Improvements in and relating to Fog Signalling on Railways with Detonators.
Year: 1898

page_text: Date of Application, 7th Mar., 1898
Complete Specification Left, 24th Sept., 1898-Accepted, 29th Oct., 1898
PROVISIONAL SPECIFICATION.
Improvements in and relating to Fog Signalling on Railways
with Detonators.
We, ERNEST ALBERT BENNETT BOWDEN and MILES CECIL IVES PARTRIDGE,
Railway Clerks, both of The Great Western Railway, Paddington, in the County
of London, do hereby declare the nature of our invention to be as follows:-
The objections to present systems of fog signalling by detonators placed on
the rail are that sometimes a detonator clipped on the rail is derailed or skidded
along with and by the engine wheels, and if twin detonators (that is to say two
detonators on one tin) are used the explosion of the first frequently blows out
the second which becomes a source of danger by getting amongst points and so
forth.
The objects of our invention are: 1st, To provide an attachment for detonators
by which they cannot be derailed or skidded, and 2nd, To save the number of
detonators exploded during fogs by reducing the number of useless explosions,
while at the same time continuing the old system of placing two detonators on the
rail.
In order to accomplish our first object, instead of providing the detonators
with side rail-clips as usual hitherto, we provide each with an attachment con-
sisting of a projecting strip of lead, tin, or the like of suitable length and adapted
10 be simply laid flat along the rail in the approach direction, so that it will be
engaged by the tread of the approaching wheel and so hold the detonator with
accuracy and certainty of explosion.
1
To accomplish our second object we provide means for withdrawing the second
detonator by the force of the explosion of the first, and in such a manner as to
leave the second uninjured and capable of being again placed on the rail; this
action may be repeated for an infinite number of times, thus saving one detonator
each time the first explodes. By this method two detonators are placed before
the engine for explosion, and in the event of the first failing to explode the
second is left on the rail, but the explosion of the first (which is a guarantee of
its having answered its purpose) serves to remove and save the second which is
no longer necessary. Under this system about half the number of detonators are
saved, while the same security against failure is preserved as under the old
system.
There are various methods by which this principle can be carried into operation.
According to one method the first detonator is mounted on the rail and at a
suitable distance is placed the second detonator. This has no clip but is mounted
on the end of a holder or strip of tin or other substance having a hole or socket
adapted to be mounted on a pivot set near the rail in such manner that it can
be swivelled on to and off the rail at will. When the engine explodes the first
letonator the force of its explosion serves to swing the second and unexploded
letonator out of the way of the wheels, and it can be replaced again by hand as
oon as the train has passed, and another first detonator again placed in position.

page_text: Or we may use a longer and suitably curved lever for the swivelling detonator
having at one end a socket for mounting on a pivot fixed near the rail and at
the other end a holder for the detonator so that it can be turned towards and
placed on the rail. At some point on this lever between socket and detonator
we fix a light impact plate adapted to, come about opposite to the first detonator
when in position, and the force of its explosion will then turn the lever and
second detonator away from and clear of the rail. If no explosion of the first
occurs the second detonator will of course remain on the rail. A stop, may be
arranged to limit the swing of the lever.
The essential feature of this part of our invention is the utilising of the force
of the explosion of a first detonator to derail and save the second so that it may
be re-used.
Improvements in and relating to Fog Signalling on Railways
with Detonators.
We, ERNEST ALBERT BENNETT BOWDEN and MILES CECIL IVES PARTRIDGE,
Railway Clerks, both of The Great Western Railway, Paddington, in the County
of London, 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:-
:-
The objections to present systems of fog-signalling by detonators placed on
the rail are that sometimes a detonator clipped on the rail is derailed or skidded.
along with and by the engine wheels, and if twin detonators (that is to say two
detonators on one tin) are used the explosion of the first frequently blows out
the second which is not only wasted, but may become a source of danger by
getting amongst points and so forth.
The objects of our invention are: 1st, to provide an efficient kind of attach-
ment for detonators by the action of which they cannot be derailed or skidded,
and 2nd, to save the number of detonators exploded during fogs by reducing the
number of useless explosions, while at the same time continuing the old system
of always placing two detonators on the rail.
In order to accomplish our first object we provide each detonator with an attach-
ment consisting of a projecting strip of lead, tin, or other more or less flexible
flat and thin material of suitable length and adapted to be simply laid flat along
the rail in the approach direction of the engine or vehicle, so that it will be
engaged by the tread of the approaching wheel and so hold the detonator with
accuracy and certainty of explosion.
In practice, we find it best to provide such an attachment SO that
it will extend about 4 inches on each side of the detonator at
right angles to the ordinary cross clips in order to render the detonator
reversible, and obviate the liability of a fogman inadvertently setting a detonator
with its tail attachment lying in the wrong direction (that is, not the approach
direction) and thus losing the benefit of the invention. Fig. 1 of the annexed
drawing shows in plan a detonator provided with our attachment on each side.
The kind of detonator we prefer to use has a circular body A with a dome-shaped
top (experience having shown this type to be the most efficient) and it is provided
with the usual side clips a a for embracing the top flange of the rail R. TT

