Year: 1894

page_text: Date of Application, 24th Aug., 1894
Complete Specification Left, 23rd May, 1895-Accepted, 29th June, 1895
I JOHN DEWRANCE of 158 Great Dover Street, London, S.E., Engineer do
hereby declare the nature of this invention to be as follows:—
Water gauge cocks, test, salinometer, air, pressure gauge and other cocks that
are connected directly to the boiler are more secure if constructed in such a way
that the plug cannot under any circumstances he blown out while under pressure.
In the asbestos-packed cocks at present in use the plug if held in place by the
gland or one of the glands if there are two.
It is possible for a careless man to unscrew the gland, or to unduly screw it up
and strip the thread while the cock is under pressure, the result would be that the
plug would be blown out and the consequences might be serious.
I construct a cock of the kind that has packing in grooves parallel with the axis
of the plug joined by rings of packing at each end of the grooves, the packing in
the rings being compressed by glands; this arrangement of packing is common to
many of the forms of cocks in use. The plug of the cock I construct with the
stem, on to which the handle is fixed, at the smaller end of the taper part of
the plug.
The handle fits upon a square on the stem of the plug. At the end of the stem
I provide a screw thread on to which a nut fits. The handle rests upon the gland
and by the action of the nut the plug is drawn upon the couical bearing of packing
in the body. The nut may be a spring nut if preferred, and a split pin is passed
through the end of the stem to prevent the nut coming off.
At the other end of the plug I provide a hole to allow the pressure to pass freely
into the chamber formed by the gland or cap.
The tendency is therefore for the pressure to force the plug on to its bearing in
case the nut and washer may have been unduly eased off or have worn or become
slack from any cause.
With the form of cock described it is difficult to imagine any circumstances
short of fracture that could allow of a serious discharge of steam from the boiler.
Dated this 24th day of August 1894.
I JOHN DEWRANCE of 158 Great Dover Street, London, S.E., Engineer do
bereby declare the nature of this invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement :-
On the accompanying sheet of drawings Fig. 1, represents a sectional elevation
and Fig. 2 a sectional plan of a cock constructed according to my invention; A is
the body of the cock which may be suitably formed at either side to form a water
gauge or any other kind of cock. In the drawing the body A is broken off, the only
part shown being that which is necessarily common to all cocks constructed
according to my invention.

page_text: In the body A there are four grooves shown by B, B, in Fig. 2.
Into these grooves asbestos or other suitable packing is caulked, the strips of
packing in the grooves B, B, are united at either end by rings of packing C and D
which rings of packing are compressed by the glands E and F ; G is the plug
which is turned by a handle H fitted to a square M upon the smaller end of
the plug.
The handle H is arranged to slide upon the square M, & as it rests upon the
gland F, the pressure of the nut J turning upon the screw K draws the plug as
tightly as is desired on to its bearing of asbestos packing.
There is a hole L at the large end of the plug to admit the fluid pressure to the
space between the end of the plug and the gland or cap E so that the fluid pressure
keeps the plug on to its bearing in case the nut J is not properly adjusted.
It will be seen from the foregoing explanation and the drawing that even though
the gland E should be carelessly screwed off or stripped while under pressure the
cock could be shut off and the escape of fluid limited to the leakage between the
plug and body. The gland F cannot be unscrewed without first unscrewing
the nut J which nut is secured by a split pin N.
If the split pin N, the nut J, the handle H and gland F, were removed the escape
of fluid would be limited to the leakage between the plug and body unless the cap E
should also be unscrewed but such a procedure could not be carried out accidentally
as it would be manifest to anyone possessing sufficient knowledge to carry out the
operation that they were taking the cock to pieces.
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 :-
An improved cock the plug of which cannot be accidentally blown out by the
fluid pressure substantially as illustrated and described.
Dated this 23rd day of May 1895.
JOHN DEWRANCE.