Use: 75-mm shrapnel, incendiary, and illuminating projectiles, 105-mm shrapnel and in-cendiary projectiles, and 150-mm shrapnel and illuminating projectiles.

Over-all length: 2 13/16 inches.

Maximum diameter: 2 5/8 inches.

Thread length: 1/2 inch.

Number of threads: 3, right-hand.

Construction: This fuze is made of brass. A central spindle and base section are of one piece. Three powder rings are fitted over the spindle and held in place by a nose cap which threads onto the top of the spindle. Housed in the nose cap is an aerial-burst pri-mer carrier seated in a metal cup. The base of this cup has one centrally located hole. The top of the sides are flanged and rest on a shoulder of the central spindle. A safety pin is fitted through the nose cap and the primer carrier. A partition in the hollow spindle contains a firing pin pointed on either end. Housed in the base of the spindle is a detent-held, movable impact primer carrier which is separated from the firing pin by a coiled spring. A base plate threads into the base section and contains a black-powder maga-zine. The top and lower powder time rings are keyed together and movable; the center ring is stationary. The rings are graduated form 0 to 36.6 seconds in increments of 1/5 second.

Operation: Before firing, the safety pin is removed and the time rings set. On setback, the aerial burst primer moves down onto the stationary firing pin, and the resulting flash ignites, through a flash channel, the upper time ring. The powder train leads through the time rings down to the black-powder magazine in the base of the fuze.

Centrifugal force causes the detents to move out, freeing the impact primer, and, if the projectile hits beofre the time setting has elapsed, the primer carrier moves against the spring onto the firing pin. The flash from the primer sets off the black-powder magazine.

Figure 333 – Type 5th-year Combination Powder Time and Impact Fuze.