Recoil

In gunnery, is the retrograde motion impre ed upon cannon by the discharge. of the charge in the bore, expanding with equal force in every direction, finds only two ways of escape (the muzzle and the vent); the pre ure upon these points will therefore cease while it will be proportionally increased upon the parts directly opposite, that is, the bottom of the bore and that portion directly opposite the vent, producing in the first case the recoil, and in the other, indirectly, the dipping of the muzzle. The distance of the recoil depends entirely upon the nature and inclination of the ground upon which the carriage stands, the situation of the trunnions, angle of elevation, comparative weight of the gun and carriage, and upon the strength of the charge. The recoil has no appreciable effect upon the flight of a projectile, the latter being expelled from the gun before it has recoiled a fraction of an inch. The recoil of heavy guns fired with large charges is a serious consideration in gunnery. The recoil must be checked in a comparatively short space, and yet checked too suddenly the shock destroys the carriage as well as platform. Various methods have been tried. The truck-wheels upon which the top carriage runs in and out of battery are provided with eccentrics, which are thrown out of gear to produce sliding friction,—but this alone is not sufficient in most cases. Counter-mortars are sometimes clamped on the cha is-rail against the carriage, but this is objectionable, as it tends to destroy the cha is. Friction-plates, with clamping attachments to the carriage between them, and extending full length of the cha is, have also been tried, but the buckling of the plates soon ruined them. This plan has been recently revived, and the buckling prevented by interposing india-rubber between the rear ends of the plates and the transom of the cha is. For the most approved methods, see Air-cylinders and Hydraulic Loading Apparatus .