Improvements in Firing Mechanism and Fuzes or Primers for the Ignition of Cartridges in Guns.
Year: 1887

page_text: Date of Application, 3rd June, 1887
Complete Left, 5th Mar., 1888
Complete Accepted, 6th Apr., 1888
Improvements in Firing Mechanism and Fuzes or Primers for the
Ignition of Cartridges in Guns.
I, CHARLES AMBROSE McEvoy of the London Ordnance Works, Bear Lane,
Southwark in the County of Surrey, Engineer, do hereby declare the nature of
this invention to be as follows:-
The object of the invention is mainly to admit of cartridges having either an
electric or a percussion primer being used with quick firing guns.
For this purpose I form the ordinary striker or hammer which is carried within
the breech block of a quick firing gun with its striking end insulated and connect it
by an insulated flexible conductor with an insulated terminal at the back or side of
the breech block and this terminal 1 couple by a flexible conductor or otherwise with
one pole of a battery.
Or in place of forming the hammer with an insulated striking end to be coupled
to one pole of a battery the insulated striking end may be carried by a spring and be
struck and thrust forward by the hammer when it falls.
When the hammer is thrown forwards by its spring to fire the gun it will if the
cartridge is fitted with a percussion primer ignite it by the blow or if it is fitted with
an electric primer or fuze then when the striking end of the hammer comes into
contact with the end of the central stem of the fuze an electric current will pass
through the fuze to the metal of which the gun is composed and through it to the
opposite pole of the battery and the fuze will be ignited by the passage of the electric
current. The primer or fuze whether electric or percussion is screwed or inserted
into a recess in the centre of the rear end of the cartridge case.
The fuze when electric I form in a somewhat similar manner to that described in a
provisional specification lodged by me with an application for patent No. 3469-in the
present year except that I make the insulated central stem of the fuze with a flange
projecting around its rear end to bear against the back end of the outer cylinder so
that the central stem of the fuze may not be driven forwards out of place when it is
struck by the hammer.
Preferably I make it as a screw with a head to bear against the back end of the
outer cylinder and with its screw stem to pass through a hole in this end and screw

page_text: into the insulated stem or piece of metal which is within the outer case and to which
one end of the platinum wire is attached.
When a percussion primer is to be used I make it externally of the same shape as
the electric one so that either one or other may be used. I make it with an anvil or
nipple screwed into its front end to carry a cap the cap I bring into contact with a
metal stem which passes through a hole in the centre of the back end of the outer
cylinder and this stem I form with a flange around its inner end to bear against the
inner face of the end of the case so that it cannot drop out or be forced out by the
pressure of the powder gases. When the rear end of the stem is struck by.
the hammer it is forced inwards against the cap and ignites it.
Dated this 3rd day of June 1887.
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Firing Mechanism and Fuzes or Primers for the
Ignition of Cartridges in Guns.
I, CHARLES AMBROSE MCEVOY, of the London Ordnance Works, Bear Lane,
Southwark, in the County of Surrey, 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 and by the following statement :-
The object of the invention is mainly to admit of cartridges having either an
electric or a percussion primer being used with quick firing guns.
For this purpose I form the ordinary striker or hammer which is carried within
the breech block of a quick firing gun with its striking end insulated and connect it
by an insulated flexible conductor with an insulated terminal at the back or side of
the breech block and this terminal I couplo by a flexible conductor or otherwise with
one pole of a battery.
Or in place of forming the hammer with an insulated striking end to be coupled
to one pole of a battery the insulated striking end may be carried by a spring and be
struck and thrust forward by the hammer when it falls.
When the hammer is thrown forwards by its spring to fire the gun it will if the
cartridge is fitted with a percussion primer ignite it by the blow or if it is fitted with
an electric primer or fuze then when the striking end of the hammer comes into
contact with the end of the central stem of the fuze an electric current will pass
through the fuze to the metal of which the gun is composed and through it to the

