Improvements in Automatic Machine Guns.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Automatic Machine Guns.
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:-
My present invention relates chiefly to automatic machine guns in which the
energy for working the breech-mechanism is derived from the expanding force of
the gases escaping from apertures in the barrel near the muzzle, or from the
muzzle itself after the projectile has left the bore. The advent of smokeless
powder has made it necessary to introduce various new features in the construction
of automatic guns. For instance in many forms of cartridges the pressure
generated on discharge is very high and the projectile exceedingly light, cou-
sequently all of the parts of the gun have to be made of great strength and
considerable weight and, the recoil from a light projectile being feeble, it has
been found that the energy derived from the recoil is not sufficient to satisfactorily
work the breech mechanism. Moreover the high pressures generated have
demanded very thick percussion caps or primers so that very strong springs
requiring a good deal of force to operate them in cocking the hammer or firing
pin have become necessary. In order to obviate these new difficulties iny
improved gun is constructed with a non-recoiling barrel, all the energy for
working the breech mechanism being derived from the gases of discharge, and
the gases escaping from the muzzle, or through suitable lateral openings near the
muzzle, enter a large gas-chamber formed in the end of the water-jacket. The
outer end of this chamber is closed by a flap hinged at a point above the barrel to
the water-jacket and attached at the bottom to a rod in such a manner that when
the gases escape from the barrel they expand the air within the said gas chamber
by heat and also adding a part of their own volume to the gases and air already
in the chamber. This expansion throws the flap outward, pulls the rod and thereby
communicates the necessary movement to the breech mechanism of the gun and
also operates a spiral spring which gives off its energy for completing certain
functions of loading and firing.
Much trouble has been experienced on account of the primers of the cartridges
being unable to withstand the very high pressure they experience on firing; the
primers being sometimes forced out of the cartridges or having holes blown
through them. In order to obviate this objection I have provided a firing pin
which although it may be of considerable diameter will not be blown back at the
instant of firing, the hammer being arranged in such a manner that it locks the
firing pin in its fired position but unlocks it again after the gun is discharged.
The hammer is cocked as in other forms of my automatic guns.
In my present invention instead of using a toggle joint action for actuating the
breech-block or lock I provide the crank with a pin working in a slot in the lock
body the said slot being so forined and arranged that the lock moves forward but
slightly during the last portion of the augular movement of the crank in closing
the breech. The said crank is also provided with curved horns which are so
disposed with relation to lifting levers connected to the cartridge carrier, that the

page_text: latter is lifted into its elevated position and locked in this position, and then the
lock performs the slight forward movement above mentioned, by the crank pin
rising in the slot and pushing the lock forward against the breech of the barrel.
The upper portion of the said slot is advantageously struck from a centre slightly
below the centre about which the crank turns. In this manner all the lost motion
is taken up and the lock is very firmly held in position at the instant of firing
which prevents the breakage of cartridge cases.
By using a non-recoiling barrel I am able to connect it to the water-jacket near
each end, in such a manner that the water in the water-jacket does not escape
even under high pressure and I am also able to employ a valve so that the pressure
must reach several atmospheres before any steam can be blown off. This obviates
the dripping of water and at the same time prevents the water being blown off
with the steam, as is the case when only about one atmosphere of pressure exists
in the water-jacket. The crank handle is rotated by a bell-crank lever which is
connected to the rod passing from the aforementioned hinged flap. The bell-
crank lever is arranged in such a manner that it first gives a relatively slow
rotation to the crank and accelerates the movement thereof by gradually acting
on the crank nearer to its centre and further from the centre of the bell-crank
lever. The bell-crank lever is brought to a state of rest without shock, at the
same time giving a strong rotary motion to the crank-handle and all its attachments.
I provide a projection on the crank-handle which is arranged in such a manner
relatively to the bell-crank lever that when the crank handle is once started it
prevents the said bell-crank lever from prematurely returning into the firing
position and forcing the cartridge into the box too early, the parts not being
allowed to return until after the cartridge has been completely drawn from the
belt. This prevents crowding of cartridges in the feed-box.
In this gun if the cartridge belt should catch in the box or be prevented from
moving freely the crank-handle cannot return into the firing position until after
the bell-crank lever has been pushed back into the firing position and a new
cartridge fed into position in the feed box.
