IMPROVEMENTS IN THE CONSTRUCTION OF METALLIC PISTONS
Year: 1856

page_text: LETTERS PATENT to James Knowles, of Eagley Bank, near Bolton-le-
Moors, in the County of Lancaster, Coal Proprietor, for the Invention
of "IMPROVEMENTS IN THE CONSTRUCTION OF METALLIC PISTONS."
PROVISIONAL SPECIFICATION. left by the said James Knowles at the
Office of the Commissioners of Patents, with his Petition, on the 20th
February 1856.
I, JAMES KNOWLES, of Eagley Bank, near Bolton-le-Moors, in the County
of Lancaster, Coal Proprietor, do hereby declare the nature of the said
Invention for IMPROVEMENTS IN THE CONSTRUCTION OF METALLIC PISTONS, to be
as follows:-
The nature of my Invention consists in placing the packing rings of metallic
pistons each in a separate circular groove formed in the piston block, and in
expanding the packing rings by wedges, which are furnished with shanks
guided in the piston block, and surrounded by coiled springs, the action of
which presses the wedges against the bevilled ends of the packing rings. The
tension of the springs is capable of adjustment by means of lock nuts fitting on
the shanks of the wedges.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Knowles in the Great, Seal Patent Office on the
26th July 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
KNOWLES, of Eagley Bank, near Bolton-le-Moors, in the County of Lancaster,
Coal Proprietor, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of February, in the year of our
Lord One thousand eight hundred and fifty-six, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said James Knowles, Her special license that I, the said James Knowles, my
executors, administrators, and assigns, or such others as I, the said James
Knowles, 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 THE CONSTRUCTION
OF METALLIC PISTONS, upon the condition (amongst others) that I, the said
James Knowles, my executors or administrators, by an instrument 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 James Knowles, do hereby declare. the
nature of my 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 (that is to say):-
The nature of my Invention consists in an improved combination of parts
forming. a metallic piston suitable for the cylinders of steam engines, for
the buckets of air pumps, and for other purposes where metallic pistons are
employed; and in order that my Invention may be fully understood and
readily carried into effect, I will proceed to describe the means pursued by me,
reference being had to the accompanying Drawing, and to the figures and
letters marked thereon.
Fig. 1 is a plan, and Fig. 2 a section, of my improved metallic piston
suitable for the cylinder of a steam engine. a is the body or block of the piston,.
and the lid, which is screwed down in the ordinary manner by the bolts c, c.

page_text: e
The only object of the lid 6 is to prevent the steam entering the piston block.
d, d, are the metallic packing rings, each ring being divided into four segments
at the points and f. Each ring is furnished with two wedges g, cast, forged,
or otherwise attached to the shanks h, the inner ends of which are guided in
holes in the block a. The shanks h are screwed and furnished with screw
nuts i, between which and the boss of the piston blocks are coiled springs j.
These springs abut against the boss of the piston block, and by pressing
against the nuts i cause the wedges g to act upon the bevelled edges of the
packing rings d, d, thereby keeping them in contact with the interior of the
cylinder, and ensuring a steam-tight fit. By turning the screw nuts i so as to
shorten or elongate the coiled springs j, the tension thereof may be increased
or diminished.
Fig. 3 is a plan, and Fig. 4 a section, of an air pump bucket to which my
improvements are applied; as most of the parts in these views are similar to
those above described, they are marked with similar letters of reference. The
packing rings & in this instance are shewn with only one wedge g in each, and
the rings are cut across at one point opposite each wedge, thereby making
each ring into two segments; there may, however, be two wedges to each ring,
if preferred. 1, 1, in Fig. 4, represent the clacks of the air pump bucket,
which are constructed in the ordinary manner. I wish to remark that
although I have shewn the packing rings d, with one or two wedges to each,
I do not limit myself to that number, as in pistons of large dimensions more
may be employed.
Having thus described the nature of my Invention, and the manner of per-
forming the same, I wish it to be distinctly understood that I'make no claim
to any of the parts taken separately, of which my improved pistons are com-
posed, but what I do claim is, the improvements in the construction of metallic
pistons herein-before shewn and described.
In witness whereof, I, the said James Knowles, have hereunto set my
hand and scal, this Twenty-second day of July, in the year of our Lord
One thousand eight hundred and fifty-six.
Witness,
H. B. BARLOW,
Manchester.
JAS KNOWLES. (L.S.)