IMPROVEMENTS IN STEAM ENGINES AND IN PUMPS
Year: 1850

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
Mills, of Bow, in the county of Middlesex, Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-second day
of July, (One thousand eight hundred and fifty,) in the fourteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the said
Thomas Mills, my exors, adññors, and assigns, Her especial licence, full power,
sole privilege and authority, that I, the said Thomas Mills, my exors, adiñiors,
and assigns, or such others as I, the said Thomas Mills, my exors, adñiors, or
assigns, should. at any time agree with, and no others, from time to time and
at all times during the term of years therein expressed, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town
of Berwick-upon-Tweed, my Invention of "IMPROVEMENTS IN STEAM ENGINES
AND IN PUMPS;" in which said Letters Patent is contained a proviso that
I, the said Thomas Mills, shall cause a particular description of the nature of
my said Invention, and in what manner the same is to be performed, by an
instrument in writing under my band and seal, to be inrolled in Her Majesty's
High Court of Chancery within six calendar months next and immediately
after the date of the said in part recited Letters Patent, as in and by the same,
reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Thomas Mills, hereby declare that the nature of my said Invention, and the

page_text: manner in which the same is to be performed, are fully described and ascer-
tained in and by the present Specification thereof, reference being had to the
Drawings hereunto annexed, that is to say :-
My Invention, in so far as regards improvements in steam engines and
pumps, consists in an improved method of causing the packing of the piston of
the plunger to fit to any inequality there may be in the diameter of the steam
cylinder or pump barrel, which method affords at the same time great facilitics
for encreasing the expanding pressure of the packing of the piston or pump
bucket during any temporary stoppage of the engine or pump, and without
having the trouble of taking the piston or bucket out of their places. Figures 1
to 14 inclusive exhibit exemplifications of these improvements applied to the
piston of a steam engine. Figure 1 is a plan of a piston with my improved
packing. Figure 2. a plan with the junk ring removed. Figure 8, a vertical
section; and Figure 4 an elevation partly in section, of one variety of this
piston. The body A of the piston and junk ring B are nearly similar to those of
the common pistons now in usc. C, C, are the packing rings and D an inner ring
which is nearly of the same depth as the two packing rings, and is turned or
otherwise finished so as to bear uniformly with its exterior surface upon the
inner surfaces of the packing rings. The ring D has an angular portion cut
out of it as represented in the plan and clevation given separately in Figures 5
and 6, into which angular space there is fitted a welge E, by which the ring
is made to expand to the extent sufficient to cause it to bear against the
packing rings. Figure 7 is an elevation, Figure 8 an edge view, and
Figure 9 a plan of the wedge piece E. F is a cavity formed in the wedge E
which serves for the reception of a nut G and spiral spring H, which is
superimposed between the nut and the wedge E. The spiral spring H exerts
a constant upward pressure upon the wedge, and this pressure can be encreased
to any desired extent, without undoing the piston or even having to remove it
from the cylinder, by simply turning the screw I so as to compress the spring.
The screw I passes through the junk ring and terminates in a rose-formed
head. K is a spring catch which is fixed to the junk ring, and by taking into
the notches of the rose head prevents the screw from turning round. The
wedge-shaped piece might be used without the spiral spring, but not so
advantageously. When pistons of this improved construction are employed in
horizontal and oscillating steam engine cylinders, then the back of the wedge-
shaped piece should be bevilled, as shown at a, a, in Figure 7, and the recess
in the piston into which the wedge-shaped piece is fitted should have a
corresponding bevil cut upon it, so that as the wedge is pressed upwards (in
course of the wear of the parts), these two bevilled surfaces may still keep in

page_text: contact, and thus give firmness to the piston; the advantage of this arrange-
ment will be more especially experienced when the wedge is put at the lower
side of the piston in horizontal cylinders. In oscillating cylinders the wedge
is most beneficially placed on that side of the piston immediately opposite to
the throw of the crank after it has passed the top of the stroke. Figure 10 is
a cross section, and Figure 11 an elevation partly in section, of another steam
engine piston, with a somewhat different arrangement for causing the packing
to expand. Figure 12 is a plan of the packing and expanding rings separate
from the piston. Figure 13 is an elevation of the expanding ring, which is
composed of a thin band or hoop of steel A, upon which there are fitted
several bearing pieces B, B, which press upon the packing rings.. The stecl
band A acts as a spring, which yields in the event of the diameter of the
cylinder requiring a corresponding expansion or contraction of the piston to
take place during the act of making a stroke, so that the wedge-shaped picco
in this case requires no helical spring. Figure 14 is a horizontal section of
another modification. A, A, is the body of the piston. B, B, the packing
rings. C, C, the ring which is expanded by means of a wedge-shaped piece
similar to that before described. D, D, D, are springs which are interposed
between the packing rings B, B, and the ring C. Figure 15 represents the
section of a cylinder and cover containing a piston; a in the cover shews an
orifice through which a key L may be introduced for the purpose of turning
the screw I,, whereby the spiral spring may be made to act upon the wedge
piece. By this means it is considered that the piston may be adjusted at any
time with a delay of only a few minutes working. The orifice a to be stopped
by means of a screw. Figure 16 is an elevation and Figure 17 a plan of a
pump bucket constructed upon a similar principle to the pistons before
described. A, A, is an expanding ring and B a wedge piece as before. C is
a screw by which the wedge is made to cause the ring A to expand. This
bucket is constructed for being fitted with a hempen packing, upon which the
expanding ring A may act instead of acting upon a metallic packing.
D, D, are two ledges or collars which are bevilled upon their inner edges, as
indicated by the dotted lines a, a, b, b, so as to cause the hempen packing as it
is made to expand to become more compact upon the outer surface where it
comes in contact with the pump barrel.
And having now described my said Invention, and the manner in which the
same is to be performed, I declare that which I claim is as follows:-
First, I claim the constructing of pistons for steam engines and pumps, with
an expanding ring acted upon by a wedge-shaped piece acting parallel to the