IMPROVEMENTS IN METALLIC PISTONS
Year: 1872

page_text: LETTERS PATENT to Jacob Goodfellow, of Blackburn, in the County of
Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN METALLIC
PISTONS."
Sealed the 8th October 1872, and dated the 16th May 1872.
PROVISIONAL SPECIFICATION left by the said Jacob Goodfellow at the
Office of the Commissioners of Patents, with his Petition, on the
16th May 1872.
I, JACOB GOODFELLOW, of Blackburn, in the County of Lancaster,
Engineer, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN METALLIC PISTONS," to be as follows:--
My Invention relates to pistons having expanding metallic packings,
and consists more particularly in improvements in a former Invention
for which Her Majesty's Royal Letters Patent, bearing date the Twenty-
eighth day of December, in the year One thousand eight hundred and
In the said Invention an inner
sixty-eight, have been granted to me.
helical ring was surrounded by a helically cut ring of a double wedge
shape in cross section.

page_text: My present Invention consists in the first place in making the said
inner helical ring outwardly of a conical form, that is to say of a wedge
shape in cross section, the inner surface of the said double wedge ring
being turned to correspond to the conical form of the said inner ring.
The said inner ring is made of less depth than the said double wedge
ring, and the pressure it exerts upon the said double wedge ring may be
increased when desirable by moving it deeper or farther into the said
double wedge ring.
This operation may be effected either by means of screws or by similar
means, or by placing packings between the piston cover and the broader
edge of the said inner ring.
My Invention further consists in an improvement in the helical form
of the said rings. When cutting helical piston rings it is usual to make
the cut extend two or more times around the central axis of the ring.
When cutting the said rings I in each case make a cut extending only
partly around the said central axis, as for example I leave uncut a
portion of the ring equal in length in some cases to about one-twentieth
of the circumference of the said ring.
I prefer to cut one of the two rings in each piston into a right-hand
helix, and the other ring into a left-hand helix.
The said inner helical rings may also be employed in connexion with
"double wedge" rings not helically cut.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Jacob Goodfellow in the Great Seal Patent Office
on the 16th November 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JACOB
GOODFELLOW, of Blackburn, in the County of Lancaster, Engineer, send
greeting.
2
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of May, in the year of 3
our Lord One thousand eight hundred and seventy-two, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Jacob Goodfellow, Her special license that

page_text: I, the said Jacob Goodfellow, my executors, administrators, and assigns,
or such others as I, the said Jacob Goodfellow, my executors, adminis-
trators, 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 METALLIC PISTONS,"
upon the condition, amongst others, that I, the said Jacob Goodfellow,
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 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 Jacob Goodfellow, 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 and accompanying Drawings, that is to say :-
My Invention relates to pistons having expanding metallic packings,
and consists principally in improvements in a former Invention for
which Her Majesty's Royal Letters Patent, bearing date the Twenty-
eighth day of December, in the year One thousand eight hundred and
sixty-eight, have been granted to me. In the said Invention an inner
helical ring was surrounded by a helically cut ring of a double wedge
shape in cross section.
My present Invention consists in the first place in making the said
inner helical ring outwardly of a conical form, that is to say of a wedge
shape in cross section, the inner surface of the said double wedge ring
being turned to correspond to the conical form of the said inner ring.
The said inner ring is or may be made of less depth than the said double
wedge ring, and the pressure it exerts upon the said double wedge ring
may be increased when desirable by moving it deeper or farther into the
said double wedge ring. This operation may be effected either by means
of screws or by similar means, or by placing packings between the piston
cover and the broader edge of the said inner ring.
My Invention further consists in an improvement in the form of
helical piston rings. When cutting helical piston rings it is usual to

page_text: make the cut extend two or more times around the central axis of the
ring. When cutting the said rings I in each case make a spiral cut
extending only partly around the said central axis.
And in order that my said Invention may be fully understood I will
now refer to the accompanying Sheet of Drawings illustrative of my
methods of carrying the same into practical effect, and marked with
letters of reference, corresponding letters indicating the same parts in the
various Figures.
In the said Drawings Fig. 1, drawn about one-quarter of the full size,
represents a vertical section of a piston constructed in accordance with
my said Invention. In this example a is the piston block; b is the
cover or "junk ring;” c, c, are two ordinary split rings; d is a double
wedge ring split in manner according with my said former Invention, or in
manner herein-after to be described; and e is the aforesaid inner helical
ring. The inner surface of the ring d is turned to a conical shape, and
the outer surface of the ring e is turned to correspond, so that by
pressing down the ring e by means of screws f, f, or by any other
suitable means which may be adopted, the ring d is expanded and
the piston becomes a tighter fit in its cylinder. The parts are so pro-
portioned as that the piston is when new a sufficiently tight fit when
worked with one edge of the ring e projecting beyond the ring d, as
shown in the Drawing. When it becomes desirable to tighten the piston
the ring e is pressed down into the ring d, as herein-before mentioned.
The ring e may also be cut in manner according with my said former
Invention or with my present Invention. I prefer that one of the rings
d and e shall be split with a right-hand spiral or helical cut, and the
other of the said rings with a left-hand cut.
My present improved method of cutting piston rings is illustrated by
Figs. 2 to 7, both inclusive. Figs 2 and 3 represent the said ring d;
Fig. 3 being a plan of the said ring. The said ring is in this example
split by a spiral cut extending from 9 to h, that is to say extending
around about two-thirds of the circumference of the said ring, the
remaining one-third part being left uncut. I have found by practice
that rings so cut are very suitable, and preserve their circular shape
under varying degrees of compression in a very satisfactory manner.
The proportion which the length of the uncut part of the ring bears to
the cut part may however be varied as preferred or found to be suitable.

page_text: In Figs. 4 and 5 a ring is represented as being split with a spiral cut
extending around about nineteen-twentieths of the circumference, the
portion from i to k, that is to say one-twentieth of the circumference,
being left uncut.
Although I have taken the double wedge ring d as an illustration I
do not confine the application of my improvement to this form of ring, as
it is or may be applicable to other forms of piston rings.
Figs. 6 and 8 illustrate the application of this part of my Invention
to an air pump bucket, Fig. 6 representing a vertical section of such a
bucket. In this example the packing consists of only one spring ring 1,
represented in edge view at Fig. 7 and in plan at Fig. 8. The said ring
is split with a single spiral or helical cut extending around about two-
thirds of the circumference of the said ring. The said ring is sprung
into a groove turned around the said bucket. A bucket so formed is
much more simple and less liable to derangement than ordinary air
pump buckets. I do not however confine myself to the use for such a
purpose of only one ring split in the manner described.
Having now fully described and indicated the nature of my said
Invention, and the manner in which I carry the same into practical
effect, I would in conclusion have it to be distinctly understood that I
claim as my Invention,―
First. The combination of piston rings formed, fitted, and arranged
substantially as herein-before set forth, and as indicated by Figure 1 of
the accompanying Drawings.
And lastly. The employment of piston rings when split or cut in
manner substantially as herein-before set forth and indicated.
In witness whereof, I, the said Jacob Goodfellow, have hereunto set
my hand and seal, this Fifteenth day of November, in the year
of our Lord One thousand eight hundred and seventy-two.
JACOB GOODFELLOW. (L.S.)