NOMENCLATURE OF PARTS OF GUN

Barrel. With asbestos packing; gun metal valve; side plates, left and right; side plate spring; connecting rod spring; protector for muzzle with chain and S hook.

Barrel Casing. With ejector tube spring; steam tube with slide valve; keeper screw; packing gland; asbestos packing; two screwed plugs, each with chain, S hooks, and stud; cork plug with chain and S hooks.

Breech Casing. With buffer spring; check lever with collar and split pin; slides, right and left; trigger bar; fusee spring box.

Cover. With joint pin, collar, and fixing pin; cover lock, with piston, spring, and stop screw; ammunition label with four rivets; cover springs.

Crank. With crank pin and fixing pin; connecting rod; crank handle and fixing pin; fusee with chain, spring, and adjusting screw.

Feed Block. With slide; top and bottom levers with spring fixing pin; top and bottom pawls, with axis pin; slide springs; feed block spring; band roller with axis pin, collar, and fixing pin.

Lock. Consisting of casing with side levers and screwed head; extractor levers, right and left; extractor with spring and fixing pin; gib with gib spring and cover; extractor stop with keeper and fixing pins; sear with spring and axis pin; trigger with axis and fixing pins; tumbler with axis pin; firing pin; lock spring, with axis and fixing pins; keeper bracket.

Rear Cross piece.  With fixing pin; firing lever with spring, axis, and fixing pins; safety catch and axis pin; piston and spring; shutter with pivot screw; milled heads with leather washers and oil brushes.

Sight, Fore. With fixing screw.

Sight, Tangent. Consisting of stem, graduated plate, and two fixing screws; slide with pinion, pawl, and fixing pin; tangent sight slide spring; milled head and fixing screw; axis pin; tangent sight spring and piston.

GENERAL DESCRIPTION

The gun may be considered as divided into two portions: the non-recoiling and the recoiling. It is worked automatically by two forces: the explosion of the charge, which forces the recoiling portion backwards, and a strong spring, (called the fusee spring), which carries it forwards. The non-recoiling portion consists of the barrel casing and breech casing, and is attached to the mounting by the crosshead and elevating joint pins.

The barrel casing is of gun-metal, holding about seven pints of water to keep the barrel cool when firing; it has three openings, one on the upper right side near the breech for filling, one underneath near the muzzle for drawing off the water, and the third (also near the muzzle) for allowing the steam but not the water to escape. The first two are closed with screwed plugs, the last is always open and connected with the steam tube. To prevent the escape of water, there is at the forward end of the barrel casing, asbestos packing, which is held in position round the barrel by the packing gland. At the rear end of the barrel there is a cannelure, also filled with asbestos packing, which prevents the escape of water when the gun is working and a gun-metal valve immediately in front of the block at the breech. which prevents the escape of water when the gun is not firing and the barrel home.

In addition, a cork plug is provided which can be inserted in the steam escape hole when the gun is travelling, in order to prevent waste of water from jolting. The plug should always be taken out before commencing to fire, and put in again before the gun changes position.

Under the barrel casing is the ejector tube through which the empty cartridge cases are ejected from the gun. The tube is fitted with a spring which prevents these cases falling backwards into the gun when firing.

When the barrel casing is filled with water about 2,000 rounds may be discharged at short intervals, without replenishing, but this depends on the rapidity with which the gun is fired.

Deliberate fire about 70 rounds per minute; rapid fire 450 rounds per minute.

The water commences to boil when the gun has fired with its greatest rapidity about 600 rounds; after this, if the firing is continued, the amount of water evaporated is about 1 pint for each 1,000 cartridges.

The steam tube is fitted in the barrel casing above the barrel, and is secured in its proper position by means of a keeper screw in the front of the barrel casing; it consists of two tubes, one fixed, having a hole near to each end, the other arranged to slide freely outside of it and termed the slide valve. If the gun is fired at elevation this valve slides backwards, and, closing up the hole at rear end of tube, prevents the water entering; at the same time, it leaves the front hole uncovered, which, being above the water level, allows the steam to enter the fixed tube and to escape through a hole bored in the solid part of the front end of barrel casing with which the tube is connected. Similarly, if the gun is fired at depression the valve slides forward and allows the steam but not the water to escape.

The breech casing consists of two outside plates, a bottom plate, and the rear cross piece, the whole being closed by a cover.

The outside plates are dovetailed into the barrel casing, and together with the cover are secured by means of the cover joint pin. On the outside of the right-hand plate there are the following fittings: a socket and stud for securing and supporting the buffer spring, the resistance piece, and the check lever, which pivots on a stud and is secured by a collar and split pin. On the outside of the left-hand plate are three studs for holding the fusee spring box, the rear one being on the slide mentioned below; also, there are two other studs on this plate provided for fixing a shoulder piece to the gun if required. In both plates are slots, in which the crank bearings move, partly closed by slides; on the inside of both are solid cams which control the path of the extractor.

