IMPROVEMENTS IN STEAM ENGINES
Year: 1876

page_text: LETTERS PATENT to Thomas Augustin Grinston, of Clifford, in the County of
York, Flax Spinner, for the Invention of "IMPROVEMENTS IN STEAM ENGINES."
PROVISIONAL SPECIFICATION left by the said Thomas Augustin Grimston
at the Office of the Commissioners of Patents on the 18th May 1870.
THOMAS AUGUSTIN GRIMSTON, of Clifford, in the County of York, Flax Spinner.
"IMPROVEMENTS IN STEAM ENGINES."
My improvements relate to a new form of piston which is built up of three
plates, the front and back cover or plates being perfectly plain, and the centre
plate being bossed on each side. Round each boss studs are planted, each stud
bearing a spiral spring, varied in number and strength as the size of the piston or
pressure of steam may require. These springs bear against a pair of ordinary
piston rings, either once split or in seguents, or against a bearer, which in its turn
abuts on the rings; or the middle plate may be plain and the two outside covers
bossed, studded, and fitted with springs, as above described, the object in either
case being to secure double rings and springs which shall be clear of binding, and
at all times perfectly free to act. The piston rod is attached in the usual manner.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Augustin Grimston in the Great Seal Patent Office on the
18th November 1876.
THOMAS AUGUSTIN GRIMSTON, of Clifford, in the County of York, Flax Spinner.
"IMPROVEMENTS IN STEAM ENGINES."
My improvements relate to a new form of piston to be used in the working
cylinders of steam engines and in the exhaust and supply pumps of the same.
The piston is built up of three plates, the front and back cover or plates being
perfectly plain and the centre plate being bossed on each side. Round each boss
studs are planted, each stud bearing a spiral spring varied in number and strength
as the size of the piston or pressure of steam may require. These springs bear
against a pair of ordinary piston rings either split or in segments or against a bearer,
which in its turn abuts on the rings; or the middle plate may be plain and the two
outside covers bossed, studded, and fitted with springs as above described, the object in
either case being to secure double rings and springs which shall be clear of binding
and at all times perfectly free to act.
And in order that my Invention may be more completely understood, reference is
given to the accompanying Sheet of Drawing and to the letters and marks thereon.
[Price 4d1

page_text: DESCRIPTION OF DRAWING.
Figure 1 is a plan or front elevation of the improved piston with one of its plates
removed to shew more clearly the interior construction thereof, and Figure 2 is a
cross section of the same taken in the line A, B, of Figure 1.
Figures 3 and 4 are respectively a front and transverse section of my improved
piston as adapted to a supply or exhaust pump.
I will now proceed to describe the arrangement of piston shewn at Figures 1
and 2.
The piston consists of three plates a, b, and c. The intermediate plate b being
of somewhat less diameter than the outer plates to provide an annular recess
for the reception of the packing rings. The intermediate plate is provided
on its opposite sides with bosses d, which carry at their periphery any given number
of studs e, each bearing a spiral spring f, which springs vary in strength and
number as the pressure of the steam used in the engine and the size of the piston
require. These springs f bear radially against a pair of piston rings g, which
may be spilt in the ordinary manner or composed of a number of segments, or
the bearers may intervene between the springs fand the rings g, as shewn in the
Drawing.
The bosses d may be either attached to the internal plate b, or to the external
plates a and c, or for the purpose of more readily getting the springs f into position
they may be made separate. When the bosses d are made separate the plates a,
b, and c, are made perfectly plain. I so arrange the parts with regard to each other
in fitting them together that sufficient room is allowed between the plates a, b, and
c, to admit of the free action of the springs fand split rings g. The piston is mounted
on a piston rod i, which is of ordinary construction.
The piston illustrated at Figures 3 and 4 shows the Invention as adapted for use
in the exhaust or supply pumps of steam engines.
This piston is constructed in precisely the same manner as the herein-before
described piston, with the following additions, namely, I perforate the plates a, b, and
c, as shown at ', and set over the plate a an elastic or flexible valve e', which may
be formed of india-rubber or equivalent substance, these perforations are for the
purpose of allowing air or water to pass through the piston when the pump is in
operation. If preferred the boss & may be perforated. The valve e¹ is of ordinary
construction.
Having now set forth the nature of my Invention of "Improvements in Steam
Engines, and explained the manner of carrying the same into effect, I wish it to be
understood that under the above in part recited Letters Patent I claim construct-
ing the pistons of steam engines for receiving metallic packing rings in the manner
and for the purpose above set forth.
In witness whereof, I, the said Thomas Augustin Grimston, have hereunto set
my hand and seal, this Fifteenth day of November, One thousand eight
ludund and soyouty six
Signed, sealed, and delivered by the said
Thomas Augustin Grimston in the pre-
sence of
EDWARD WHITELEY,
Clerk to Mr. Thomas Turner,
Solicitor, Leeds.
T. A. GRIMSTON. (LS.)