on the edges in a lathe. This valve. ring is made with bosses on
the outside, and large enough so that when in position the bosses will touch
the inside ring. The object of these bosses is to strengthen the valve ring
without, making it heavy, and to form spaces between the valve ring and the
inside ring so as to allow the free action of the steam on the inside ring, and
at the same time to support the valve ring, while resting on the inside ring
holes are made in the flange ring for the admission of steam-into the spaces
behind the packing rings. It will be obvious that as the steam is let into one
end of the cylinder it will pass through the small holes in the flange of the
piston head or follower, opening against the bosses on the valve ring, and
pressing the valve ring over against the holes on the opposite side will thus
close those holes and be prevented from escaping or blowing through; the
pressure of the steam must consequently be exerted on the inside ring and
thereby be brought to bear upon the outside rings and cause them to expand
against the side of the cylinder and forming a perfectly fitting piston. When
the piston is forced to the other end of the cylinder and the steam is let in at
that end the action of the valve ring is reversed and the pressure of the steam
on the rings is exerted from the other side of the piston head. Thus the valve
ring in its operation with the holes above described through the piston flange
and follower is simply a valve or series of valves for the purpose of admitting
steam into the piston head, and is made in the form aforesaid so as to present

page_text: a considerable surface against the flange of the piston head and the follower
to prevent wear. The valve ring may be made with a flange on each end of
the same width as the combined thickness of the ring and boss, with holes
through the ring between the bosses to allow the free passage of steam to and
against the inside ring. The advantages of this Invention herein described
consist in its being easily and cheaply applied to the packing of pistons in steam
engines already made in the ordinary way with springs, and in securing a
uniform and even pressure upon the rings that form the packing of the piston,
causing them to wear smoothly and evenly, not cutting the cylinders, and con-
sequently lasting much longer than the metallic packing in ordinary use. It
is also durable and not liable to get out of order, and is peculiarly valuable in
locomotive engines, as when running down grade or whenever the steam is
shut off; the piston works freely and without friction, as is not the case when
the packing is set out by any other means than the steam itself.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Scoville in the Great Seal Patent Office on the
22nd October 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE'
SCOVILLE, of Woods' Hotel, Furnival's Inn, in the City of London, Attorney-
at-Law, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of April, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said George Scoville. Her special license that I, the said George Scoville, my
executors, administrators, and assigns, or such others as I, the said George
Scoville, 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 PISTONS
FOR STEAM ENGINES," being a communication from abroad, upon the condition
(amongst others) that I, the said George Scoville, by an instrument in writing
under my hand and seal should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be per-

page_text: formed, 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 George Scoville, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the Drawing hereunto annexed, and to the
letters and figures marked thereon (that is to say):-
:-
The object of this Invention is to simplify and perfect the use and applica-
tion of metallic packing for pistons of steam engines, and to dispense with the
use of springs or other mechanical contrivances for adjusting and regulating
such packing..
I shall proceed to describe the construction and operation of the improved
piston as applied to the cylinders of locomotive engines, as it is in such engines
and in others in which the pistons have a very rapid movement communicated
to them that this Invention is most valuable. The packing rings should be
three in number, two commonly known as the outside rings next the cylinder,
and one known as the inside ring, equal in width to both the outside rings,
and lying on the inside of them. These rings are of iron, brass, or other
metal, but in constructing pistons according to the improvements hereafter
described iron is found to work as well as any other metal, and is also the
cheapest. The packing rings are kept expanded against the inside of the
cylinder by means of the pressure of steam instead of by springs as heretofore.
The two outside packing rings are of similar construction, and are about
three-quarters of an inch thick, and wide enough so that the two when in
position will fill the space between the two plates of the piston and work freely
there. One of these plates is known as the flange of the piston head and
other as the follower. Each packing ring is cut across diagonally, thereby
severing the ring so as to allow it to expand when pressed upon from the
inside by the steam. The inside ring is about one-fourth of an inch thick
and of the same width as both the outside rings, and is also cut open, though
not diagonally, and when in position between the flange of the piston head
and the follower, rests' on the inside surface of the outside rings, the openings
in all the rings being at different places so as to break joints. I then make
of cast iron or other metal a fourth ring, which may be termed a valve ring,
and which is placed within the packing rings above described, and is con-
structed as follows, to wit, the width of this valve ring when finished is a very
little less than the distance between the flange of the piston head and the

