IMPROVEMENTS IN METALLIC PISTONS
Year: 1858

page_text: LETTERS PATENT to John Arnold, of Newton Moor, near Hyde, in the
County of Chester, Engineer, for the Invention of" IMPROVEMENTS IN
METALLIC PISTONS."
Sealed the 20th August 1858, and dated the 25th February 1858.
PROVISIONAL SPECIFICATION left by the said John Arnold at the
Office of the Commissioners of Patents, with his Petition, on the
25th February 1858:
I, JOHN ARNOLD, of Newton Moor; near Hyde, in the County of Chester,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN METALLIC PISTONS," to. be as follows:-
My improvements are applicable to the pistons of steam and other engines,
and to pumps and similar apparatus where a reciprocating piston works in a
cylinder.
My improvements consist in the form, construction, and arrangement of the
packing rings and springs.
A ring is first made to fit the cylinder; -this ring is cut in two, obliquely to
form two rings, which are each cut to allow them to expand to the sides of the
cylinder into which the piston is to fit; the cut being made at the deepest side
of each ring. These two rings are arranged between the two plates of the

page_text: piston, so that the deep part of one ring is over the shallow part of the other
ring, and a spring ring is placed in the inside of them to force them
outwards.
With this construction and arrangement the packing rings when expanded
press close both against the sides of the cylinder and the piston plates, there
being both a lateral and vertical action, the vertical action arising from the
oblique or incline form of the packing rings.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Arnold in the Great Seal Patent Office on
the 24th August 1858.
TO ALL TO WHOM THESE. PRESENTS SHALL COME, I, JOHN
ARNOLD, of Newton Moor, near Hyde, in the County of Chester, Engineer,
send greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fifth day of February, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me;
the said John Arnold, Her especial licence that I, the said John Arnold,
my executors, administrators, and assigns, or such others as I, the said
John Arnold, 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 METALLIC PISTONS," upon the condition (amongst others) that I, the said
John Arnold, 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.
+4
NOW KNOW YE, that I, the said John Arnold, 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 Drawing (that is to say) :-
My improvements are applicable to the pistons of steam and other engines,

page_text: and to pumps and similar apparatus where a reciprocating piston works in
a cylinder.
My improvements consist in the form, construction, and arrangement of
the packing rings and springs.
According to my Invention, a ring is made of sufficient breadth or depth
to form the two packing rings; it is turned to fit the bore of the cylinder
for which it is intended, the ring is then cut obliquely to form two rings, which
are each cut at the deepest side to allow them to expand or be expanded
against the sides of the cylinder. The two rings are arranged between the
two plates of the piston, so that the deep part of one ring is over the shallow
part of the other ring, and a spring ring is placed inside of them to force
them outwards.
With this form, construction, and arrangement, the packing rings keep
close against each other and when expanded press close both against the sides
of the cylinder and the piston plates, there being both a lateral and vertical
action, the vertical action arising from the oblique or incline form of the
packing rings.
The annexed Drawing, "representing an eight-inch piston, full size, will
elucidate the preceding description.
Fig. 1 represents a plan view of a piston with the upper plate or cover in
its place; Fig. 2, a plan view with the cover or upper plate removed; Fig. 3,
a vertical section on a line from y to z, Fig. 2; Fig. 4, a section of one of the
packing rings cut in a line passing from the deepest to the shallowest part of
the ring; and Fig. 5, an edge view of one of the packing rings. The piston
rod is marked a, the boss plate b, the cotter by which it is secured to the
piston rod c, the upper piston plate or cover d, the bolts by which it is
secured to the boss plate are marked e, the packing rings f, and the spring
ring is marked g. The packing ring is divided into two parts, by a lathe, the
ring to be cut being secured at the required angle on the face plate of the
lathe. The spring ring is the thickest at the side opposite the cut. When
constructed it is first turned in a lathe roughly to the size, then a segment of
it is cut out of such length as will give sufficient expansive force when the
ends of the ring are in contact or nearly so; when this is done, the ends of
the rings are drawn and secured together, and the ring is turned and finished
to fit the packing rings exactly, and when this is accomplished the fastening
which holds the two ends of the ring is removed, and the ring is free to
expand. The cut in the spring ring is placed at a point between those
formed in the packing rings, as will be seen in Fig. 2.

page_text: I have now particularly described the nature of iny Invention, and the
manner in which it may be carried into effect, and wish it to be understood
that. I claim as my Invention, metallic pistons for steam and other engines,
pumps, and similar apparatus where a reciprocating piston works in a cylinder,
combining spring and packing-rings of the form, construction, and arrange-
ment herein-before described, particularly the oblique form of the packing
rings and their arrangement.
In witness whereof, I, the said John Arnold, have hereunto set my hand
and seal, this Twenty-third day of August, in the year of our Lord
One thousand eight hundred and fifty-eight.
JOHN ARNOLD. (L.S.).