page_text: opposite pole of the battery and the fuze will be ignited by the passage of the electric
current. The primer or fuze whether electric or percussion is screwed or inserted
into a recess in the centre of the rear end of the cartridge case.
The fuze when electric I form in a somewhat similar manner to that described in
a specification lodged by me with an application for patent No. 5469 in the year 1887
except that I make the insulated central stem of the fuze with a flange projecting
around its rear end to bear against the back end of the outer cylinder so that the
central'stem of the fuze may not be driven forwards out of place when it is struck. by
the hammer.
Preferably I make it as a screw with a head to bear against the back end of the
outer cylinder and with its. screw stem to pass through a hole in this end and screw
into the insulated stem or piece of metal which is within the outer case and to which
one end of the platinum wire is attached.
When a percussion primer is to be used I make it externally of the same shape as
the electric one so that either one or other may be used. I make it with an anvil or
nipple screwed into its front end to carry a cap the cap I bring into contact with 'a
metal stem which passes through a hole in the centre of the back end of the outer
cylinder and this stem I form with a flange around its inner end to bear against the
inner face of the end of the case so that it cannot drop out or be forced out by the
pressure of the powder gases. When the rear end of the stem is struck by the hammer
it is forced inwards against the cap and ignites it.
Figures 1 and 2 of the drawings hereunto annexed are longitudinal sections of
the breech end of a Hotchkiss gun the construction of which is well known with
firing mechanism formed as above described applied to them.
In Figure 1 A is the body of the gun-B the sliding breech block-and C the
striker or hammer carried as usual within a narrow slot formed in the breech block.
Its striking end or point is as usual carried by a readily removeable blade C¹ fixed to
the front of the hammer but in place of being formed in one piece with this blade it
is formed as a separate piece to screw into a block of insulating material D which is
itself screwed into the blade C¹.
E is a flexible insulated wire secured to the stem of the striking point and led
away to an insulated terminal Fat the rear of the lower part of the breech block.
The front of the breech block is formed as usual of a readily removeable plate B' so
that the lock mechanism may readily be got at for repairs.
In the modification shewn at Figure 2 the blade in place of being fixed to the
front of the hammer is fixed to the back of the plate B' insulating material being
interposed between them and an insulated conductor led away from the blade
through the bottom of the block B.
Or
In this case the blade C serves as a spring to hold back the striking point so that
it does not project from the face of the block until struck by the hammer.
especially if electric fuzes only are to be used in the gun cartridges it might if
dosired be arranged to press the point forwards so that it may come into contact with
the rear end of the central metallic conductor of the fuze immediately that the breech
is closed. In this case the hammer might be dispensed with and the firing might
be controlled by a separate contact maker or firing key.
The way in which I form the electrical fuzes for the cartridges is shewn in
longitudinal section at Figure 3.
G is the outer cylindrical body formed to screw into the rear end of the cartridge
case at its centre-H is the insulated metallic central stem-I are fine wires of
platinum passing from the front end of this stem to the outer metallic body G-
H is the flange formed on the rear end of the stem H to prevent it from being driven
forward when struck by the hammer.
The way in which I form the percussion primers for the cartridges is shewn in
longitudinal section at Figure 4.
It is made externally of the same shape as the electric fuze-internally it has the
anvil K screwed into it for the cap L to be forced against and through the centre of
it's rear end is passed a metal stem M which when struck by the hammer can be

page_text: driven inwards against the cap to explode it and which is formed with a flange M¹.
around its inner end to come against the inner face of the back of the outer body G
and prevent its being forced back by the pressure of powder gases when the cartridge
is fired. Another way in which a percussion fuze could be formed is shewn at
Figure 5.
Having now particularly described and ascertained the nature of iný said:
invention and in what manner the same is to be performed I declare that what'
I claim is :-
1. The construction of firing mechanism for breech loading guns substantially as
herein before described and illustrated at Figure 1 in such manner that cartridges
fitted with percussion or electric fuzes may be used with it.
2. The construction of firing mechanism for breech loading guns substantially as
herein before described and illustrated at Figure 2 in such manner that cartridges
fitted with percussion or electric fuzes may be used with it.
3. The combination with hollow sliding breech blocks formed with a readily
removable plate at the front of an insulated contact point coupled by a spring to the
back of the plate and an insulated conductor led away from it substantially as
described with reference to Figure 2.
4. The construction of electrical fuzes for cartridges substantially as herein.
before described with reference to Figure 3.
5. The construction of percussion fuzes for cartridges substantially as herein
before described with reference to Figure 4.