page_text: follower, say one thirty-second of an inch, or even less than that, and it is
turned off on the edges in a lathe, and finished by grinding or otherwise, so
as to make it perfectly smooth and even. This valve ring is made with bosses
on the outside large enough so that when it is in position in the piston the
bosses will touch the inside ring. Ten of these bosses will be a sufficient
number, but there may be less or more according to the size of the cylinder.
The object of these bosses is to strengthen the valve ring without making it
too heavy, and to form spaces between the valve ring and the packing rings to
allow the free action of the steam on the inside ring.
In the accompanying Drawing, Fig. 1 represents an end view of the valve
ring, showing the bosses a, a; Fig. 2 represents a side view of the same ring.
The ring itself should be about one-fourth of an inch thick, and the bosses
about three-eighths of an inch thick and an inch wide. In Fig. 1 the letters
b, b, shew small guides cast on the inside of the valve ring, which are to be
finished to fit corresponding grooves in the bosses of the piston head, as shewn
at c, c. Fig. 3. These guides are to keep the valve ring in its proper position
and prevent its revolving. To allow the introduction of the valve ring in the
ordinary piston it is necessary to turn off the bosses of the piston head B, 13;
Fig. 3, which represents an end view of the piston head.
To admit the steam within the piston head, small holes, say one-fourth of
an inch in diameter, are drilled through the flange of the piston head and
through the follower, as shown by the letters d, d, in Fig. 3, directly over or
against the bosses a, a. As the steam is let into one end of the cylinder, it
will pass through these small holes on that side of the piston head, and
pressing the valve ring over against the holes on the opposite side, will thus
close those holes and be prevented from escaping or blowing through: The
pressure of the steam must consequently be exerted on the packing rings;
thereby expanding them against the inside of the cylinder and forming a
perfectly fitting piston. When the piston is forced to the other end of the
cylinder and the steam let in on the opposite side of the piston, the action of
the valve ring is reversed, and the pressure of the steam on the packing rings
is exerted from the other side of the piston head.
In the accompanying Drawings Fig. 4 shews an end view of the piston head
with the follower removed and the rings in position; B; B, are the bosses of
the piston head. The letters b, b, show the guides on the valve ring fitting in
the
in the bosses of-the piston head. The bosses on the valve ring
are shewn at a, a. The inside ring is marked f, and the outside rings ġ and h!
Fig. 5 represents a sectional view of the piston head with the rings all in
grooves
"

page_text: position and the different parts designated by the same letters as in Fig. 4.
In Fig. 5 both the outside rings are shewn and are marked g and h. Holes
for the admission of steam against the edge of the outside or packing rings g
and h are shewn at e, e. By allowing steam to press against the edges of the
packing rings these latter will be forced forward against the holes d in the
flange or follower of the piston according to the direction in which the piston
is proceeding, and will thus close the holes d and prevent the steam from
escaping from the inside of the piston and getting in front of the piston. The
holes e, e, may be dispensed with and the same result obtained by cutting out
notches in the edge of the flange head or follower as shewn in Fig. 8 and by
dots in Fig. 6, or steam may be admitted to press on the edge of the packing
rings g and by turning the flange head and follower of the piston a little
smaller in diameter than the packing rings, as shewn in the side view, Fig. 7.
The follower is secured to the piston head by means of bolts i, i, whereby all
the parts are held together. Small spaces or openings k, k, are left between
the flange ring and the packing rings for the admission of steam past the valve
ring. The valve ring may be constructed with a flange on each end of the
same width as the combined thickness of the ring and boss, and made with
holes through the ring between the bosses to allow the free passage of the
steam to and against the packing rings g, h. In such case the bosses would
serve to strengthen the flanges of the valve ring and would not be necessary if
those flanges were made sufficiently strong of themselves. When the valve
ring is made with flanges as aforesaid, it is not necessary to have the guides
shown by b, b, Fig. 1, on the grooves shown by c, c, Fig. 3.
The small holes, one-fourth of an inch in diameter, shown by the letters e, e,
Fig. 3, are drilled through the flange of the piston head and also through the
follower near the edge, say one-fourth of an inch therefrom, for the purpose of
admitting steam against the edges or sides of the outside rings, which are
thereby pressed over against the opposite side of the piston head and the steam
is prevented from escaping or blowing through from the inside of the piston
head between the sides of the packing rings and the piston plates. The same
result is obtained by the modification shewn in Figures 6, 7, and 8, and
already described.
In order to keep the piston in the centre of the cylinder as the packing
rings wear away, and also to keep. the rings, expanded as they become worn,
without making any considerable pressure on the cylinder when the engine is
working with little or no steam, a supporting stud, shewn at M, Fig. 6, is
introduced. To this end a hole is drilled in the under side of the hub or centre

