IMPROVEMENTS IN METALLIC PISTONS
Year: 1878

page_text: LETTERS PATENT to Thomas Joseph Perry, of Highfields Works, Bilston, in the
County of Stafford, Engineer, for the Invention of "IMPROVEMENTS IN
METALLIC PISTONS."
Sealed the 15th November 1878, and dated the 17th May 1878.
PROVISIONAL SPECIFICATION left by the said Thomas Joseph Perry at the
Office of the Commissioners of Patents on the 17th May 1878.
THOMAS JOSEPH PERRY, of Highfields Works, Bilston, in the County of Stafford,
Engineer. "IMPROVEMENTS IN METALLIC PISTONS."
My Invention relates to metallic pistons, and consists in an improved method of
forcing the metallic packing rings of the piston against the interior of the cylinder
in which the piston works.
I prefer to use two metallic packing rings, which are suitably turned internally,
and which have within them a third ring of a vee or wedged shaped section, by
virtue of which the outward pressure of the said vee-shaped ring tends not only to
press the packing rings against the cylinder, but also to separate the packing rings
from each other, and to keep them in close contact with the flat surfaces of the
piston body and of the piston cover respectively.
My Invention relates particularly to the means whereby an adjustable outward
pressure to the said vee-shaped ring is given, and is performed in the following
manner: Around the circumference of the piston body and well within the interior
of the vee-shaped ring is arranged, radially, a suitable number of bolts or screws,
the heads of which bolts or screws point in an outward direction, and have attached
to each of them a single blade spring, which is bent so that its extremities rest
against the interior of the said vee-shaped ring. Each of the said bolts is provided
0
Price G1

page_text: with a nut, shaped externally to fit any suitable spanner, and each nut is placed
within a recess in the piston body in such a manner that when the said nut is
turned upon its bolt the latter is projected or withdrawn, and the pressure of
the blade spring upon the vee-shaped ring is thereby increased or diminished at
pleasure.
By preference each bolt has a square head, and the blade spring is attached thereto
by being passed through a rectangular slot cut transversely through the said head.
The part of the shank which adjoins the head may also be made square in its
transverse section, so that when passed through a square hole in the side of the
aforesaid recess in which the nut is situated the bolt is prevented from turning
round with the nut.
In order to give access for the adjustment of the said nute, without the necessity
of removing the junk ring or cover of the piston, I form in and through the said
junk ring or cover, and opposite cach nut, an opening large enough for the intro-
duction and working of a suitable spanner for turning the said nut; and after the
adjustment has been made I close each opening by means of a small door carefully
fitted thereto, and secured by bolts or screws, so as to excludo the steam or other
fluid from the interior of the piston.
*SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Joseph Perry in the Great Seal Patent Office on the 15th 2
November 1878.
THOMAS JOSEPH PERRY, of Highfields Works, Bilston, in the County of Stafford,
Engineer. "IMPROVEMENTS IN METALLIC PISTONS."
My Invention relates to metallic pistons, and consists in an improved method of
forcing the metallic packing rings of the piston against the interior of the cylinder 2
in which the piston works.
I prefer to use two inetallic packing rings, which are suitably turned internally,
and which have within them a third ring of a vee or wedge-shaped section, by
virtue of which the outward pressure of the said vec-shaped ring tends not only to
press the packing rings against the cylinder, but also to separate the packing rings
from each other, and to keep them in close contact with the flat surfaces of the
piston body and of the piston cover respectively.
My Invention relates particularly to the means whereby an adjustable outward
pressure to the said vee-shaped ring is given, and is performed in the following
manner-Around the circumference of the piston body and well within the interior
of the vee-shaped ring is arranged, radially, a suitable number of bolts or screws,
the heads of which bolts or screws point in an outward direction, and have attached

page_text: to each of them a single blade spring, which is bent so that its extremities rest
against the interior of the said vec-shaped ring. Each of the said bolts is provided
with a nut shaped externally to fit any suitable spanner, and each nut is placed
within a recess in the piston body in such a manner that when the said nut is
turned round upon its bolt the latter is projected or withdrawn, and the pressure
of the blade spring upon the vee-shaped ring is thereby increased or diminished at
pleasure..
By preference each bolt has a square head, and the blade spring is attached thereto
by being passed through a rectangular slot cut transversely through the said head.
The part of the shank which adjoins the head may also be made square in its
transverse section, so that when passed through a square hole in the side of the
aforesaid recess in which the nut is situated the bolt is prevented from turning
round with the nut.
In order to give access for the adjustment of the said nuts, without the necessity
of removing the junk ring or cover of the piston, I form in and through the said
junk ring or cover, and opposite each nut, an opening large enough for the intro-
duction and working of a suitable spanner for turning the said nut; and after the
adjustment has been made I close each opening by means of a small door carefully
fitted thereto, and secured by bolts or screws, so as to exclude the steam or other
fluid from the interior of the piston.
That my Invention may be fully understood I have annexed Drawings thereof,
which I now proceed to describe :---
Fig. 1 is a half elevation and half section; and Fig. 2 is a half plan and half
sectional plan of a piston constructed according to my Invention.
Similar letters of reference refer to like parts in both Figures.
A is the piston body, and B is the junk ring or cover secured to the body A by
means of the screws C, C; D, D, are two packing rings having their inner and
meeting edges bevelled, as shewn, and fitted with a vee-shaped ring E; F, F, are bolts,
the number of which depends upon the size of the piston, and having heads G, G,
through which are passed blade springs H, H. The necks I, I, of the said bolts are
made square, and fit easily in square holes in the circular rib K of the piston. The
stems F, F, of the said bolts are screwed and pass easily through holes in the inner
rib M of the piston. Between the said ribs K and M, and screwed upon the
bolts F, F, are nuts N, N, the exterior form of which may be varied to suit any
required form of spanner. Those shewn in the Drawing have capstan heads with
recesses around their circumference into which the projecting end of a capstan
spanner may engage.
When the said nuts are turned to the right or to the left the bolts F, F, are
withdrawn from or projected towards the outer circumference of the piston, and the
springs H, H, being thereby released or compressed the pressure of the vee-shaped
ring E tending to expand the packing rings D, D, both against the inside of the
cylinder, and against the flat surfaces of the piston and its cover may be adjusted
to the required degree.
In order that the adjustment of the nuts N, N, may be effected without removing
the cover or junk ring B, I provide an opening P over each nut, and I close each
said opening against the entrance of the steam or other fluid by means of a cover R
secured by screws S, S.
Having now described the nature of my Invention, and the manner in which the
same may be carried into effect, I desire it to be understood that I do not limit
myself to the precise details herein-before described, and illustrated in the accom-
panying Drawings, as the same may be varied or modified to some extent without
departing from the nature of my said Invention, but what I do claim as the
Invention to be protected by the herein-before in part recited Letters Patent is, the
use of single blade springs in metallic pistons in combination with radial bolts and
nuts for expanding a vee-shaped ring against the internal surfaces of the packing

page_text: rings of the said metallic piston, substantially as herein-before described, and
illustrated in the accompanying Drawings.
In witness whereof, I, the said Thomas Joseph Perry, have hereunto set my
hand and seal, this Fourteenth day of November, in the year of our Lord
One thousand eight hundred and seventy-eight.
ROARTE
THOMAS J. PERRY. (LS.)