IMPROVEMENTS IN PISTONS FOR ENGINES DRIVEN BY STEAM OR OTHER ELASTIC FLUID, WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO THE PISTONS OR PLUNGERS OF RECIPROCATING PUMPS
Year: 1855

page_text: LETTERS PATENT in George Mackay Miller. of Inchicore, County of
Place,
Dublin. Civil Engineer. and John Wakefield, of the same
Engineer, for the Invention of "IMPROVEMENTS IN PISTONS FOR ENGINES
DRIVEN BY STEAM OR OTHER ELASTIC FLUID, WHICH IMPROVEMENTS ARE ALSO
APPLICABLE TO THE PISTONS OR PLUNGERS OF RECIPROCATING PUMPS."
PROVISIONAL SPECIFICATION left by the said George Mackay Miller
and John Wakefield at the Office of the Commissioners of Patents.
with their Petition, on the 28th February 1855.
We, GEORGE MACKAY MILLER. of Tuchicore. County of Dublin, Civil
Engineer, & JOHN WAKEFIELD, of the same Place, Engineer, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN PISTONS FOR
ENGINES DRIVEN BY STEAM OR OTHER ELASTIC FLUID. WHICH IMPROVEMENTS ARE
ALSO APPLICABLE TO THE PISTONS OR PLUNGERS OF RECIPROCATING PUMPS," to be as
follow's
Our Invention consists in rendering the piston steam-tight, by causing the
packing thereof to be pressed against the inner surface of the cylinder in.
which it works by the steam dr other elastic fluid or vapour acting upon the
packing from within the piston.
The outer rim of the piston is recessed. in order to receive two separate rings
of packing of any suitable kind. against the inner surface of which the steam or
other elastic fluid or vapour is allowed to act, by its being admitted through
077

page_text: holes at either side of the piston head in such a manner as to come in
immediate contact with the inner surface of the packing or with any suitable
substance inside the packing, thereby making a steam-tight joint between the
outer surface of the packing and the inner surface of the cylinder.
The same arrangement is also applicable to the pistons, plungers. or buckets
of reciprocating pumps.
SPECIFICATION in pursuance of the conditions of the Letters Palent. filed
by the said George Mackay Miller and John Wakefield in the Great
Seal Patent Office on the 27th August. 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, J. GEORGE
MACKAY MILLER. of Inchicore. in the County of Dublin. Civil Engineer, and
JOHN WAKEFIELD, of the same Place. Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria. by Her Lettors
Patent, hearing date the Twenty-eighth day of February, in the year of our
Lord. One thousand eight hundred and fifty-five. in the eighteenth year of
Her reign, did, for Herself. Hor heirs and successors. give and grant unto
us. the said George Mackay Miller and John Wakefield. Her special licence
that we, the said George Mackay Miller and John Wakefield. our executors.
administrators. and assigns, or such others as we. the said George Mackay
Miller and John Wakefield, our executors, administrators, and assigns, should
al 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 "IMPROVE.
MENTS IN PISTONS FOR ENGINES DRIVEN BY STEAM OR OTHER ELASTIC FLUID, WHICH
IMPROVEMENTS ARE ALSO APPLICABLE TO THE PISTONS OR PLUNGERS OF RECIPROCATING
PUMPS," upon the condition (amongst others) that we, the said "Goorge
Mackay Miller and John Wakefield. by an instrument in writing under our
hands and seals, or under the hand and seal of one of us, 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 he filed in the
Great Soal Patent Office within six calendar months next and immediately
after the date of the said Letters Paient.
. NOW KNOW YE, that we, the said George Mackay Miller and John
Wakefield. de hereby declare the nature of our said Invention. and in what
manner the same is to be performed. to be particularly described and ascer-

page_text: tained in and by the following statement, reference being had to the Drawings
hereunto annexed, mind to the letters and figures marked thereon (that is
say):-
.
Our Invention of Improvements in Pistons for. Engines Driven by Sieam
or other Elastic Fluid. which uprovements are also applicable to the Pistons
or Plungers of Reciprocating Pumps," consists in rendering the piston sicam-
Light; by cansing the packing thereof to be pressed against the inner surface of
the cylinder in which it works by the steam or other clastic fluid or vapour
acting upon the packing from within tlic piston.
The outer rim of the piston is recessed, in order to receive two separate rings
of packing of any suitable kind, against. the inner surface of which the steam or
other clastic fluid or vapour is allowed to act, by its being admitted through
holes at either side of the piston head in such a manner as to come in immediate
contact with the inner surface of the packing, or with any suitable substance
inside the packing, thereby making a steam-tight joint between the onter
surface of the packing and the inner surface of the.cylinder.
The same arrangement is also applicable to the pistons, plungers, or buckets
of reciprocating pumps, in which water may also be made to act on the inner
surface of the elastic packing. The position and number of apertures for
admitting the elastic fluid or the water into the interior of the piston head to
the inner side of the packing, also the position and number of the packing rings.
will be varied according to the width of the pistons. The aperinres may also
be formed or arranged either on one side or on both sides of the pistons. piston
valves. piston guages, plungers, or buckets, as each case may require. For
Bylinders fixed vertically. or vertical oscillatory cylinders. the apertures will be
made on both sides of the piston, and as nearly equal as possible in size, so as
in cause an equal or uniform pressure on the inner side of the clastic packing
ring or rings. For cylinders placed at right angles or horizontally, or in an
oblique position, the holes will be made in such a position as to admit à greater
quantity of either water or steam or other elastic fluid or vapour to act on the
lower side of the piston; in order to prevent the weight of the piston from
causing it to rub on the bottom of the cylinder. But we do not confine
ourselves to any particular form, size, or arrangement of the apertures.
In order. however, that our Invention may be fully understood and readily
carried into effect, we will proceed to describe it more particularly by the aid
of the accompanying Drawings. in which are represented different modes of
applying our Invention.
Fig. 1 is a side section of the piston in the line A. B. Fig. 2 is a sectional
plan of the same in the line C. D: Fig. 3 is an edge view; and Fig. 4 a plan

