IMPROVEMENTS IN SAFETY VALVES
Year: 1866

page_text: LETTERS PATENT to John Russell Swann, of Windsor Cottage, Mont-
gomery Street, Edinburgh, for the Invention of "IMPROVEMENTS IN SAFETY
VALVES."
Sealed the 18th December 1866, and dated the 3rd October 1866.
PROVISIONAL SPECIFICATION left by the said John Russell Swann at
the Office of the Commissioners of Patents, with his Petition, on the
3rd October 1866.
I, JOHN RUSSELL SWANN, of Windsor Cottage, Montgomery Street, Edin-
burgh, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN SAFETY VALVES," to be as follows:-
This Invention has for its object improvements in safety valves. Very many
accidents to steam boilers at present occur in consequence simply of an undue
weight being applied to the lover of the safety valve. Now according to my
Invention I so arrange the apparatus that an undue weight applied to the
lever of the valve, in place of allowing an increase of pressure in the boiler,
will cause the steam to blow off at any pressure to which the apparatus may
be set. In place of arranging the valve lever to turn on a fixed centre or axis,
as is usual, I arrange the centre or axis in such manner that it is kept down
only by a spring or weight which yeilds when undue pressure is applied at
the other end of the lever; the outer arm of the lever then descends a short
distance till it comes against a fulcrum arranged for it between the valve and the
weight, and then the undue weight applied to the lever aids in taking pressure

page_text: from the valve. The inner end of the lever with its centre or axis is cased in
so that it cannot be tampered with. The same arrangement is applicable
where an adjustable spring is applied to the outer end of the valve rod in place
of a sliding weight.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Russell Swann in the Great Seal Patent Office on
the 3rd April 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOON
RUSSELL SWANN, of Windsor Cottage, Montgomery Street, Edinburgh, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Third day of October, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Russell Swann, Her special licence that I, the said John
Russell Swann, my executors, administrators, and assigns, or such others as
I, the said John Russell Swann, 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 "IMPROVEMENTS IN SAFETY VALVES," upon the condition (amongst others)
that I, the said John Russell Swann, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and seals,
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 be filed in the Great Seal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Russell Swann, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
This Invention has for its object improvements in safety vales. Very many
accidents to steam boilers at present occur in consequence simply of an undue
weight being applied to the lever of the safety valve. Now according to my
Invention I so arrange the apparatus that an undue weight applied to the

page_text: may not be tampered with; m is a screw plug which closes the recess in the
casting a in which the spiral spring is contained:
Invention
In connection with safety valves arranged according to my
apparatus may conveniently be applied to indicate when the water in the
boiler is deficient by causing the steam to escape from the valve. Figure 4
shows, partly in section, apparatus for this purpose; n is a bushing screwed
into the top of the boiler, and o is a plug passing freely through it; a valve o'
is formed at its lower end, and this resting against a face at the lower end of
the bushing prevents any escape of steam; p is a spiral spring which tends
constantly to draw the valve o' up to its seat; q is a chain connecting the upper
end of the plug o with the outer end of the weight lever d of the valve; r
represents a heavy float connected by a chain with the lower end of the plug o
and which should rest on the surface of the water in the boiler, when, however,
the water falls too low this float being unsupported its weight draws down the
plug o, and by the chain q the weight of the float is transmitted to the lever d,
and this additional weight causes the pressure on the safety valve to be relieved,
as already explained.
What I claim is the arranging the parts of a safety valve as herein-before
described, and especially the combined application to safety valves of a yielding
fulcrum for the valve lever, and a stud or stop to receive and support the valve
lever as soon as the fulcrum commences to yield.
In witness whereof, I, the said John Russell Swann, have hereunto set
my hand and seal, this Twenty-second day of March, in the year of
our Lord One thousand eight hundred and sixty-seven.
J. R. SWANN. (L.S.)