Improvements in Stop and other Valves.
Year: 1893

page_text: Date of Application, 23rd Feb., 1893-Accepted, 13th May, 1893
COMPLETE SPECIFICATION.
Improvements in Stop and other Valves.
I, ALEXANDER TURNBULL of St. Mungo Works, Bishopbriggs, in the County
of Lanark, North Britain, Engineer, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in by and the following statement :-
This invention relates to improvements in stop and other valves for steam, air,
or other gases.
With the stop valves at present in use when they are opened the
full pressure is suddenly applied to the valve chest causing a sudden stress to come
on the sides of the chest. My object is to provide a valve by which the pressure
will be gradually applied to the steam chest. I attain this by constructing the
valve so that the first few turns of the handle for opening the valve will open only
a small orifice but after that the opening will be enlarged rapidly.
In order that my invention may be properly understood and readily carried into
effect I have hereunto appended two explanatory sheets of drawings, in the
several figures of which corresponding parts are marked with the same letters of
reference.
According to the modification of my invention as shown in Figure 1, by means
of two screws formed on the valve stem, one at the top and the other at the bottom
of a slightly less pitch, I cause the valve at first to open very slowly, but after a
few turns when the lower screw becomes free from its nut the valve is opened
quickly.
A is the valve, B the stem with handle C. The upper screw b works in a fixed
nut, and the lower screw b¹ works in a nut D fixed in a receptacle in the upper
part of the valve. When the handle C is turned to open the valve for each turn
of the handle the valve rises by an amount equal to the difference between the
pitches of the screws' and ', but after the screw leaves the nut D each turn of
the handle lifts the valve by an amount equal to the pitch of the screw b. Thus
at first the valve lifts very slowly, and the pressure is gradually applied to the
upper chamber.
In conjunction with the above described differential screw, or to attain the same
object alone I may construct the valve with a ring E, as shown on the right hand
side of Figure 1. This ring is formed on the under surface of the valve and slopes
downward towards the centre. By this arrangement the first opening of the handle
for the valve will give a very small orifice, and the increase in the orifice for each
succeeding turn will gradually increase.
Instead of the conical ring being attached to the valve I may attach it to the
valve seat as shown at E' on the left hand side of Figure 1, when it will be seen
that the same results will be obtained. In this case the conical ring may be held
down by lugs and screws H, as shown, and it may be used to keep the liner F, in
which the valve seat is formed, in its place; or the conical ring and liner may be
cast in one piece.
According to the modifications shown in Figures 2 and 3 I obtain the same
results by means of a small auxiliary valve, the valve seat of which is formed in
the main valve. This small valve is first opened either by the first few turna
of the stem of the large valve or by an independent stem of its own, and afterwards
the main valve is opened.
In Figures 2 and 3, A is the main valve, and a is the small auxiliary valve
which is first opened. In Figure 2 the first motion of the stem B for opening the
valve lifts the small valve a while the large valve A is held down in its place by
the strong spiral spring F between the flange a¹ and the top of the valve A. When

page_text: the flange a' rises' up against the saddle A' attached to the valve A the continued
turning of the stem B opens the main valve.
In Figure 3 a separate stem inside the main stem B and a handle e is provided
for opening the small valve first.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. The improvements in stop and other valves by which, on the valve being
opened the pressure is gradually applied to the steam chest and sudden stress on
the sides is avoided, substantially as described and illustred on the accompanying
.drawings.
2. The fixing down the valve seat by screws passing through lugs cast upon the
chest, and by cross bar upon the under side of the seat substantially as described
and illustrated on the accompanying drawings.
Dated this 22nd day of February 1893.
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Agents
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Agents