The fore-sight of the gun is attached to a projection on the water-jacket to
which the binged flap is pivotally counected. The feed-slide is actuated by a lever
which is operated by the same rod that communicates motion from the flap to the
breech mechanism of the gun. The spring employed for returning the flap and
its connecting rod into firing position and also for feeding the cartridges into the
feed-box is preferably contained in a telescopic tube placed inside the gun and
below the barrel.
These
The aforesaid lifting levers for operating the carrier are preferably articulated
to the lock body at the extreme end thereof, and are raised, to elevate the carrier,
by curved horns formed on or attached to the crank as already stated.
horns may act in conjunction with downward projections on the lifting levers and
as the said horns rise by the rotation of the crank in closing the breech, they
escape from beneath the projections on the lifting levers and continue their
movement without further raising the levers but still act to retain the said levers
in their uppermost position.
The method herein described of operating the breech block or lock and the
cartridge carrier is applicable to an automatic gun in which a recoiling barrel is
employed.
Dated this 21st
2000
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.

page_text: 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
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 chiefly to that class of automatic guns in which a non-
recoiling barrel is employed and in which the breech mechanism is actuated by
the gases of discharge, as they escape from apertures formed in the barrel near the
muzzle, or from the inuzzle itself, through the agency of a movable contrivance
situated at the muzzle of the gun. Certain of the improvements are however
applicable to guns having recoiling barrels.
The advent of smokeless powder has made it necessary to introduce various new
features in the construction of automatic guns. For instance in many forms of
cartridges the pressure generated on discharge is very high and the projectile
exceedingly light; consequently all of the parts of the gun have to be made of
great strength and considerable weight, and, the recoil from a light projectile
being feeble, it has been found that the energy derived from the recoil is not
sufficient to satisfactorily work the breech mechanism. Moreover the high
pressures generated have demanded very thick percussion caps or primers so that
it is necessary to use very strong springs, requiring great force to operate them in
cocking the hammer or firing pin. In order to obviate these difficulties my
improved gun is constructed with a non-recoiling barrel, the energy for working
the breech mechanisin being derived from the gases of discharge which escape
from the nuzzle or through suitable lateral openings near the muzzle and enter
a comparatively large gas-chamber whose outer end is closed by a hinged plate
or flap which is connected to the breech mechanism by
rod. When the hot
gases enter the gas chamber from the barrel, they expand the air within the said
chamber by heat and also add a part of their own volume to the gases and air
already in the chamber. This expansion, acting in conjunction with the energy of
the gases of discharge, throws the flap outward, pulls the rod and thereby transmits
the necessary movement to the breech mechanism of the gun and also actuates a
spiral spring whose re-action returns the flap to its closed position and completes
the operation of the feed mechanism.
Much trouble has been experienced on account of the primers of the cartridges
being unable to withstand the very high pressure to which they are subjected when
fired; the primers being sometimes forced out of the cartridges or having holes
blown through them. In order to obviate this difficulty I have provided a firing
pin which although of considerable diameter will not be blown back at the
instant of firing, the hammer being arranged in such a manner that it locks
the firing pin in its fired position but unlocks it again after the discharge of
the gun.
Instead of using a toggle joint for actuating the breech-block or lock I provide
the crank of my improved gun with a pin working in a slot in the lock body, the
said slot being so formed and arranged that the lock moves forward but slightly
during the last portion of the angular movement of the crank in closing the breech.
The said crank is also provided with curved horns or levers which are so
disposed with relation to pivoted lifting levers connected to the cartridge carrier
that the latter is lifted into its elevated position and there locked, and then the
lock performs the slight forward movement above mentioned, by the crank pin
continuing to rise in the slot and pushing the lock forward against the breech end

page_text: of the barrel. The upper portion of the said slot is advantageously struck from a
centre slightly beyond the centre about which the crank turns. In this manner all
lost motion is taken up and the lock is very firmly held in position at the instant
of firing which prevents the breakage of cartridge cases.
The crank-handle is rotated by a bell-crank lever which is connected to the rod
extending from the aforesaid hinged flap, the bell-crank lever being arranged in
such a manner that it first gives a relatively slow rotation to the crank and
accelerates the movement thereof by gradually acting on the crank nearer to its
centre and further from the centre of the bell-crank lever. The bell-crank lever is
brought to a state of rest without shock. at the same time giving an energetic rotary
motion to the crank-handle and all its attachments. I provide a projection on the
crank or the crank-handle which is arranged in such a manner relatively to
the bell-crank lever that when the crank-handle is once started it prevents the said
bell-crank lever from prematurely returning into the firing position and forcing
the cartridge into the feed-box too early, the parts not being allowed to return
until after the cartridge has been completely drawn from the belt.
