Improvements relating to Projectiles for Ordnance.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements relating to Projectiles for Ordnance.
I, HIRAM STEVENS MAXIM, of 18 Queen's Gate Place, in the County of Middlesex,
Mechanical Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to improvements in explosive projectiles or shells of the
class described in the Specification of former Letters Patent granted to me
January 14, 1890, No. 680, that is to say projectiles provided with means for
preventing the erosion of the bore of the gun when heavy charges of powder are
used therein.
According to my present invention I attach to the base or rear end of the pro-
jectile a cap or disc of gun metal or other suitable metal and arrange in combina-
tion with the same an obturating ring or gas check of asbestos and plumbago,
paraffine, wax or grease; or the said ring may be made of other suitable plastic
material. A portion of the rear end of the projectile is reduced in diameter to
form a shoulder and the obturating ring lies between the said shoulder and the
cap. The said cap is dished or bowl-shaped and is placed on the projectile with its
concave side outward and it has on its outer edge or periphery a forwardly pro-
jecting rim or flange which, previous to the discharge, is just in contact with the
said ring a space being left within the said flange between the cap and the base of
the projectile; but when the gun is fired the pressure on the cap flattens the same
against the base of the projectile thereby squeezing or compressing the obturating
ring so that it expands radially against the surface of the bore and makes a gas
tight joint between the projectile and the gun. By reason of the semi-fluid or
plastic condition of the substance of the said obturating ring and the relative sur-
face areas of the cap and of the ring the latter is subject to a greater pressure per
square inch than that existing in the gun after the discharge.
Improvements relating to Projectiles for Ordnance.
I, HIRAM STEVENS MAXIM, of 18 Queen's Gate Place, in the County of Middlesex,
Chevalier of the Legion of Honour, Civil and Mechanical 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:-
This invention relates to improvements in explosive projectiles or shells of the
class described in the Specification of former Letters Patent granted to me
January 14, 1890, No. 680, that is to say projectiles provided with means for

page_text: preventing the erosion of the bore of the gun when heavy charges of powder are
used therein.
"
According to my present invention I attach to the base or rear end of the pro-
jectile a flexible metal cap or disc provided with a rim or flange between which and
a shoulder on the projectile I arrange an obturating ring or gas check of suitable
plastic material, so that when the gun is fired the pressure of the generated gases
on the cap or disc causes the latter to be deformed and the obturating ring to be
squeezed or compressed whereby it expands radially against the surface of the bore
and makes a gas tight joint between the projectile and the bore of the gun.
In order that my said invention may be clearly understood and readily carried
into effect I will proceed to describe the same more fully with reference to the
accompanying drawings in which :-
Figure 1 is a longitudinal section of a portion of a gun barrel and a projectile
therein, provided with my present improvements.
Figure 2 is a similar view but shews the aforesaid cap or disc and the plastic
obturating ring in a position they assume after the explosion of the powder charge.
A is the projectile, B the cap or disc at its base, Ć the plastic obturating ring
and A¹ the ordinary driving ring.
The said cap or disc B is preferably constructed of gun metal and is normally.
dished or bowl-shaped as shewn in Figure 1. It is connected to the base of the
projectile by means of a screw with its concave side directed outward or towards
the rear and it has on its edge or periphery a forwardly projecting rim or flange B¹.
A portion of the rear end of the projectile is reduced in diameter to form the
shoulder a, in the annular space behind which the obturating ring or gas check C
is located as shewn. This ring is composed of plastic material such for example
as asbestos, plumbago, and paraffine wax or grease. The forward face of the rim
or flange B of the cap or dise B, previous to the discharge, lies in contact with the
said plastic obturating ring as represented in Figure 1, and by reason of the
curved or concave shape of the cap or disc it follows that a space exists between
the inner surface of the cap and the base of the projectile. When the gun is fired
the pressure of the generated gases acting on the rear surface of the said cap
flattens the same against the base of the projectile as represented in Figure 2
thereby squeezing or compressing the said plastic obturating ring C into the
annular space a¹ (Figure 1) that exists between the projectile and the bore, thus
producing an effectual gas tight joint between the projectile and the barrel or
bore of the gun. By reason of the plastic or semi-fluid condition of the substance
composing the said obturating ring and the relative surface areas of the cap B and
of the ring C, the latter is subjected to a considerably greater pressure per square
inch than that of the gas pressure existing in the gun.
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:
3
1. A projectile provided with a soft plastic obturating ring and a flexible cap or
disc which by its deformation or alteration of shape under pressure forces the said
plastic obturating ring against the surface of the bore for the purpose specified.
2. A dished and flanged cap or disc constructed and arranged to operate in con-
junction with a plastic obturating ring, substantially as described with reference
to the accompanying drawings.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.