The bottom plate is secured by rivets to the two outside plates; along the bottom lies the trigger bar, and underneath is a bracket to which is attached the elevating gear by means of the elevating joint pin.

The outside plates are connected at the rear end by the rear cross piece, into which they both dovetail; this piece is fitted with hollow handles for traversing, which are also used for carrying oil, these are closed by milled heads into which are fitted camel hair brushes, a firing lever the lower end of which is attached to the trigger bar, while the upper end is provided with a double button for firing, an automatic safety catch which is so arranged that unless it is held up the firing lever cannot be pressed forward, and a pivoted shutter which when moved to the right or left, uncovers an aperture through which (when the lock is removed and the crank handle vertical) the barrel can be inspected or cleaned from the rear.”

The cover is fitted with springs to ensure the extractor dropping on recoil, a gun metal block to keep the lock down when back, and at the rear end a lock to fasten it. On the upper surface is the tan- gent sight, which is graduated up to 2,500 yards.

The recoiling portion (which is mounted inside the non-recoiling portion) consists of the barrel and two side plates which carry the lock and the crank.

The barrel is coated with copper to protect it from rust; the gun- metal valve referred to above, which prevents the escape of water to the rear, is fitted just in front of the breech end, which is formed in the shape of a block; this block has a stud on each side which are called the barrel trunnions, and by means of them the barrel is attached to the side plates.

The side plates are each provided with a hole to receive the barrel trunnions and also guides in which the flanges of the lock move; in addition, each has a bearing through which the crank passes, thus connecting the latter with the barrel, these bearings move in slots in the breech casing. The left side plate is fitted with a connecting rod spring which holds the connecting rod upright when the lock is removed, and the right-side plate is fitted with a side plate spring near the barrel, the use of which is explained later. The left side plate is prolonged to the front, and has a recess in which the bottom lever of the feed block engages.

The crank is fitted on the right with a handle which has a curved projecting arm, and on the left with a fusee, to which is attached a chain; the remainder of the crank is inside the breech casing, while in the centre there is a connecting rod which is free to revolve on the crank pin.

On the left of breech casing there is a strong spiral spring, called the fusee spring, the rear end of which is connected by the fusee chain and fusee with the crank, the fore end is attached to the breech. casing by means of the fusee spring box and adjusting screw.

The action of recoil extends the fusee spring, winds the chain which is attached to it about the fusee, so that when the crank handle. is resting on the buffer spring, the fusee spring is not only extended about one inch by the recoil of the barrel, but the winding of the chain on the fusee causes a still further extension.

As soon as the recoil is exhausted, the action of the fusee spring is to pull the recoiling portion into the firing position and to unwind the chain off the fusee, thereby causing the crank handle to fly back. and strike the check lever, which is so constructed that when the crank handle reaches the stop, it is prevented from rebounding. The shape given to the buffer spring causes the crank handle when it strikes the former to assist the fusee spring in its action.

The lock is attached to the connecting rod by the screwed head, and when in the firing position closes the breech. In this position it is held by the side levers, the crank (which bears against stops on the side plates), and connecting rod, which are slightly above the horizontal, to prevent the breech being opened at the moment of explosion. The lock has a reciprocating motion communicated to it by the rotation of the crank, and is kept in position during its back- ward and forward movements by means of flanges working in guides on the side plates, and by the gunmetal block underneath the cover.

The extractor is attached to the fore end of the lock by guide ribs, upon which it slides, and is fitted with extractor spring, fixing pin, gib, gib spring, and cover. The projections on the extractor spring and gib, together with the cartridge grooves, form recesses which retain the cartridges in position.

The extractor is moved upwards by means of side and extractor levers, and when in its highest position, is retained there by means of a side plate spring, which ensures the hole for the firing pin being opposite the centre of the base of the cartridge when the lock is home. The upward and downward movements of the extractor are regulated by guide ribs and stops; the upper stop forms part of the lock casing, and the lower one is removable.

The gun is supplied with cartridges from a belt which passes through the feed block, on the top of the gun, from right to left. This belt is formed by two pieces of webbing connected together by eyelets and brass strips; the projecting ones showing how far the cartridges should be inserted in the belt, the latter is made thick at the edge next the bullets by being folded over a piece of cord, so that the cartridges may be kept parallel in passing through the feed block, and lie even in the ammunition belt boxes.

