Page:EB1911 - Volume 17.djvu/257

 The idea of using the recoil, or a portion of the gases of explosion, for the working of the breech mechanism is by no means new, the latter system having been proposed and patented (certainly in a very crude and probably unworkable form) by (Sir) Henry Bessemer in 1854; but whatever might be discovered by a search in old patent and other records or in museums, there can be no doubt that (Sir) Hiram S. Maxim was the first to produce a finished automatic gun of practical value. His patents in connexion with this particular class of weapon date back to 1884, and his gun on the recoil system was, after extensive trials, adopted into the British army in 1889 and into the navy in 1892. It is very possible that Bessemer’s idea did not bear fruit earlier because the fouling left by the old forms of “black” or smoky powders was apt to clog the moving parts and to choke any small port. With modern smokeless powders this difficulty does not arise.

The Maxim gun, as will be seen from figs. 7 and 8, consists of two parts, the barrel casing (a) and breech casing (d), secured firmly together. The former (a), which is cylindrical in form, contains the barrel (b), and the water surrounding it

to keep down the very high temperature attained by rapid fire, and the steam tube (c), which by the action of a sliding valve allows of the escape of steam but not of water. The barrel has asbestos packings at its front and rear bearings in the casing, which allow of its sliding in recoil without the escape of water. The breech casing (d) is a rectangular oblong box, and contains the lock and firing mechanism. At its rear end it has handles (e) by which the gun is directed, and the thumb-piece (m) by which the trigger is actuated. Its top is closed by a lid, hinged at (i). At its front is a recess holding the feed-block (f) through which the belt of cartridges (g) is fed to the gun.

Attached to the rear of the barrel (b) on either side are two side plates (h), between which in guides O works the aggregation of parts D, F, J, K, L, P, T and V, which constitute the lock, and (in bearings) the crank axle E, crank E′, and connecting rod I (see figs. 7 to 11).

The connecting rod I joins the lock and crank, being attached to the side levers J of the former by means of the interrupted screw U; the latter enables the lock to be detached and removed.

The crank axle E extends through both sides of the breech casing (d), slots (k, fig. 7), allowing it a longitudinal movement of about an inch. To its left-hand end, outside the breech casing, is attached the fusee chain Y of the recoil spring X (see dotted lines in fig. 7), and to its right-hand end a bell trunk lever, B B′; the arm B, which terminates in a knob, being turned by the crank handle, the arm B′ working against the buffer stop C.

In figs. 8, 9 and 11 the breech is shown closed, and it will be noticed that the crank pin I’ is above the straight line joining the axis of the barrel, the striker T, and the crank axle E. As the crank is prevented from further movement upwards by the crank handle B taking against the check-lever G (fig. 7), it is clear that the pressure on discharge of the cartridge cannot cause the crank axle to rotate, and so open the breech as shown in figs. 10 and 12.

The withdrawal of the lock and opening of the breech are effected as follows: The total travel in recoil of the barrel is about one inch, but on discharge the barrel, the side plates and lock all recoil together for about a quarter of an inch without any disturbance of the locking as explained above, and by the time this short travel is completed the bullet has left the muzzle. The arm B′ of the crank handle then engages the buffer stop C and causes the crank axle E to rotate and the crank E′ to fall and so draw back the lock from, and open, the breech. At the same time the fusee chain Y is wound up round the left-hand end of the crank axle E and the spring X extended. In the meantime the knob of the buffer handle B swings over, and just as the lock reaches its rearmost position (as in figs. 10 and 12) strikes the flat buffer spring H, and, rebounding, assists the crank in revolving in the reverse direction; the spring X also contracts, and, unwinding the fusee chain, draws back the lock again and closes the breech, a fresh cartridge having been placed in the barrel as explained below.

The gun is fired by means of the trigger F, which is actuated by the projection (l) on the trigger bar (S), the latter being drawn back when the button (m) on the push lever (n) is pressed forwards. If, therefore, the button he kept permanently pressed, the projection (l) will always lie in the path of the trigger F just as the lock reaches its forward position and the breech is closed, and the gun will fire automatically, and continue to do so as long as there are cartridges in the belt.

The loading, extraction and ejection of the cartridges are effected as follows: The left-hand side-plate is extended forwards a little beyond the breech, and communicates the reciprocating motion of the barrel to a lever on the feed-block, which causes the cartridges in the belt to be fed forward one by one by a “step-by-step” pawl action, the cartridge which is next to be taken from the belt being arrested exactly above the breech, the ejector-tube Q being below in the same vertical plane.

The extractor D (see figs. 9 to 12) which performs the operations