Improvements in Pistons.
Year: 1889

page_text: Date of Application, 16th Feb., 1889
Complete Specification Left, 18th Nov., 1889-Accepted, 21st Dec., 1889
MUYDUNAT FECIFICATION.
Improvements in Pistons.
We, WALTER GEORGE KENT, of 199, 200 and 201 High Holborn, W.C., in the
County of Middlesex, Manufacturer, and HENRY SAMUEL PRICE, of 124 Kennington
Lane, in the County of Surrey, Engineer, do hereby declare the nature of this
Invention to be as follows:-
Our invention relates to an improved construction of piston, more especially intended
for use in liquid meters, motors, or pumps.
The said piston is formed with a circular disc, or plate fitting the bore of the
cylinder. On each side of the said disc a washer of leather, rubber, or other suitable
elastic material is placed. These washers are so shaped, or moulded, with one or more
suitable corrugations or hollows, around the outer part, that while the central part of
the washer lies flat upon the disc and the extreme edge is also in contact with the
disc, the intervening part is curved away from the disc; a metal plate or washer of
the same form in cross-section as the elastic washers is fitted over each such elastic
washer, and the whole held together by a nut on the end of the piston-rod, or by
means of any other suitable device. Holes are formed in the curved part of each
outer metal disc.
The action of the piston is as follows:-The liquid or other medium under pressure,
being admitted to one side of the piston, will enter the aforesaid holes in the outer
disc, and slightly compress or flatten the curved part of the elastic washer, thus
forcing its periphery into close contact with the cylinder wall, and making a tight
joint. At the end of the stroke, or when the pressure is cut off, the elastic washer
will resume its original form, and the pressure being admitted to the opposite side of
the piston, the same effect will take place on the other washer.
Our improved piston is specially suitable for use in place of the ordinary hydraulic
cup-leather packing, as it will form an equally tight joint with a far less amount of
friction, and consequent loss of power than is experienced in cup-leathers, especially
when working under high pressure, and owing to the small amount of surface in
contact, the liability of the piston to stick in the cylinder is greatly reduced. The
clastic washers will remain tight, and automatically compensate for wear until they
are so far worn that the entire washer is in contact with the central disc. When used
for very heavy pressure, we may place solid or tubular rings or cushions of rubber, or
other suitable elastic material under the curved parts of the washers, to assist their
restoration to form when the pressure is cut off.
In cases where only one side of a piston is subjected to pressure, as in a single
acting pump, an elastic washer on that side of the piston only is employed.
Dated this 15th day of Tshura 1080
AMBROSE MYALL,
21, Cockspur Street, S.W., Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Pistons.
We, WALTER GEORGE KENT, of 199, 200, 201 High Holborn W.C. in the County
of Middlesex Manufacturer and HENRY SAMUEL PRICE of 46 Bonnington Square
in the County of Surrey (but late of 124 Kennington Lane in the County of Surrey)
Engineer do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
Our invention relates to an improved construction of piston, more especially intended

