IMPROVEMENTS IN SAFETY VALUED
Year: 1874

page_text: LETTERS PATENT to Samuel Wilkinson Snowden, of No. 3, Downs
Crescent, Amherst Road, Stoke Newington, in the County of
Middlesex for the Invention of "IMPROVEMENTS IN SAFETY VALUED "
Middlesex, for the Invention of "IMPROVEMENTS IN SAFETY VALUES"
Sealed the 24th November 1874, and dated the 2nd June 1874.
PROVISIONAL SPECIFICATION left by the said Samuel Wilkinson
Snowden at the Office of the Commissioners of Patents, with his
Petition, on the 2nd June 1874.
I, SAMUEL WILKINSON SNOWDEN, of No. 3, Downs Crescent, Amherst
Road, Stoke Newington, in the County of Middlesex, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN SAFETY VALVES," to
be as follows:-
-
The object of this Invention is to apply a spring to load the valve or
press it towards its seat, in such a manner as in case of the fracture of
the spring to avoid the inconvenience and risk from loss of steam, which
in the case of marine valves (especially those which are locked up so as
to be beyond to control of the engineer) is a matter of scrious
importance. I apply the spring to one-end of a lever capable of turning

page_text: on a fixed fulcrum, and the other end of the lever presses upon the stem
of the valve. There is also another similar lever placed above the valve
lever and the spring connects one lever with the other drawing the
extremity (to which it is attached) of the lower or valve lever upwards,
and that of the upper lever downwards. The action of the spring on
the upper lever is nearly counterbalanced by a weight hung from its
other end, but the weight being just overpowered by the spring is lifted
until it rests against a fixed stop. It is the tension spring alone which
holds the valve to its seat so long as this spring remains in working
order, but when it breaks it lets fall the weight which then bears upon
the valve, and so after the breaking of the spring the valve remains
loaded to an extent but slightly inferior to the original load which the
spring when in working order applied.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Samuel Wilkinson Snowden in the Great Scal
Patent Office on the 2nd December 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, SAMUEL
WILKINSON SNOWDEN, of No. 3, Downs Crescent, Amherst Road, Stoke
Newington, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 1
Letters Patent, bearing date the Second day of June, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Samuel Wilkinson Snowden, Her special
license that I, the said Samuel Wilkinson Snowden, my executors, ad-
ministrators, and assigns, or such others as I, the said Samuel Wilkinson
Snowden, my executors, administrators, and assigns, should at any timo
agree with, and no others, from time to time and at all times thercafter
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 Samuel Wilkinson Snowden, my executors or adminis-
trators, by an instrument in writing under my, or their, or one of

page_text: Figure 1 is an elevation; and Figure 2 is a plan both partly in section
of a safety valve constructed and arranged according to my Invention.
Figure 3 is a longitudinal section of the same.
a, a, is the case of the apparatus, it contains a pair of valves; b, b, are
the valves; and c, c, brass seatings fitted for them in the lower part of
the case which is properly secured to the boiler or steam chamber in
connection therewith. dis the outlet for the steam when it has passed
the valves; e, e, are rods stepped at their lower ends into sockets on the
tops of the valves; and f, f, are the springs, which when intact draw
downwards the ends of levers g, g, having their fulcra at g', g¹, and so
by causing the levers to press on the heads of the rods e, e, the springs
load the valves to the extent desired. The tension of the spring f, f, is
adjusted by screws and nuts in the ordinary manner. The lower ends
of the rods e, e, and the sockets on the valves into which they are
received are square in form, and the valves can be turned round in their
seats, when desired, by means of the small hand wheels e', e¹, on the
heads of the rods e, e. The lower ends of the springs f, f; are not

page_text: .
attached to fixed points as would be usual, but they are secured to the
ends of levers h, h, having fulcra at h³, . The levers are forked and
abut upon nuts 1, 2, on the upper ends of the tubes i, i, which pass
through the top of the case a and surround the rods e, e. The tube i in
each case has a flange at its lower end, on which lead weights k, k,
are placed. The tension of the spring f when the proper working strain
is upon it lifts the lever and the weights k until the uppermost weight
comes up to the cover of the case a. 1, 1, are levers on an axis by
which the valves can at any time be
It is the tension spring alone which holds the valve to its seat so long as
this spring remains in working order, but when it breaks it lets fall the
weight which then bears upon the valve, and so after the breaking of
the spring the valve remains loaded to an extent but slightly inferior to
the original load which the spring when in working order applied.
raised from their scats by hand.
Figure 4 is an elevation, and Figure 5 is a plan, both partly in section,
of another safety valve constructed according to my Invention; Figure 6
is a longitudinál section of the same. This arrangement differs from that
shown at Figures 1, 2, and 3, in that levers are dispensed with. The.
upper end of each tube i is prolonged, and has a long screw thread cut
upon it so that the nut can be set higher or lower, according to the
tension it is desired to give to the spring, which in this case is secured
to its lower end by clips directly to the nut . The upper end of the
spring is similarly secured to a head e* keyed upon the rod e. The
tension of the spring when the working strain is upon it lifts the weights
as in the former arrangement until the uppermost weight bears against
the cover of the case. The uppermost weight is provided with three
arms or wings in order to ensure a true bearing on the cover of the case.
m is a pipe to drain off any water which may condense in the case, as
beforé, in case the spring breaks the weights fall and serve as a load to
the valve. It is necessary on this construction that the load on the
valve after the spring has broken should be somewhat less than before,
but on the construction shown by the Figures 1, 2, and 3, it may, if so
desired remain unaltered; or even should there be any object in so
arranging it the load on the valve may be somewhat increased in con-
sequence of the fracture of the spring.
What I claim is, the construction of safety valves with springs and
weights, both available to load the valves, and so arranged that in case

page_text: of fracture of the spring the weight comes into action, substantially as
described.
In witness whereof, I, the said Samuel Wilkinson Snowden, have
hereunto set my hand and seal, this First day of December, in
the year of our Lord One thousand eight hundred and seventy-
four.