I thus prevent
the crowding of cartridges in the feed box. If the cartridge belt should catch in
the box or be prevented from moving freely the crank-handle cannot return
into the firing position until after the bell-crank lever has been pushed back into
the firing position and a new cartridge fed into proper position in the feed-box.
I will now proceed to more fully describe my improvements with reference to
the accompanying drawings in which
Figure 1 is an elevation of the right side of a "Maxim"
Figure 2 is a vertical longitudinal section of the same.
gun.
Figure 2 is a transverse section of the barrel on the line a a of Figure 2.
Figure 3 is a plan with the cover-plate of the casing of the breech-mechanism
removed.
Figure 4 is a plan of the inner end of the rod by which the movement of the
hinged flap is conveyed to the breech-mechanism.
Figure 5 is a detail view shewing the crank-handle and bell-crank lever, seen in
Figure 1, in other positions.
Figure 6 is a vertical section of the muzzle portion of the gun shewing the
barrel terminating within the gas chamber instead of extending completely through
the same.
Figure 7 is a side elevation, and
Figure 8 is a vertical section of the breech-block drawn to an enlarged scale
with the parts thereof in the position they occupy when the breech is fully closed
and the gun has been fired.
Figure 9 is a similar section but with the parts in the position they occupy when
the breech is fully opened and the firing pin cocked.
Figures 10, 11 and 12 show respectively a longitudinal section, a plan and an
end elevation of the crank.
Figure 13 is a fragmentary view shewing a slightly modified construction of the
lifting levers and the crank arms for operating them.
Figures 14 and 15 are respectively a sectional elevation and front view of a
safety contrivance for locking the firing button in an inactive position.
Like letters indicate similar parts throughout the drawings.
A is the casing enclosing the breech-mechanism, and consisting of the side
plates a a¹ the top and bottom plates a³ a³, and the end plate a. a is the spring
catch for retaining the top plate or cover closed; B is the barrel; C is the
breech-block or lock; A'A' are the guide plates for the breech block or lock;
D is the crank shaft; D₁ the crank; G the spring which acts to return the crank
to its firing position; H the box or casing enclosing this spring; I the crank
handle; the buffer spring against which the crank-handle strikes in its forward
movement; K the roller over which the cartridge belt passes as it enters the gun;
and L the firing button.
The barrel B is, at its breech end, formed with recesses B' for the reception of

page_text: packing material so that a tight joint may be proluced between this part of the
barrel and the portion F' of the water-jacket F. The muzzle end of the barrel
passes through a stuffing box in a di-c or partition F' which is screwed into or
otherwise secured to the water-jacket a short distance from the muzzle end thereof
the said stuffing box being provided with a crew-threadel gland F³. Near the
muzzle end, the barrel has transverse openings bb through which the gases of
discharge pass into the gas-chamber d which is locate.l immediately in front or
the aforesaid partition F. The outer end of this gas-chamber is movable anl is
preferably made in the form of a flap d' which is hinged or pivoted at d to lugs d³.
This flap is provided with a lining of steel or other suitable material d and if
desired the gas chamber may likewise be provided with similar lining naterial.
The chamber d is connected to the partition F by a screw d and by the aforesaid
gland F One of the lugs d is adapted, to receive the fore sight d of the gun.
The muzzle of the barrel B projects through an aperture in the hinged flap, the
said aperture being made somewhat larger than the muzzle so that the flap can
freely turn about its hinge or pivot. Instead of arranging the barrel to extend
completely through the gas-chamber as shewn in Figure 2 the muzzle may
terminate within the gas chamber as she vn at Figure 6 and then the transverse
openings 6 will not be necessary. The aperture d' in the flap is however required
for the passage of the projectile. To the lower end d of the flap is connected a
rod d which extends along the underside of the water-jacket and has its inner
portion bifurcated or formed with two arms d10 d. One of these arins, viz.: d10
engages with the lower limb d" of a bell-crank lever that is pivoted at d* on the
exterior of the gun, this connection being effected by a pin d3 which extends
through a curved slot d" in the side plate a. The other of the said arms, viz.: dis
provided with a recess into which enters the lower end of an oscillatory lever die
(shewn in dotted lines in Figure 2). The upper end of this lever is forked to
engage with an arm s projecting from the axis s carrying the feed levers. This
feed lever operates the feed plate S by which the cartridge belt is fed through the
gun in the well known manner.