The feed block is provided with a slide to which are attached two pawls with springs for the purpose of moving the cartridges from right to left; the slide has a transverse motion given to it by means of two levers which are fitted together, the top lever has a slot which engages a stud on the slide, and on the bottom lever is a stud which engages in a recess in the left side plate, thus the slide is connected with the recoiling portion. There are also in the feed block two stationary pawls which project up under the belt and prevent it slipping back- wards during firing. To facilitate the entrance of the cartridges the feed block is provided with a band roller, and in addition has steel guides fitted above and below in the cartridge way, which ensure the cartridges coming to the exact position where they can be seized by the extractor; they are prevented from being pushed too far through to the left by means of the cartridge and bullet stops which are inside the feed block.

Weight of gun 60 lbs.

ACTION OF MECHANISM

Suppose the gun to have just fired; the explosion causes the recoiling portion to move backwards through a distance of about one inch, thereby driving the projecting arm of crank handle against the resistance piece, which latter, resisting this backward motion, forces the curve on the projecting arm of the crank handle to roll on itself, thus rotating the crank (thereby drawing back the lock), and causing the crank handle to strike the buffer spring; thus the greatest portion of the energy of recoil is transferred to the crank. The travel of the recoiling portion to the rear also moves the upper pawls in the feed block to the right so as to engage behind a fresh cartridge in the belt. When the lock moves backward the extractor withdraws the empty case from the barrel and a fresh cartridge from the belt in feed block. The extractor is kept in position by means of its horns, which move along the upper surface of the solid cams on the breech casing until the cartridge is clear of the belt; when it arrives at the rear end of these cams, it falls partly by its own weight, and partly by the action of the cover springs, thus bringing the cartridge drawn from the feed block in line with the barrel and the empty case drawn from the barrel in line with the ejector tube. When the lock is quite back it is kept in position by the block fixed to the cover, as its flanges are then clear of the guides on the side plates.

When the force of recoil is expended the action of the fusee spring comes into play, carrying the recoiling portion forward and revolving the crank by the unwinding of the fusee chain, thereby forcing the lock to the front. As the recoiling portion travels forward, it moves the upper pawls on the feed block slide to the left, and thus brings up automatically a fresh cartridge into position in the feed block, and a second cartridge in front of the bottom pawls. As the lock moves forward into the firing position, the live cartridge and the empty case are respectively placed in the barrel chamber and ejector tube, the extractor is moved upwards by the side levers acting on the extractor levers, thereby leaving the empty case in the ejector tube, where it is held by the ejector tube spring until pushed out by the next case, and causing the gib to slide over the base of the live cartridge in the chamber, thus bringing the firing pin hole opposite to the cap, and engaging a fresh cartridge which has been automatically moved up into position in the feed block. The turning of the crank handle on to the buffer spring not only draws the lock away from the barrel, but also gives a downward motion to the connecting rod and screwed head, which latter bearing on the tail end of the tumbler, rotates it on its axis, and the head of the tumbler being engaged in a recess in the firing pin, forces the latter to the rear, compressing the lock spring. When the bent of the tumbler has moved above the bent of the trigger, the latter is forced by the lock spring under the bent, and is thus able to hold the tumbler in the cocked position. The continued motion of the tumbler carries back the firing pin until the sear, (which is above and is acted upon by the sear spring), is forced into the bent of the firing pin and retains it. The firing pin is thus prevented from flying forward by two actions -viz., the sear and the trigger. In this position the trigger may be disengaged from the tumbler, but the sear will still prevent the firing pin from moving forward.

On the crank handle returning to the check lever the lock moves to the front, and the connecting rod and screwed head have an upward motion, so that when the lock is in the forward position the screwed head lifts the sear, thereby disengaging it from the firing pin, which then moves slightly forward until stopped by the bent of the tumbler engaging the bent of the trigger. If now the double button, on firing lever is pressed forward, the trigger bar is drawn backwards, at the same time a projection on the latter engages and draws with it the tail end of the trigger, thereby releasing the tumbler, the lock spring then propels the firing pin on to the cap and explodes the cartridge. If the gun has been set for rapid fire and the pressure on the firing lever is maintained as the lock moves forward, the lower end of the trigger comes in contact with the projection on the trigger bar, and its bent is thus withdrawn from the tumbler before the extractor has reached the firing position; the firing pin is therefore held only by the sear, and when the latter is lifted by the screwed head, the firing pin is released, and is thrown forward on to the cap by the action of the lock spring. The release of the sear from the firing pin is so timed that it cannot take place until the lock is in the firing position.

 

Acknowledgement:

This excerpt was transcribed from a PDF copy of the Handbook for the 0.303″ Maxim Machine Gun (Magazine Rifle Chamber), 1901 downloaded from the Vickers MG Collection & Research Association  website.

License:

The PDF was digitized by the Vickers MG Collection & Research Association and is shared for purposes and education and research and the Creative Commons License CC BY-NC-ND 4.0 has been applied to it. The license conditions can be found at https://creativecommons.org/licenses/by-nc-nd/4.0/