The 2-barrelled 1 inch Nordenfelt machine gun was a significantly lighter large calibre machine gun. It could be carried and fired from ships boats and mounted in the fighting tops of medium and small ships, where it would have an unrestricted arc of fire, and from where the small torpedo boats could best be seen. The 2 barrel gun shown here operates on Nordenfelt's Second system.
2 Barrel Nordenfelt Machine Gun
Action block for 2 barrel Nordenfelt (rollover)
Trigger comb with both hammers cocked
Breech piece showing 2 plungers, and action slot
Cartridge carrier showing movement due to breech piece (rollover)
Action of the 2-barrel Nordenfelt mechanism
Operation of Action lever on action block and breech piece (rollover)
The 2-barrel was intended for the armament of torpedo boats and for positions where the weight of the 4-barrel precludes it being placed. It was capable of firing 60 shots per minute in rapid fire, but fewer aimed shots when mounted in small craft. It fired the same cartridge as the 4-barrel gun, and should have penetrated a torpedo boat out to 1,500 yards.
In this gun the objectionable motion of the action block to the rear is avoided, and thus the mechanism is made more compact and less liable to injury. The principal parts of the mechanism are:-
a. Hand lever
b. Action lever
c. Action block
d. Breech piece
e. Trigger comb
f. Cartridge receiver
The hand lever is pivoted on to the axis pin, and sets the whole mechanism in motion. The action lever is fixed to the axis pin, and has a stud on which a friction roller revolves.
The breech piece consists of a plate with two plungers, containing the two firing pins and claw extractors. Beneath this plate is fixed the action slot (shown as a slot completely through the plate in the animation), in which the action lever friction roller works, affording the breech piece longitudinal motion only. On the upper surface of the plate are two studs (light blue) which catch the lower T-projections of the hammers, forcing them back, and thus compressing the firing springs. A lug on each side of the breech piece (shown in green) acts against the corresponding lugs on the cartridge receiver, and thus forces it to the right and left, as the handle is moved forwards or back.
The action block is placed at the rear of the breech framework, and has only transverse motion. In it are two slots for the plungers to pass through. In the solid parts, between the slots, chambers are bored for the firing springs and hammers to lie in. The hammers have each a T-shaped projection. Through the middle part of the action block, a channel passes from right to left for the reception of the trigger comb.
The trigger comb has a small spring to bring it to the right and so retain the hammers after they have passed the two teeth on its lower surface. The trigger comb, which projects to the right of the action block, is forced against the right side of the framework on the action block moving to the right, and the trigger comb is thus pushed to the left and releases the hammers.
The cartridge receiver is given its lateral movement by lugs on the breech piece. When the breech piece is almost fully retracted to the rear of the frame, a lug on the right side engages with an angled lug cut into the cartridge carrier, which forces the carrier to the left of the gun frame. The waiting cartridge then falls into the trough of the carrier. The cartridge is held in the trough since it is shaped so that the head of the cartridge is wider than the slot at the bottom of the trough, and the projectile rests on the solid part of the carrier.
As the operating hand lever is pushed forwards, the breech piece moves forwards, and the (green) lug on the breech piece forces the cartridge carrier to the right, thereby placing the fresh cartridges in line with their respective barrels. After firing, the empty cartridge is drawn back until the cartridge head passes a cutout at the rear of the trough which then allows it to fall to the ground.
The Action Described
The action of the mechanism is as follows, supposing the hand lever to be in its most forward position and the gun just fired.
First: the handle moves to the rear and the tail of the action lever (dark green) carries the action block to the left of the gun (upwards in the animation).
Second: the openings in the action block for the plungers being in the same line with them, the action lever roller working in the action slot, carries the breech piece with plungers to the rear, at the same time withdrawing the empty cartridge cases, which drop to the ground through the holes in the cartridge receiver troughs.
Third: the studs on the upper surface of the breech plate (light blue) catch the lower part of the hammer T-projections, forcing the hammers back and against the bevelled edges of the trigger comb teeth, which is then moved against its spring to the left (upwards in animation) until the hammers are clear, when the spring carries the trigger comb back to its normal position with the teeth in front of the hammers. At the same time the hammer springs are compressed, and the cartridge receiver brought to the left. Fresh cartridges fall into the troughs. The handle has now reached its rearmost position.
Handle Pushed Forwards
First: The cartridge receiver is moved to the right, placing two fresh cartridges in front of the barrels. Then the breech piece with its plungers is carried forward and pushes these cartridges into their respective barrels.
Second: The cartridges being quite home, the action block is moved to the right, and the hammers are thus brought directly behind their firing pins. At the same time the projecting part of the trigger comb is carried against the framework of the gun, causing the trigger comb to be pushed to the left, freeing each hammer in turn, which, flying forward strike the firing pins and thus fire the cartridges.[N1].
Other Guns using the Second System
The mechanism described above is used in the 2- and 3-barrelled rifle-calibre guns, and also the 2-barrel shell gun. The Mark II version of the 5-barrel rifle-calibre machine gun also used this system, while the earlier version used the first system, invented by Palmcrantz.
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