IMPROVEMENTS IN THE MANUFACTURE OF PISTON RINGS
Year: 1881

page_text: LETTERS PATENT to Alfred Henshaw, Engineer, of Sheffield, in the County
of York, for an Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
PISTON RINGS,"
PROVISIONAL SPECIFICATION left by the said Alfred Henshaw at the Office
of the Commissioners of Patents on the 14th February 1881.
ALFRED HENSHAW, Engineer, of Sheffield, in the County of York. " IMPROVE-
MENTS IN THE MANUFACTURE OF PISTON RINGS."
My Invention relates to improvements in the manufacture of piston rings, the
object being to produce rings, which, although very similar in appearance to those
at present in use, shall be more correct in principle, more perfect in form, and
which shall require less force to keep them steam tight, and will therefore produce
less frictional resistance.
Ordinary piston rings are usually made and finished of a larger diameter than
that of the cylinder they are intended for, a piece being afterwards cut out of the
periphery to allow the ring to be compressed to suit the size of the cylinder.
It will be obvious that when the ring, originally a true circle, is compressed, it
looses its perfectly circular form, and considerable pressure is required to make it
steam tight.
My Invention consists in making piston rings in the following manner :-
I cast or otherwise form, of any suitable metal, a ring in its first or unfinished
state, of a larger diameter than the size of the engine cylinder, and having a gap
of a suitable size in its periphery; I then close up the gap by a cramp or other
means, and while thus secured I turn up the ring perfectly true and to the exact
size of the inside of the cylinder; thus when the ring is placed in the cylinder it is
a perfect circle, fitting at all the parts of its circumference and consequently steam
tight. Its tendency is to spring open by its own elasticity to its original and
larger diameter, and thus there is no necessity for internal springs. To compensate
for loss of clasticity, which, after a length of time, usually takes place, two lugs
are formed on the inside surface of the ring, one on each side of the gap, and
an adjustable spring placed between them may be made to give the additional
pressure.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alfred Henshaw in the Great Seal. Patent Office on the 13th August
1881.
ALFRED HENSHAW, of Sheffield, in the County of York, Engineer.. "IMPROVE-
MENTS IN THE MANUFACTURE OF PISTON RINGS."
My Invention relates to improvements in the manufacture of piston rings for
engines, pumps, steam hammers, and for other similar purposes, the object of my
Invention being to produce a piston which shall be more correct in principle, more
perfect in form, and which shall require less expansive pressure to keep it steam
tight than ordinary pistons, the rings of which are made on the old plan, and thus
reducing the frictional resistance in the cylinder.
I will here mention that piston rings are usually finished to a larger diameter
than that of the cylinder they are intended to fit, a piece of the ring being cut
out, so that the ring must be compressed to get it in the cylinder, thus it looses
its originally true and circular form and requires considerable pressure to make it
steam tight. My Invention consists in making the rings in the following
manner I cast or otherwise form, of any suitable metal, a ring in its rough
or unfinished state, of a larger diameter than the diameter of the cylinder it is
intended for, with a gap of suitable size in its periphery; this I close by compressing
the ring with a suitable cramp or similar means, and while it is thus compressed
I turn up the ring to the exact diameter of the inside of the cylinder; thus when
the piston is placed in the cylinder the rings are perfectly circular, fitting at all
parts of their circumference, and are consequently steam tight.
Their natural tendency is to spring open to the normal position of the metal
before compression, thus no internal spring is absolutely necessary, but to com-
pensate for loss of clasticity, and as a general auxilliary, I prefer to use in
conjunction with my improved rings, which I recess at the back for that purpose,
a circular hollowed spring, by preference made of steel (the cross section being
crescent shaped), and having a gap to allow of expansion and compression. The
outside of the spring is convex and fits in the recess before described as being
formed in the inside of the rings, and the recess is so shaped that the spring exerts
a vertical pressure as well as an expanding one.
And in order that my Invention may be clearly understood I will now refer to
the annexed Sheet of Drawings, the same letters of reference indicating corre-
sponding parts in all the Figures.
Fig. 1 represents a ring "in the rough" with the gap open, and having two lugs
for the purpose of closing the gap. A is the ring; G is the gap; B, B, are the
lugs. Fig. 2 represents the ring with the gap closed by means of a screw bolt C
passed through the lugs; this is a convenient method, but, as herein before
mentioned, a cramp or other means may be employed to effect this object. Fig. 3
is a cross sectional view of a complete piston made with my improved rings and
spring D.
Fig. 4 represents a sectional and enlarged view of the rings A, A, and the
spring D.
Having now fully described and particularly ascertained the nature of my said
Invention, and the manner in which it may be used or put into practice, I would
observe in conclusion that what I consider to be novel and original, and therefore
claim as the Invention secured to me by the hereinbefore in part recited Letters
Patent is,-
The manufacture and use of piston rings which are turned and finished to the

page_text: size required while compressed or contracted in diameter, so that when placed in
the cylinder they are perfectly circular in form, substantially as hereinbefore
described and illustrated.
In witness whereof, I, the said Alfred Henshaw, have hereunto set my hand
and seal, this Eleventh day of August, in the year of our Lord One thousand
eight hundred and eighty one.
ALFRED HENSHAW, (L.S.)