page_text: view of the same. Those Figures represent a piston with inner and other
rings of packing. Fig. 5 is a sectional plan in the line E, F; and Fig. 6 is a
sire section of a piston without the inner rings of packing; Fig. 7 is a sectional
plan in the line G. H, and Fig. 8 is an end section in the line T, K, of a piston
adapted and applied to the use of a slide valve; Fig. 9 is a section through 1
the line N, O. of Figure 10; Fig. 10 is a section in the line P. Q. of
Figure 9. shewing the piston applied to a steam pressure guage: Fig. 11 is an
external clevation. shewing the dial plate. In all these several-Figures the same
letters of reference indicate corresponding parts. r is a piston head: b is the
piston rod; c, the ordinary nut by which the piston is secured to the end of the
rod; d, d, are apertures formed in the piston head, through which the steam or
other clastic fluid is allowed to pass from the interior of the piston to the two
inner olastic packing rings e. c. which cover the joints of the two outer rings
11. which are also covered by a projecting piece g; h is a pin or stop, passing
into the piston hond, by which the packing is prevented from turning round:
i is a groove, extending nearly half way round the piston, to admit. a greater
quantity of steam to equalize the weight. so as to prevent the piston head from
mhhing on the bottom of the cylinder.
The steam or other fluid being admitted to act on one side of the piston hend
is allowed to press upon and expand the rings e and f. in connection with that
side of the piston: as soon as the piston arrives at the end of its course. the
steam or other fluid being exhausted or discharged from the cylinder behind
the piston. the packing rings on that side are released from pressure. The
steam or other fluid being then admitted to the opposite side of the piston, the
packing rings on that side are pressed outwards against the inner surface of
the cylinder, until at the end of the stroke the steam is exhausted or discharged.
when they are relieved from the pressure: in this manner the rings on each
side of the piston are acted upon alternately.
Figs. 5 and 6 represent a piston with only one pair of packing rings, that is,
dispensing with the inner pair. In this case the joints of the outer rings are
covered by means of a tongue or "webb", with a piece * projecting into
the aperture d. The steam or other fluid is admitted through the aperture
in press on the projecting piece o*, and on the inner surface of the "webh" 0
ngainst the inner surface of the packing ring f. thereby maintaining a steam-
tight joint at the opening of the ring on its expansion. The steam or other
fluid is admitted on each side of the piston alternately, and exhausted as
before.
Figures 7 and 8 represent a piston adapted and applied for use as a slide
valve. In this case the onter packing ring is external to the piston, and is of

page_text: greater width than the latter, in order to cover the ports k, k, as required, and the
inner ring a is recessed into the piston head. The steam or other fluid passes
into the piston or slide, and through the apertures d, d, acts upon the elastic
packing rings e and, thereby causing them to expand and accurately cover
the ports as required. The apertures d, d, it will be seen are formed on one
side of the piston head only. I is the inlet for the steam or other fluid; m is
the exhaust pipe; is the cylinder.
Figures 9, 10, and 11 represent a piston applied for use in a pressure guage.
a is the piston head; is an opening or aperture for admitting the steam or
other fluid to net on the packing rings ; is the cylinder.
Having thus described the nature of our Invention, and the manner in which
the same is to be performed. we would have it understood that we do not
intend to confine ourselves to the exact forms or details of the parts shewn and
described, neither do we claim any of the well-known parts to which it has
been necessary to refer in describing our Invention. But what we claim as
of our Invention is, the construction of the piston so that water, steam,
or other elastic fluid can be applied in such a manner as to act or press
on the inner surface of the packing ring or rings, so as to expand the rings
and render the piston steam-tight, if used in a steam cylinder, or in a cylin-
drical steam valve box or pressure guage, or water-tight if used as a pump,
bucket, or plunger, by the pressure of the steam or the water acting upon the
elastic packing within the piston, and thoroby causing the packing to expand
as described, such piston being suited for use with other finids beside stentu
and water.
In witness whereof, we, the said George Mackay Miller and John
Wakefield, have hereunto set our hands and seals, the Twenty-second
day of August, in the year of our Lord One thousand eight hundred
and fifty-five.
GEORGE M. MULLER. (...)
JOHN WAKEFIELD.
Signed, sealed, aid delivered in the presence of
BENJ J. TELFORD,
6, Grantham St., Dublin.
(L.B.)