Improvements in Detonators for Railway Signalling.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Detonators for Railway Signalling.
J, VICTOR VON NEUMAN, of I, Riemergasse, 13, Vienna, in the Empire of Austria,
Manufacturer, do hereby declare the nature of this invention to be as follows:-
This invention relates to safety detonators for railway signalling which are
placed upon the rails and caused to explode by the wheels of the train passing
over them. These detonators should fulfil the following requirements:-
-
1. They should explode with a report sufficiently loud to be overheard by the
engine-driver under the most unfavourable conditions as regards weather;
2. They should be capable of withstanding shock, damp, and other accidental
external influences and yet be able to be stored without deteriorating;
3. When detonated by the impact of the wheel they should not cause the dis-
persion of fragments and splinters.
Although the first two requirements are more or less completely fulfilled by
the explosive fog signals now commonly in use, the third requirement has not
yet been successfully met (except by the use of special protective caps) that is
to say there is no known detonator which when exploded will not cause fragments
or splinters to be hurled through the air at the risk of injuring bystanders or
adjacent objects. The object of this invention is to provide for the fulfilment of
the third requirement.
Each detonator consists of three essential parts, the detonating charge, the
casing, and means for securing the signal to the rail.
Heretofore the casings have been of uniform strength or resisting power through-
out, whatever the material employed, and consequently the charge when exploded
has to overcome a uniform resistance in all directions and hence the situation
of the point at which the gaseous products of explosion make their escape has
been a matter of chance. Therefore since the casing is prevented from bursting
out on the rear and inner sides by reason of the rim and flange of the wheel
bearing on these portions of the casing, the latter. usually bursts towards the
outer side of the rail in a forward direction or at the points of greatest danger,
the danger having increased by reason of the custom of employing stable high
explosives almost exclusively in order to enable the detonators to fulfil the 'two
first requirements first mentioned above. To remedy this defect the casing,
according to the present invention, is constructed in such manner that the power
of resistance of the parts of which the casing is composed differs, the top part
being much stronger in this respect than the bottom. These parts of the casing
are fastened together so as to constitute a water-tight joint and the detonating charge
is enclosed between them. When the explosion takes place the weaker lower part
is separated from the upper part along predetermined lines of division, that is to
say the mutual attachment of the parts being secured merely by pressure along
their overlapping edges the lower portion under the disruptive influence of the
expanding gaseous products of combustion is disconnected from the upper part
along its edges and bent downwards over the head of the rail while the stronger
upper part remains unaltered and thus constitutes a shield so that any small

page_text: fragments produced are in part caught by this unaltered upper portion and in
part directed downwards in the immediate vicinity of the rail and are thus rendered
innocuous.
In place of the mercury fulminate hitherto employed for the detonating charge
black powders of low explosive force and stability are preferably employed in the
subject of the present invention, the said detonating charge being incorporated
with one or more ignition caps resting on nipples.
In order to render this improved signal visible as well as audible it is advisable
to combine the explosive charge with illuminating charges such as are well known
in pyrotechnics.
The attachment of the casing of these new signals to the rails may be effected
in any suitable way hitherto practised and according to circumstances.
Dated this 28th day of September 1899.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
Improvements in Detonators for Railway Signalling.
I, VICTOR VON NEUMAN, of I, Riemergasse 13, Vienna, in the Empire of Austria,
Manufacturer; 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 and
by the following statement:---
This invention relates to detonators for signalling on railways by explosion under
the wheels of the trains. Such detonators should fulfil the following require-
ments:-
1. Explosion with a sufficiently loud report to be heard by the engine-driver
under the most unfavourable conditions of weather;
2. Capability of withstanding shock, damp, and other accidental external
influences, without liability to deterioration in store;
3. Detonation under the wheel without the dispersion of fragments and splinters
of the detonator casing.
Although the first two conditions are more or less completely fulfilled by the
explosive fog signals now used, the third requirement has not yet been success-
fully met (except by the use of special protective caps) there being no detonator
in use which is not liable on explosion to cause the dispersion of fragments or
splinters of its casing which may injure bystanders or adjacent objects. The
object of this invention is to provide for the fulfilment of the third requirement.
A detonator comprises three essential parts, riz., the detonating charge, the
casing, and the means for securing it on the rail
Heretofore the casing has been of uniform strength or resisting power through-
out, whatever the material of which it is made, and consequently the charge
when exploded has to overcome a uniform resistance in all directions and hence
the pressure point where and the direction in which the gaseous products of
explosion make their escape is not predetermined. Therefore since the casing
is prevented from bursting towards the rear and towards the inside of the rail
by the pressure of the tread and flange of the wheel, the casing usually bursts in
a forward and outward direction, that is to say in the direction of greatest danger,
which is all the greater from the fact that stable high explosives are used almost
exclusively in order that the first two requirements shall be fulfilled.
According to the present invention the casing in which the charge is enclosed
is constructed in such manner that the power of resistance of the parts of which

page_text: the casing is composed differs considerably, the top part being much stronger than
the bottom part. These two parts of the casing with the charge enclosed between
them are fastened together so as to make a water-tight joint, but when the explosion'
occurs the weaker lower part is separated from the upper part along a pre-
determined line of division, that is to say the mutual attachment of the parts
being ensured merely by pressure, the lower portion under the disruptive influence
of the expanding gaseous products of combustion becomes disconnected from the
upper part and bent downwards over the head of the rail while the stronger upper
part remains practically unaltered in shape and constitutes a shield or deflector
by which any small fragments projected will in part be caught and in part be
directed downwards in the immediate vicinity of the rail.
In lieu of mercury fulminate hitherto employed for the detonating charge non-
shattering stable black powders are preferably employed in the manufacture of
these detonating signals, the charge being incorporated with one or more ignition
caps resting on nipples.
In order to render this improved signal visible as well as audible it is advisable
to combine with the explosive charge an illuminating charge such as is well
known in pyrotechnics.
The attachment of the detonating signals to the rails may be effected in any
suitable way hitherto practised and according to circumstances.
The invention is illustrated in the accompanying drawings forming part of
this specification, wherein Figures 1 and 2 respectively represent a plan and
longitudinal section of a safety detonator containing either two explosive charges
or one explosive and one illuminating charge, as indicated at 1 and 2 in Figure 1.
3 is the strong upper part of the casing and 4 the relatively weak under part
of the casing, the parts 3 and 4 being united at 5 by the edge of the upper part
being lapped or folded over that of the lower part and pressed so as to make a
water-tight joint.
Figure 3 shows a single detonator having but one explosive, or combined
explosive and illuminating charge. Figure 4 shows the detonator as attached
to the rail in the usual manner by means of clips 7, whilst Figure 5 shows the
detonator held in position on the rail by means of a clip 9 carried by an elbow
lever S.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:
1. A safety detonator whereof the casing is made of two parts (a top and bottom
part) between which the charge is enclosed watertight, the top part having con-
siderably greater strength of resistance than the bottom part in order to ensure
the liberation of the gaseous products of combustion in a predetermined direction,
as described.
2. In a safety detonator whereof the casing is made as hereinbefore specified and
claimed, the employment of an explosive charge consisting of non-shattering stable
black powder incorporated with ignition caps resting on nipples, as described.
3. In a safety detonator whereof the casing is made as specified in Claim 1 the
combination of an illuminating charge composed as specified in Claim 2.
Dad his 22.l day of Tune 1000
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London,