page_text: of the piston head to admit the head of the screw n; this screw enters the
block o, and passes down within it to the v-shaped bottom piece. The
block has a thread cut within it to receive the screw n, which passes through
an opening cut in the valve ring large enough to allow the ring free play, and
yet not to weaken it. The lower part of the block o is a very flat V-shape,
with the apex or point of the V inserted in a similar shaped space or opening
on the inside ring, the V being made to just fill the space between the
plates of the piston, or, in other words, covering the entire opening of the
inside ring. The lower faces of the V should be ground or finished to smooth
even surfaces and be carefully fitted to the edges of the ends of the inside ring.
It will now be understood that as the packing rings wear away and expand, the
point of the V will be pressed down by the weight of the piston between the
ends of the inside ring, thus retaining the expansion of the rings without causing
undue friction on the inside of the cylinder and preventing the sudden and
violent expansion of the rings by the action of the steam, whereby rings of
cast iron or other brittle metal are liable to be broken.
With pistons constructed as herein described, an uniform and even pressure
upon the packing rings is obtained, thereby causing them to wear evenly and
Simoothly, while the friction of the piston in the cylinder is greatly reduced
whenever it runs with the steam wholly or partially shut off as in locomotives
running down an incline or otherwise. By this Invention, also, the method
of admitting steam into the piston head by means of the valve ring is so siniple,
and the valve ring itself is so durable, that there is little liability of the piston
getting out of order or needing repairs. The packing rings and the cylinders
are found to wear less with these improvements than when the rings are
expanded by means of springs, and the action of the steam in and around the
piston is found to keep it clean and prevent the accumulation of dirt in the
cylinder or piston.
'
Having now described this Invention of "Improvements in Pistons for Steam
Engines," and having explained the manner of carrying the same into effect,
I would observe that although I have described and shewn the Invention as
more particularly applicable to the pistons of locomotive engines, the Invention
is also applicable to the pistons of other steam engines. I do not therefore
mean or intend to confine myself to any particular kind of engine, nor do I
intend to claim the broad principle of causing the packing rings to expand by
means of the pressure of steam admitted within the piston, but that which I
consider to be new and therefore wish to claim as the Invention secured to me
by Letters Patent as aforesaid, is the mode herein set forth of admitting

page_text: steam to the interior of the piston and causing the same to act on the packing
rings. I claim particularly the use of the valve,ring in combination with the
perforated flange head and follower, and also the combination or construction
of parts herein shewn, or any mere modification thereof whereby the packing
rings may be kept pressed up against the flange head or follower of the piston
(according to the direction in which the piston. may be travelling) so as to
prevent the escape of steam through or past the packing rings.
In witness whereof, I, the said George Scoville, have hereunto set my
hand and seal, the Twenty-eighth day of May, in the year of our
Lord One thousand eight hundred and sixty-two.
GEORGE SCOVILLE. (L.8.)