page_text: for use in liquid meters, motors, or pumps, but also suitable for other forms of
apparatus in which pistons are employed.
In the accompanying sheet of drawings Fig. 1 is a sectional elevation and Fig. 2 is
a plan of a piston constructed according to our invention; Figs. 3 and 4 are sectional
elevations of pistons shewing slight modifications in the arrangement of some of
the parts.
Similar letters of reference denote similar parts throughout the drawings.
Referring to Figs. 1 and 2, which represent the piston as constructed more
particularly for use in a water meter, A is a circular disc or plate fitting loosely the
bore of the cylinder B. On each side of the said disc a washer C, formed of leather,
rubber, or other suitable elastic material, is placed. These washers CC are so shaped
or moulded with an annular corrugation or hollow C¹ around the outer part, that while
the central part of the washer lies flat upon the disc A and the extreme edge is also in
contact with the disc, the intervening part is curved away from and out of contact
with the disc. A metal plate or washer D, of the same form in cross-section as the
elastic washers CC, is fitted over each such elastic washer, and the whole held together
by a nut E on the end of the piston-rod F, against a shoulder on the rod. Any other
suitable arrangement may however be employed for securing the parts of the piston
on the rod. Holes H are formed in the curved part of each outer metal disc D.
The action is as follows
The piston is supposed to be moving in the direction indicated by the arrow, through
the medium of the pressure of the fluid on its upper side. The said fluid having
access to the outer surface of the washer C, by means of the holes H in the plate D,
will slightly compress or flatten the curved part (, thus forcing the edge of the
washer outwards into close contact with the cylinder wall, it being unable to escape
downwards being supported by the disc A, and so making a tight joint. When the
piston begins to move under the influence of the pressure, there might under certain
conditions be a tendency for the edge of the washer C to stick to the cylinder wall,
which, permitted, would allow the disc A to move away from it, and a distortion of
the form of the washer would result. The edge of the plate D however, confines the
edge of the washer against the disc A, thus compelling the whole to move together,
and the curved part of the plate ensure the washer retaining its form.
When the
pressure is cut off, at the end or other desired part of the stroke, the washer Cresumes
its original shape, and the pressure being admitted at the end of the stroke to the
underside of the piston, the same effect will take place on the lower washer.
If the piston be supposed to be that of a pump, and moving in the same direction
as before the fluid pressure will be on the underside, being caused by external force
applied to the piston-rod, and in this case it will be the under washer which is
performing the work. There would be no tendency for the under washer to separate
from the disc A, but the upper washer, although not pressed outwards by the fluid,
might have sufficient friction against the cylinder to cause it to leave the disc if not
secured by the plate D. It will thus be seen that these plates D, in combination with
the disc A, perform an important part in the action of the piston.
In the piston shewn in Fig. 3 the central disc A is much thicker. This form of
piston is applicable for force pumps, or steam engines, where the increased pressure
would bend or distort the thin disc shewn in Fig. 1.
In cases where only one side of a piston is subjected to pressure, as in a single-
acting pump, an elastic washer on that side of the piston only, is required, such an
arrangement is shewn in Fig. 4.
Although we have only represented in the drawings pistons formed with a single
annular corrugation or hollow C₁, two or more concentric corrugations may be
employed if desired, the external washers D being shaped to correspond therewith,
and when the pistons are used for very heavy pressure, we may place rings or cushions
of rubber or other suitable elastic material, under the curved parts C of the washers,
to assist their restoration to form when the pressure is removed.
Rings of various patterns may be employed, thus in Fig. 3 a ring J having a curved
upper surface, with ribs on the under side, is shewn applied to the top washer C, while

page_text: a solid ring K is shewn for the bottom washer. In Fig. 4 a tubular ring L is
shewn.
Our improved piston is specially suitable for use in place of the ordinary hydraulic
cup-leather packing, as it will form an equally tight joint with a far less amount of
friction and consequent loss of power than is experienced in cup-leathers, especially
when working under high pressure and owing to the small amount of surface in
contact with the cylinder walls the liability of the piston to stick is greatly reduced.
The elastic washers will remain tight and automatically compensate for wear until they
are so far worn that the entire washer lies flat and in contact with the disc A.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is :-
1. A piston wherein the packing consists of one or more corrugated elastic washers C,
in combination with a disc A and external plates D, the said washers being extended
by the pressure of the fluid in the cylinder and thus forming a tight joint against the
cylinder walls, substantially as herein set forth.
2. A piston having elastic washers C as set forth in the preceeding claim in com-
bination with elastic rings J, K or L, substantially as and for the purposes herein set
forth.
3. A piston constructed substantially as and for the purposes herein set forth with
reference to Figs. 1 and 2 of the accompanying drawings.
4. A piston constructed substantially as and for the purposes herein set forth with
reference to Fig. 3 of the accompanying drawings.
"
5. A piston constructed substantially as and for the purposes herein set forth
with reference to Fig. 4 of the accompanying drawings.
Dated this 16th day of November 1889.
AMBROSE MYALL,
21, Cockspur Street, London, S.W., Agent for the Applicants.