IMPROVEMENTS IN SPRING SAFETY VALVES
Year: 1873

page_text: LETTERS PATENT to John Spear, of Hull, in the County of York,
Engineer, for the Invention of "IMPROVEMENTS IN SPRING SAFETY
VALVES."
Scaled the 18th November 1873, and dated the 19th May 1873.
PROVISIONAL SPECIFICATION left by the said John Spear at the
Office of the Commissioners of Patents, with his Petition, on the
19th May 1873.
I, JOHN SPEAR, of Hull, in the County of York, Engineer, do hereby
3 declare the nature of the said Invention for "IMPROVEMENTS IN SPRING
SAFETY VALVES," to be as follows:-
This consists essentially in the employment in combination of a
rocking lever and angular adjustable spring.
The object of the said combination is to provide means whereby the
resistance of the spring to the rising of the valve shall be uniform at
every part of the lift, or shall, and this latter I prefer, offer a decreasing

page_text: resistance at every increment of rise of the valve from its seating. The
lever is connected at one end to the valve or its spindle, and it abuts
against or is connected to the spring at its outer end. It moves on a
fulcrum. The spring which is enclosed in a case or guard stands with
relation to the axis of the valve spindle at an angle thereto at all times.
It is free to move on an adjustable joint or bearing at its outer end. It
will be evident that as the valve rises from its seating the angle of the
axis of the spring varies with reference to that of the lever.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Spear in the Great Seal Patent Office
on the 19th November 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
SPEAR, of Hull, in the County of York, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of May, in the year
of our Lord One thousand eight hundred and seventy-three, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said John Spear, Her special
licence that I, the said John Spear, my executors, administrators,
and assigns, or such others as I, the said John Spear, 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
SPRING SAFETY VALVES," upon the condition (amongst others) that I, the
said John Spear, 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 Spear, do hereby declare
the nature of my said Invention, and in what manner the same is to be

page_text: performed, to be particularly described and ascertained in and by the
following statement in writing, reference being had to the accompanying
Sheet of illustrative Drawings, and to the figures and letters marked
thereon, that is to say :—
This consists essentially in the employment in combination of a
rocking lever and angular adjustable spring.
The object of the said combination is to provide means whereby the
resistance of the spring to the rising of the valve shall be uniform at
every part of the lift, or shall, and this latter I prefer, offer a decreasing
resistance at every increment of rise of the valve from its seating.
The lever is connected at one end to the valve or its spindle, and it
abuts against or is connected to the spring at its outer end. It moves
on a fulcrum. The spring, which is enclosed in a case or guard, stands
with relation to the axis of the valve spindle at an angle thereto at
all times. It is free to move on an adjustable joint or bearing at
its outer end. It will be evident that as the valve rises from its
seating the angle of the axis of the spring varies with reference to that
of the lazan

page_text: dotted lines show the position they occupy when the valve is full
open. The angle of the axis of the spring in relation to that of the
lever will determine whether the resistance is practically uniform at
every part of the lift of the valve or whether a decreasing or increasing
resistance is offered.
Fig. 3 is a view in side elevation and section of a safety valve similar
to Figs. 1 and 2, but having an elliptical or so-called coach spring.
Here 9 is the spring and 10 the adjusting nut.
Fig. 4, view in side elevation and section of a safety valve with
helical spring to offer tension resistance; and Fig. 5 an end elevation
of the spring, frame, spindle, and centres. In this modification the
spring 9 is secured at its upper end to the rocking frame 17, having
centres 18 resting in bearings at 18'. The lower end of the spring 9 is
secured to the spindle 19; 20, sleeve passing through frame 17, and
provided with collar for adjusting the tension of the spring 9.
Fig. 6 side elevation and section of a valve similar to Fig. 4, with
spring in tension. Here 9 is the spring shown attached at its upper
end to the cross head 21, supported by the pipe 22. The said pipe 22 is
hinged at 23; 24, spindle to which the lower end
of the spring 9 is
attached. Slots are made in the pipe 22 to allow the attachment to be
made and working and adjustment to take place; 25, adjusting nut.
Fig. 7 is a view similar in all respects to Fig. 6, but with this difference
that the spring is placed above the lever, the spring offering tension
resistance.
The safety valves above described are suitable for either marine or
land purposes, those marked Figs. 1, 2, 3, 4, and 5 being specially suit-
able for marine purposes, and those marked 6 and 7 for either marine or
land purposes.
Although the angles at which the springs stand to the lever may be
varied I prefer those shown on the Drawings.
It will be evident that the lower joint or bearing for the spring,
spindle, or frame might be made moveable, so as thereby to adjust the
resistance of the spring, and that a scale might be made after the
manner of a Salter's balance to indicate the amount of compression or
tension of the spring or springs.

page_text: It will also be evident that the end of the lever may be made to act
on the spring through joints, knife edges, or other mechanical equivalents
instead of through the centres shown.
Further that instead of the fulcrum stud pin centres or knife edges
may be used.
Having now described the nature of my said Invention, and parti-
cularized the same in such manner that others will be enabled to carry
my improvements into effect, I claim as the Invention secured to me by
the herein-before in part recited Letters Patent, the employment in
combination of a rocking lever and angular adjustable spring, substan-
tially in the manner and for the purposes set forth.
In witness whereof, I, the said John Spear, have hereunto set my
hand and seal, the Seventeenth day of November, in the year of
our Lord One thousand eight hundred and seventy-three.
In the presence of Witness,
JAMES STEWART.
JOHN SPEAR. (L.S.)