Improvements in the Breech Mechanism of Guns.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Breech Mechanism of Guns.
I, JOSIAH VAVASSEUR, a Companion of the Bath, of 8, Great George Street,
Westminster, in the County of Middlesex, do hereby declare the nature of this
invention to be as follows:-
According to this invention the breech block is not unlocked by turning it but
by turning a sleeve with the interior of which it interlocks.
The block and inside of the sleeve are conical and provided with spiral or snail
screw threads having a single interruption whilst the outside of the sleeve and the
inside of the breech are cylindrical and provided with continuous screw threads.
The breech block is unlocked by the recoil in the following manner:-The
sleeve has fixed to it a toothed segment gearing with a toothed segment on a
longitudinal shaft to which an arm carrying a roller is fixed. The roller works
on an incline on the cradle or guide bars in which the gun slides so that during recoil
the shaft is turned and the breech block is unlocked.
In order to withdraw the obturator and swing back the breech block clear of the
breech there are two longitudinal rods pivotted to the two arms of a lever pivotted
to the gun. During recoil one of these rods is arrested by a stop fixed to the
carriage causing the other to be projected rearwards from the rear of the gun and
act on the carrier of the breech block. Preferably the first rod carries a spring
box at its end to avoid shocks and breakage in case the obturator sticks whilst the
second rod instead of bearing directly against the carrier bears against one arm of
a tappet lever pivotted to it the other arm of the tappet bearing against the breech
of the gun.
The gun is closed and locked by means of a lever pivotted to the carrier and
lying between lugs on the sleeve.
In order to expel the powder gases from the bore of the gun compressed air is
led into an annular space around the bore between the rear of the latter and the
breech block. Directly the obturator commences to be withdrawn the air rushes
past it from this space and sweeps out the bore. The compressed air may be
supplied from a reservoir or from a cylinder fixed to the gun and having its piston
fixed to the mounting.
In some cases in place of employing interrupted screws on the breech block and
in the breech of the gun or the sleeve as the case may be I make the breech block
conical and employ a double threaded continuous screw.
Dated this 25th day of February 1898.

page_text: Improvements in the Breech Mechanism of Guns.
I, JOSIAH VAVASSEUR, a Companion of the Bath, of S, Great George Street,
Westminster, in the County of Middlesex, 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:
According to this invention the breech block is not unlocked by turning it but
by turning a sleeve with the interior of which it interlocks.
Figure 1 is a side elevation (partly in section), Figure 2 a rear elevation (partly
in section), and Figure 3 a plan of the rear part of a gun constructed according to
this invention.
a is the gun sliding between dovetailed side bars 6 to which the trunnions are
fixed. The breech block e is fixed instead of being pivotted as is usual to the
carrier arm c¹ which is pivotted to the gun at 2.
The block and inside of the sleeve dare preferably conical and provided with
spiral or snail screw threads having a single interruption (as described in the
Specification No. 25444 of 1897) whilst the outside of the sleeve and the inside
of the breech are cylindrical and provided with continuous screw threads.
The breech block c is unlocked by the recoil in the following manner: The
sleeve d has fixed to it a toothed segment gearing with a toothed segment el on a
longitudinal shaft e to which an arm c² carrying a roller e is fixed. The roller
works on an incline b' on the cradle or guide bars in which the gun slides so
that during recoil the shaft e is turned and the breech block is unlocked.
In order to withdraw the obturator and swing back the breech block clear of the
breech there are two longitudinal rods f and g pivotted to the two arms of a
lever h pivotted at h¹ to the gun. During recoil the rod f is arrested by a stop j
fixed to the carriage causing the rod g to be projected rearwards from the rear of
the gun and act on the carrier c¹ of the breech block. Preferably the rod f carries
a spring box f¹ at its end to avoid shocks and breakage in case the obturator
sticks whilst the second rod g instead of bearing directly against the carrier c¹
bears against one arm of a tappet lever k pivotted at ¹ to it, the other arm of the
tappet bearing against the breech of the gun.
The gun is closed and locked by means of a lever pivotted to the carrier and
ying between lugs m on the sleeve.
In order to expel the powder gases from the bore of the gun compressed air is
led into an annular space n around the bore between the rear of the latter and
the breech block c. Directly the obturator commences to be withdrawn the air
rushes past it from this space and sweeps out the bore. The compressed air may be
supplied from a reservoir or from a cylinder o fixed to the gun and having its
piston o fixed to the mounting, the cylinder being provided with suitable valves.
In some cases in place of employing interrupted screws on the breech block and
in the breech of the gun or the sleeve as the case may be I make the breech block
conical and employ a double or triple threaded continuous screw.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. A sleeve on the breech block free to rotate in the breech and by its rotation
interlocking with and unlocking from the block.
2. In apparatus such as is referred to in the preceding claim making the breech
block and the inside of the sleeve conical and the outside of the sleeve cylindrical.

page_text: 3. The combination of the breech, breech block and sleeve substantially as
described and illustrated in the drawings.
4. The combination with the subject matter of the preceding claims of a quadrant
fixed to the sleeve and a second quadrant gearing with the first and turned by the
recoil of the gun.
5. The combination with a breech block carrier pivotted to the gun of two rods
pivotted to a lever on the gun one of the rods during recoil coming against a fixed
stop thus causing the other rod to swing the carrier about its pivot.
6. Apparatus for swinging back the carrier substantially as described and
illustrated in the drawings.
7. Supplying compressed air to an annular space between the rear of the bore and
the breech block.
8. Breech mechanism for guns substantially as described and illustrated in the
drawings.