page_text: are the tail attachment strips referred to, the one T projecting in the approach
direction of the train and the one T being provided as above explained for the
sole purpose of rendering the detonator reversible. The tail attachment or
attachments T T are secured by preference to the base of the body A so as to lie
as flatly upon and as closely to the rail surface as possible. They are about
4 inches in length and to an inch wide, or, if made of one strip and soldered
on the bottom of the detonator the strip would be about 11 inches in length in
order to extend 4 inches in each direction when flat upon the rail. The tail is
made of some metal such as thin lead or tin, or other suitable flexible material
may be used. It is important that such tail T shall lie quite flat on the rail and
not be crumpled up or tilted since in such case the action might be impaired.
We would here state that we are aware it has been proposed to construct
detonators of wedge-like form or of pyramidal shape with the object of enabling
the approaching wheel to get a hold of the thin end of the inclined part before
exploding the detonator in order to prevent skidding. Detonators of this kind,
2.e. made on any inclined plane system, cannot be made reversible without unduly
increasing the length, and if not reversible and laid in the wrong direction an
approaching wheel would strike the higher end and almost certainly derail the
detonator without exploding same. We lay no claim to any inclined plane con-
struction of detonators.
To accomplish our second object we provide means for withdrawing the second
detonator by the force of the explosion of the first and in such a manner as to
leave the second uninjured and capable of being again placed on the rail, thus
saving one detonator each time the first explodes. By this method two detonators
are always placed before the engine or vehicle, and in the event of the first failing
to explode the second is inevitably left on the rail, but the explosion of the
first detonator (which is a guarantee of its having answered the purpose) serves
to remove and save the second which is no longer necessary. By this means about
half the number of detonators usually exploded will be saved, while the same
security against failure is preserved as under the old system.
There are various methods by which the principle above explained can be
carried into operation and several alternative arrangements are shown in the
drawings, in Figs. 2 to 8 of which the train is supposed to be approaching from
the direction of the arrow. Referring to Figs. 2 and 3 which are respectively a
plan and elevation of one arrangement, the first detonator A¹ is mounted on the
rail R by cross clips a a in the usual way and at a suitable distance is placed the
second detonator A². This has no rail clips but it is mounted on the end of a
holder S of tin or other material having a hole or socket at s adapted to be
mounted on a pivot P set near the rail in such manner that it can be swivelled
on to and off the rail with ease. When the engine or leading wheel explodes the
first detonator A¹, the force of its explosion serves to swing the second and un-
exploded detonator A2 out of the way of all the wheels, and it can be replaced
again by hand as soon as the train has passed, and another first detonator again
placed in position; to better concentrate the force or blow caused by the explosion.
of the first detonator a plate (which we call the "impact plate") may be fixed where
dotted at B as hereinafter explained. Another arrangement is shown in Figs. 4
and 5 respectively in plan and end elevation in which we use a longer and
suitably curved lever L for the second or swivelling detonator A2 having at one
end a sockets for mounting on a pivot P fixed near the rail as above described
and at the other end a holder S for the detonator A2 so that it can be turned
towards and placed on the rail. At some point on this lever between socket and
detonator we fix the "impact plate" so that it will come about opposite to the
first detonator A¹ when in position, and the force of its explosion acting on the
impact plate" B will then cause the lever L to be turned and to withdraw the
second detonator A2 away from and clear of the rail and wheels. A stop or catch
such as I may be arranged to limit the swing of the said lever.

page_text: A third alternative arrangement is shown respectively in plan, end view and
elevation in Figs. 6, 7 and 8. This arrangement differs from that described in
reference to Figs. 4 and 5 in that the lever L is rotary instead of swinging. It
is mounted horizontally and parallel with the rail in standard bearings C, and
adapted to rotate freely therein. The impact plate B is mounted at or near one
end of the lever L about opposite the first detonator A' and the second detonator A
is clipped to the end of a holder H pivotted loosely by a pin h to a lever L' fixed
to the end of the lever L and extending upwards to about rail level. Stop
holes adapted to receive stop pins e e are provided on a downward extension
of the lever L¹ for the purpose of regulating the oscillation of the lever L and
such stops may be arranged on either side of the lever L' so as to enable the fog-
man to work towards the left or towards the right according to circumstances.
It will be seen that the impact caused by the explosion of detonator A¹ will
cause the lever L to be rotated and to pull the detonator A2 off and clear of the rail.
The changes of position are shown in dotted lines in the figures. In all these
cases if no explosion of the first detonator A¹ occurs the second detonator will,
of course, remain on the rail.
The essential feature of this part of our invention is the utilising of the force
of the explosion of a first detonator to derail and save the second detonator so
that it may be re-used and the scope of our claims is intended to cover broadly
means for carrying the principle into operation.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is :-
1. A detonator for use in fog-signalling with an attachment consisting of a
projecting strip or strips of lead, tin or other flexible material adapted to lie flat
along and upon the rail surface, so that the strip projecting towards an approach-
ing vehicle will be engaged by the tread of the leading wheel, for the purpose
of preventing skidding of the detonator and holding same in position with
accuracy and certainty of explosion, as above described and illustrated in the
drawings.
2. In fog-signalling on railways with detonators, utilising the force of the
explosion of a first detonator to derail and save the second detonator, so that
the latter may be re-used and useless explosion saved, substantially in the manner
above set forth.
3. Means for accomplishing the object referred to in the 2nd Claim, such as
are described in reference to and illustrated respectively in Figs. 2 to 8 of the
drawings annexed hereto.