CERTAIN IMPROVEMENTS IN, STEAM ENGINES
Year: 1857

page_text: LETTERS PATENT to George Gimson, of Staley Bridge, in the County of
Lancaster, Engineer, for the Invention of "CERTAIN IMPROVEMENTS IN,
STEAM ENGINES."
Sealed the 7th August 1857, and dated the 12th February 1857.
PROVISIONAL SPECIFICATION left by the said George Gimson at the
Office of the Commissioners of Patents, with his Petition; on: the
12th February 1857.
I, GEORGE GIMSON, of Staley Bridge, in the County of Lancaster, Engineer,
do hereby declare the nature of my said Invention for "CERTAIN IMPROVEMENTS
IN STEAM ENGINES," to be as follows:-
My Invention relates to the slide valves of steam engines, and consists
principally in the novel form and description of the valve and its seating, which
is designed for the purposes of decreasing the amount of friction upon the valve
seating, and also of lessening or equalizing the pressure of steam upon the
back of the valve; and consequently upon the said seating. These objects are
attained by making both the seating and valve or covering for the steam
'ports" of a circular form, the surface of the valve being only made
sufficiently wide to cover the "ports" when closed. The circular valve opens
5 and closes the "ports" by an alternate rocking or reciprocating motion upon
its axis, which is imparted to the valve from the main driving shaft of the

page_text: engine. The back of the valve is also circular in form, so that the steam may
exert an equal pressure upon all sides of the said valve, and thereby cause a
more efficient action of the engine.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Gimson in the Great Seal Patent Office on the
12th August 1857.
.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
GIMSON, of Staley Bridge, in the County of Lancaster, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of February, in the year of our Lord
One thousand eight hundred and fifty-seven, in the twentieth year of Her
reign, did, for. Herself, Her heirs and successors, give and grant unto me, tho
said George Gimson, Her especial license that I, the said George Gimson, my
executors, administrators, and assigns, or such others as I, the said George
Gimson, my executors, administrators, and assigns, should at 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 "CERTAIN IMPROVEMENTS IN STEAM
ENGINES," upon the condition, amongst others, that I, the said George
Gimson, by an instrument in writing under my hand and seal, should par-
ticularly describe and ascertain the nature of my said Invention, and in
what manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said George Gimson, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement and accompanying Drawings, that is to say :--
My Invention relates to the slide valves of steam engines, and consists
principally in the novel form and description of the valve and its seating and
spindle, which is designed for 'the purposes of decreasing the amount of friction
upon the valve seating, and also of lessening or equalizing the pressure of
steam upon the back of the valve, and consequently upon the said seating.
These objects are attained by making both the seating and the face of the

page_text: valve or covering for the steam "ports" of a circular form, that is, partaking
of the form of half or any desired segment of a circle, and the valve spindle or
axle covering a certain portion of the back of the valve and working on the
centro of such circle or cylinder. The circularly-formed valve opens and closes
the "ports" by an alternate rocking or reciprocating motion upon its axis;
which is imparted to the valve through the valve spindle from the main
driving shaft of the engine by means of any of the well-known "valve
motions." The back of the válve is also made in a circular form, so that the
steam may exert an equal pressure upon all sides of the said valve, and 'thereby
effect the more even and perfect action of the engine.
In order that this Invention may be more clearly understood, I have here-
unto annexed a Sheet of Drawings, illustrative of the valve and its application
to the steam engine, having similar letters of reference marked upon cor-
responding parts of the mechanism throughout all the Figures exhibited.
Fig. 1 is a sectional elevation of the steam cylinder of an engine, shewing
the application of the improved steam valve thereto (also shewn in section);
Fig. 2 is a plan or horizontal view of the same, shewn in section; Fig. 8 is a
detached view of the steam valve, shewing the circularly-formed back and
recess in the valve spindle or axle in which the circular-shaped back of the
valve is secured; this Figure also shews the method of applying an internal
spring to be employed as an elastic packing to keep the valve against its
seating. Figs. 4, 5, 6, are respectively detached views of the valve spindle and
packing, and the face and back of the valve.
In Fig. 1, a, a, is the steam cylinder; and b, b, the steam "ports," through
which steam is admitted to the cylinder by means of the cylindrical or circular
valve c, which moves upon the corresponding circular face of the valve seating
d; E is the valve spindle, by means of which a reciprocating or rocking motion
is imparted to the valve, actuated by any ordinary valve gear or motion, and
upon which is secured the valve box or recess f, which has its exterior surface
rounded or partly circular in form, in order to equalize the pressure of steam
on all sides thereof; this box or recess f covers the valve, so that the steam
cannot get to the back of the valve or portion so covered.
In Fig 3, 9 is an adjusting screw, passing through the back of the
valve, for the purpose of regulating the pressure of the spring upon the
packing and valve, which may be employed as an elastic medium, as
shewn in this Figure (if preferred), or a solid packing, such as india-
rubber or other clastic substance possessing sufficient elasticity for the
working of the valve, but still so packed as to prevent steam from escaping
and getting behind it, as in Fig. 2. It will be evident that by rounding or

page_text: curving the opposing surfaces of the valve c and its seating d, and also,
similarly shaping or forming the back of the valve f, more even pressure will
be exerted upon the valve, and less friction will exist between the opposing.
sliding surfaces of the slide valve and its seating, as the packing of the valve.
prevents steam from passing into or, behind the valve and exerting pressure 5
thereupon, so that the face of the valve is relieved of the pressure against its.
seating in proportion to the area of the back of the valve, a considerable.
portion of the pressure of the steam upon the outer case fand other uncovered.
parts being sustained by..the valve spindle and its bearings.
Having now described the nature of my said Invention, together with the
manner of carrying the same into practical effect, I wish it to be distinctly
understood that I claim as of my Invention the novel form or construction of.
the face of the slide valve and its seating, and valve spindle or axle, covering a
considerable portion of the surface of the back of the valve, and sustained or
working on its centre, thereby relieving the face of the valve of the pressure of
so much of the surface so covered in conjunction with the elastic-packing.of.
the valve, and the application, employment, or use of the same in steam
engines; also the rounded or circularly-formed back of such slide valve,
together.with the general arrangement and construction of the parts of the
same, as herein-before described, set forth, and fully exhibited and detailed in
the Drawings annexed.
In witness whereof, I, the said George Gimson, have hereunto set my
hand and, seal, this Eleventh day of August, in the year of our Lord
One thousand eight hundred and fifty-seven.