IMPROVEMENTS IN SPRING SAFETY VALVES
Year: 1874

page_text: LETTERS PATENT to William Caldwell, of Manhattan Villa, Summer-
side Placo, Leith, Scotland, for the Invention of "IMPROVEMENTS IN
SPRING SAFETY VALVES."
Sealed the 2nd April 1875, and dated the 23rd December 1874.
PROVISIONAL SPECIFICATION left by the said William Caldwell at
the Office of the Commissioners of Patents, with his Petition, on
the 23rd December 1874.
Ì, WILLIAM CALDWELL, of Manhattan Villa, Summerside Place,
Leith, Scotland, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN SPRING SAFETY VALVES," to be as follows:-
This Invention has for its object improvements in the construction of
gear in connection with spring-loaded safety valves to allow of the
spring being released, whether pressure is on safety valve or not, and to
resume its original length if needs be.
The improvements relate to improved means of putting the pressure
upon the spring, and of adjusting the pressure which can be put upon

page_text: In order that my improvements may be properly understood, I have
shown in the Drawings hereto annexed two examples of spring safety
valves with my improvements applied to them.
Figures 1, 2, 3, and 4, shew one arrangement of spring safety valvo
and gear. Figure 1 represents a sectional clevation of spring chest
through B, C, and Figure 2 is an outside elevation of spring chest
showing levors, &c., through D, E. Figure 3 is a plan of pinion and
geared rest used to regulate compression of spring. Figure 4 is a plan
of chest shewing levers, &c., for releasing and compressing spring.
Figure 5 is an elevational section showing a modified arrangement for
releasing and compressing the spring.
In Figures 1, 2, 3, and 4, A, A, is a locked pinion and geared rest for
regulating compression of spring; G is the spiral spring for loading
valve; H is a rubber casing for preventing escape of steam into spring
chest; I is a brass tube with studs J, K, cast on for attachment to :
levers L, M, for releasing and compressing spring; N is a cross for
turning valvo with spindle round on seat should any dirt get between
faces; O is the spring casing; P is the cover of spring casing with
locking arrangement of adjusting pinion; R is the spindle attached to
safety valvo; S is a flange for attachment to safety valve chamber and
padlock through one bolt for locking; T is a rod to wheel gear in engino
room for releasing and compressing spring.
It will be seen that the spring cannot be compressed more than is
permitted originally by the locked arrangement above explained.
In the modified arrangement, shown at Figure 5, the tube I has a g
screw thread cut around it and it screws into a bush in the top of the
spring casing O. On the tube I is a toothed wheel W into which goars
a pinion X by which the tube I may be turned to release or compress
tho spring. In other respects the arrangement is the same as that shewn
at Figures 1, 2, 3, and 1.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Caldwell in the Great Seal Patent Office.
on the 23rd June 1875.
on the 23rd June 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
CALDWELL, of Manhattan Villa, Summerside Place, Leith, Scotland,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent bearing date the Twenty-third day of December, in the year of our
Lord One thousand cight hundred and seventy-four, in the thirty-eighth
> year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Caldwell, Her special license
that I, the said William Caldwell, my executors, administrators, and
assigns, or such others as I, the said William Caldwell, 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 William Caldwell, 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 monthis next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said William Caldwell, 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 the construction of
11

page_text: The improvements relate to improved means of putting the pressure
upon the spring, and of adjusting the pressure which can be put upon
the valve.
In order that my improvements may be properly understood, I havo
shown in the Drawings hereto annexed two examples of spring safety
valves with my improvements applied to them.
Figures 1, 2, 3, and 4, show one arrangement of spring safety valve
and gear. Figure 1 represents a sectional elevation of the spring chest.
This section is taken through the line B, C, (Figure 4). Figure 2 is an
outside clovation of the spring chest shewing levers and other parts.
Figure 3 is a plan of the pinion and geared rest used to regulate the
compression of the spring. Figure 4 is a plan partly in section of the
chest showing levers and other parts for releasing and compressing
the spring.
Figure 5 is an elevational section shewing a modified arrangement for:
releasing and compressing the spring.
In Figures 1, 2, 3, and 4, A, A, is a locked pinion and geared rest for
regulating the compression of the spring; G is the spiral spring for
loading the valve; H is a rubber casing for preventing the escape of
steam into the spring chest; I is a brass tube with studs J, K, cast on
for attachment to levers L, M, for releasing and compressing the spring;
N is a cross or hand wheel for turning the valve with its spindle round
on the seat should any dirt get between the faces; O is the spring
casing P is the cover of spring casing with the locking arrange-
ment of the adjusting pinion; R is the spindle attached to the safety
valvo; S is a flange for attachment to the safety valvo chamber and
padlock through one bolt for locking; T is a rod passing to wheel
gear in the engine room for releasing and compressing the spring.
It will be seen that the spring cannot be compressed more than is
permitted originally by the locked arrangement above explained.
3
☐ In the modified arrangement, shewn at Figure 5, tho tube I has a
screw thread cut around it, and it screws into a bush in the top of the
spring casing O. On the tube I is a toothed wheel W into which gears
a pinion X, by which the tube I may be turned to release or compress
the spring. In other respects the arrangement is the samo as that shewn
at Figures 1, 2, 3, and 4.

page_text: Having thus described my Invention and the manner in which the
same is to be performed, I would remark that I do not restrict myself
to the precise details herein described and shown; but what I claim is,
the construction of direct-loaded spring safety valves for marine or land
purposes, with gear for releasing the spring in compression, and for con-
trolling the pressure applied to it, substantially as described.
In witness whereof, I, the said William Caldwell, have here-
unto set my hand and scal, this Twenty-first day of June, in the
year of our Lord One thousand eight hundred and seventy-
fivo.