G is a spiral spring enclosed in telescopic tubes or shells g g the former
abutting against a fixed portion of the gun and the latter carrying a transverse
bar g' whose ends engage with recesses formed in the thickened portions d" of the
bifurcated part of the rod d; therefore when the hinged flap is forced outwardly
by the action of the gases entering the gas chamber d at each discharge, the
spring G becomes compressed and by its reaction it returns the said flap to its
closed position.
By employing a hinged flap in the manner above stated the gun is not rendered
unsightly or unsymmetrical in appearance. Moreover I am able to employ a
connecting rod which is always in tension, consequently great stiffness is not
necessary, and the rod can therefore be made much lighter than heretofore.
By making the gas chamber very large, as in my present invention, so that the
said chamber will contain a considerable quantity of air, it is found that the
parts do not have to fit tightly, that no objectionable incrustation takes place,
and that the pressure and temperature are both comparatively low so that the
parts do not get overheated. As the outer cylindrical wall of the said gas-
chamber is formed by the continuation of the water-jacket, the gas-chamber and
parts connected therewith are kept cool by the same water that cools the
barrel. Furthermore with my improved device, little if any disturbance takes
place, because at the time that the gas pressure is exerting its greatest force on
the parts, the surface of the hinged flap is practically perpendicular to the axis
of the barrel.
Another important advantage resulting from the use of the aforesaid hinged flap
is that its comparatively large area enables plenty of air to enter the gas chamber
at each shot, and this air, becoming heated by the gases of discharge entering the
said gas chamber, expands, so that the gun is therefore partly worked by hot air.
Moreover the said Hap is not liable to failure in its action and enables me to

page_text: obtain, with small cartridges, the requisite amount of power requirel for working
the gun.
Angular movement is imparted to the crank by means of the aforesaid bell-crank
lever, the limb d¹s of which acts on the eived surface D* of the crank-h in lle.
In order that the bell-crank lever shall not prematurely return after i has
imparted motion to the erank-handle, I provide the latter with a projection i
which is so arranged that as the end of the limb of the bell-crank lever acts on
the curved portion D of the crank-handle, to turn the latter, the aforesaid
projection arrives above the outer end of the said limb ds (see Figure 5) so that in
the event of the bell-ciauk lever at this time attempting to return, this projection i
will act as a stop to retard its return and will not release the bell crank lever
until the crank-handle has assumed approximately the position represented by the
dotted lines in Figure 3. By these means the lever d is prevented from being
operated by the rod d' and from actuating the cartridge belt fecd-plate S when a
cartridge has been only partially withdrawn from the belt. Crowding of the
cartridges in the feed-box is thereby avoided. Moreover, if, for any reason, the
cartridge belt should be prevented from moving freely through the feed-box, or
become fixed therein, so that the limb d of the bell-crank lever cannot with facility
return, this limb will retard the return movement of the crank-handle until the said
limb has regained its firing position and until a new cartridge has been fed into
proper position in the feed-box.
As in some of my former guus, I form the lock body with a curved slot C¹ in
which the crank-pin D works, but the curvature of this slot is, as already stated,
such that when the said crank-pin is moving in the upper part thereof, that is to
say during the last portion of the angular movement of the crank in elosing the
breech, the breech-block moves only to a slight extent. The cartridge carrier C²
here shown is similar to the well known kind used in previously constructed
Maxim guns and receives a vertical movement on the breech-block as the latter
reciprocates during the working of the gun. The means employed for lifting the
cartridge carrier and locking it in its raised position just before the completion of
the closing movement of the breech-block are however modified in construction as
follows: The crank D' is provided with curved horns D3 D³ whose outer curved
surfaces D are arcs of circles described from the centre of the crank shaft D
(see Figures 7, 8 and 10). Pivoted to the rear portion of the breech-block is a
pair of levers D D whose outer or forward ends D engage with lugs C³ on the
cartridge carrier. Extending downwardly from the underside of each lever D³ is
a projection D', the inner portion D of which is curved in correspondence with
the curvature of the surface D' of the horns D³. Therefore while the parts are in
the position represented by Figures 7 and 8 the aforesaid lifting levers D³ are firmly
held up and the carrier C is locked in its elevated position. These parts remain
in their locked position until, by the movement of the crank in opening the breech,
the upper ends D of the horns D³ come in alignment with the lower surfaces D
of the projections D'. The lifting levers are then no longer held in their locked
position by the horns D and can therefore turn downwardly about their pivots
when the carrier is depressed by the action of the ordinary cams A' and bracket A
(Figure 2) within the gun. During the return movement of the breech-block to
close the breech, and as the crank pin D is approaching the upper portion of the
slot C', the end D of each of the horns D³ strikes against the underside D10 of
each of the projections D' on the lifting levers D', as shewn by the dotted lines in
Figure 7, whereby the lifting levers are raised and the carrier elevated. The crank,
continuing its movement, causes the curved surface of the horns D' to slide against
the curved surface D of the projections D' without imparting further movement to
the lifting levers but firmly locking them and the cartridge carrier in their
elevated position, so that all movement of the said carrier is completed before the
final closing of the breech.
