Schneider mechanical fuze-setter

Before the introduction of the quick-firing gun in France, the gunner usually had to set the fuzes by hand, using a hand key or wrench to turn the fuze head to the required setting. In 1897, thanks to the researches carried by cpt. Demangel starting from 1891, a mechanical fuze-setting for double acting time and percussion fuzes was adopted by the French Army, that later developed several different models of it, both for field and heavy guns (a detailed description of the working of the French debuchoir Mle. 1897 could be found at Forum pages 14-18). Soon the French artillery firms, like Schneider, were able to offer similar devices to the countries that bought their guns. These mechanical fuze-setters proved to be easy to handle and very effective, since assured a simpler and more accurate setting of the fuze. Usually it was carried on the caisson of the ammunition wagon.
Schneider double mechanical fuze-setter for field gun. It was composed by a box with two cylindrical casing e, containing the wreaths C1 and C2, provided with two little spring bolts v1 and v2 and included between the frame φ and the graduated cap g. On the inside the two wreaths were shaped according with the shape of the nose of the fuzed shell. They could turn around their axis, respectively acting on the handwheel v and rotating the crank m. The transmission was arranged so that the angular displacement had the same extent both on the right and on the left side, allowing the setting of two different fuzes at the same time. At first the shells were placed vertically in the casings, with the heads down. Acting on the handwheel v, the marks r of the wreath C1 were put in front of the division engraved on the cap g; the spring bolts v1 and v2 took the correct angular deviation and fell in the corresponding grooves of the fuze. Then rotating the crank m, they were engaged in the plugs (N° 20a in the Schneider fuze) screwed on the external surface of the fuze cap, and the bottom composition ring (N° 2) turned of the desired angle, adjusting both the fuzes at the same setting. The time of burst could be modify even at the last minute by means of the handwheel v.
Schneider single mechanical fuze-setter for heavy gun. The details of the mechanism were similar in many functional respects to the double fuze-setter described above, but it could set only one shell at a time. The spring bolts v1 and v2 were placed at the required angular distance turning the wreath C1 by means of the milled knob B, whose motion directed the plate π carrying in relief a spiral which was engaged in the toothed arc k, or disengaging by means of the ring A the spiral to bring by hand, through of the lug t, the mark r in front of the desired division. Then the shell was placed on the fuze-setter as above, and was adjusted at the desired set simply rotating the wreath C2 of one or two turns, by means of the crank M. The time of burst of the fuze could be modify by means of the knob B’, which shifted the mark r’ in front of the corrector K, setting the wreath C2. The fuze-setter was equipped with a special safety device, to block the rotation around the axis xy. The crank M was blocked by the toe of the safety latch λ, which entered in a groove cut in the casing e. So, to turn the wreath C2, it was necessary to press down the crank, which could pivot around the axis o (see the dotted line in the second picture below). After every turn, the spring ρ, acting under the pivoting point o’ safety latch, pulled up the latch, preventing to make another turn. SOURCE : CUREY. Charles Marie : “L’artillerie Schneider-Canet à l’Exposition universelle de 1900”. Revue d’artillerie : 59 (Octobre 1900 – Mars 1901), pp. 148-150 and 157-160.

Schneider single mechanical fuze-setter for heavy gun