AN-M104 (Obsolescent) and M109 (Obsolete) (Mechanical Impact)

Bombs

Functioning

Armed condition

Fuzes used with

Arming time, seconds

Body diameter, inches

Over-all lenght, inches

4.4

General: These fuzes ate identical except for three minor differences: The M109 has an additional spring beneath the striker head, and a smaller striker disc; and its arming wire is removed from the arming pin when it is released from the plane. The AN-M104 arming wire is removed when parachute opens.

Operation: When the bomb is dropped and the parachute opens, the arming wire is pulled from the arming pin and the spring-loaded arming pin flies free. Ejection of the arming pin allows the spring-loaded delay firing pin to spring up against the delay primer (starting the pyrotechnic delay train) and permits the spring-loaded slider to move against the delayed arming plunger. After 2.5 seconds, the 326° pyrotechnic delay train has burned around completely and the body pellet of black powder is ignited. The body pellet ingites the delayed arming charge, which blows out the delayed arming plung and disc, thereby freeing the delayed arming plunger. The plunger is pushed out by the spring-loaded slider as it moves over and lines up under the firing pin. The firing pin is re-tained only by the weak firing-pin spring, and, on impact, the firing pin impinges on the primer in the slider.

Remarks: Since the fuze has a mushroom striker head and a sensitive firing pin, it is a semi-all-ways acting fuze and very sensitive if touched at any angle. If the mushroom head is flush with the fuze body and the delayed arming disc is out, then it is assumed that the fuze is in a fired condition and care should be taken not to lift the mushroom striker head away from the fuze body.

The AN-M104 has been replaced by the AN-M120A1; and the M109, by the AN-M110A1.

Figure 329. Nose Fuze AN-M104