Instead of making the underside D of the projections D' flat as shewn in
Figures 7 8 and 9 they may be made curved at that part where the corners of the

page_text: horns D³ work against them, as shewn in Figure 13. In this case also the ends D
of the said horns are adapted to lie in contact with the underside of the lifting
levers.
The upper portion of the aforesaid curved slot C' is advantageously struck from
a centre at C (Figures 7 and 8) which is somewhat beyond and below the centre
about which the crank turns. In this manner all lost motion is taken up and the
breech block is very firmly held in position at the instant of firing and the breakage
of the cartridge cases is thereby avoided.
is
In order to lock the firing pin c in its fired position the nose ex (Figures 8 an19)
of the cocking lever or hammer c¹ is curved and the portion of the recess
likewise curved so that when the firing pin is impelled forward by the hammer c
to fire a cartridge, the aforesaid nose c* occupies the position represented by the
full lines in Figure & and lies against a shoulder e on the part of the firing pin.
The firing pin is thus locked in its forward position until the crank pin D', during
its downward movement in the slot C', acts uvon the tail of the hammer c¹, first
bringing it into the position represented by dotted lines in Figure 8 and finally
into the cocked position shewn in Figure 9, in which position it is held by the
sear c
For locking the firing button L in its safety position i.e. so that it cannot be
pushed inward, to fire the gun, I have provided immediately below the said firing
button a lever (Figures 14 and 15) having a hollow boss which enters a hole or
recess in the rear hinged plate a of the gun. The said boss is capable of turning
in this hole or recess when lateral pressure is exerted on the thumb piece 12. There
is a flange extending around the open end of the boss which Hange can enter a
13
notch in the firing button L. So long as this flauge engages with the said notch /^
the firing button cannot be operated, but by turning the lever until a recess / in
the flange coincides with the stem of the firing button, the said flange no longer
acts as a stop, and the firing button can then be pushed in. 11s a spiral spring one
end of which enters the aforesaid boss in the lever and the other end enters a
cavity in the firing button. The spring tends to keep the firing button in its
outward position.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim, in an automatic gun, is :-
1. The combination with a nou-recoiling barrel, of a gas chamber arranged at
the mouth of the water jacket and provided with a hinged or pivoted plate connected
with the breech mechanism of the gun and actuated by the gases of discharge.
substantially as described and for the purpose specified.
2. The construction and arrangement of the firing pin and cocking hammer
in such a manner that the latter will act to lock the firing pin in its fired position.
substantially as described and for the purpose specified.
3. The combination with the breech block or lock of a pair of lifting levers.
engaging at their free ends with the sliding cartridge carrier and having curved
projections to be acted upon by curved horns on the crank substantially as described
and for the purpose specified.
4. The breech block or lock having the slot in which the crank pin works
formed at its upper portion substantially as described and for the purpose
specified.
5. A projection on the crank for acting in conjunction with the bell-crank lever
whereby the latter is prevented from prematurely returning substantially as
described and for the purpose specified.
6. The combination with the rod for transmitting the movement of the movable
portion of the gas chamber to the breech mechanism, of a spring enclosed in a
telescopic casing one portion of which is coupled to the aforesaid rod and the other
portion of which is adapted to bear against the framing of the gun, substantially
as described.

page_text: 7. An automatic gun to which my improvements are applied substantially as
described with reference to the accompanying drawings for the purposes
specified.
Dated this 31st day of December 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.