The Frankford Arsenal Combination Fuze, 15 Seconds, Model 1894, for Shrapnel of Field-guns.
This is a time and percussion fuze ([Fig. 46]). It weighs 17½ oz. The time element is contained in the front part of the bronze body (a) of the fuze, and the percussion element in the rear part. The time-plunger (b) has five lugs (k) which hold the plunger in position above the firmly fixed steel firing-pin (c) after the safety-pin has been withdrawn; these lugs are broken by the shock of discharge. The safety-pin (j) passes through a hole in the upper part of the plunger, and it and the lugs are protected by the brass cap which is pierced to allow the insertion of the safety-pin.
Fig. 46.
By this arrangement the plunger and its lugs are entirely protected from any blow that may be received on the nose of the fuze. The priming composition is contained in the base of the plunger (at i), and is protected by a disk of tinfoil.
The compressed powder-ring (q) is held in a groove in the body of the fuze by a brass ring, and four holes (p) permit the flame from the composition (i) to ignite it.
The cone (d), made of an alloy, is held in place by a brass clamping-nut (h) and two brass pins (l). A lip (m) on the base of the cone fits into a corresponding groove in the fuze-body and prevents the premature ignition of the powder (o) in the fuze-chamber.
A groove in the cone contains the time-train (e), which communicates through a brass tube (n) with the powder in the fuze-chamber (o).
The brass cone-cover (f) is pierced with holes numbered from 1 to 15. The holes lie immediately over the time-train and correspond to seconds of graduation. The spaces between consecutive holes are sub-divided into six parts, and countersunk at the points of division so that the fuze may be cut to sixths of a second of burning.
A brass pin projects from the body of the fuze and fits into a slot in the cone-cover; it fixes the latter in position and, together with the brass cup on top, also serves to hold the cover in place.
The flame from the powder in the fuze-chamber communicates with the bursting-charge of the shell through the grooved surfaces of the primer, plunger-sleeve, and bottom closing-screw.
The opening into the fuze-chamber through which the charge is put is closed by the screw. A conical hole in the fuze-body immediately opposite this screw permits the insertion of a steel pin for the purpose of screwing the fuze into the shell.
The percussion element consists of a brass primer (t) having three vents through which the flame may pass from the composition to the powder in the fuze-chamber.
On the side towards the firing-pin the composition is covered first with a tinfoil cup and then with a copper restraining-disk, which is separated from it .04 of an inch both for safety and to prevent the firing-pin pressing against the composition during flight. On its opposite side the primer is covered with a tinfoil ring and a paper disk.
The bottom of the fuze is covered first by a paper and then by a tinfoil disk.
The primer, plunger-sleeve, and bottom closing-screw have their sides grooved longitudinally (r, r, r) to allow the flame from the powder in the fuze-chamber to pass to the bursting-charge of the projectile. With the exception of this difference in the plunger-sleeve the plunger is the same as the one in the Frankford Arsenal base percussion-fuze "C," model 1894.
TO USE THE TIME-FUZE.
Pierce the time-train cone at right angles to the axis and through the division in the cover corresponding to the desired number of seconds. Then remove the safety-pin before inserting the projectile in the bore of the piece.
A fuze-cutter is issued by the Ordnance Department for use with the fuze.