DATA:

BOMBS USED IN

FUNCTIONING

ARMED CONDITION

FUZES USED WITH

ARMING TIME

VANE SPAN

MAX. BODY DIAMETER

OVERALL LENGTH

MATERIAL

Steel, aluminum alloy, and brass parts.

GENERAL:

This fuze uses the "rotor system" of arming, and the operation of this system is the same in all the fuzes that use it: AN-Mk 219, Mk 221, Mk 223, and AN-Mk 228. This fuze will function on impact with water or denser medium, providing it has been dropped from sufficient altitude to arm.

OPERATION:

There are two stages of arming. During the first stage, the uper gear is free to ro-tate and the lower gear is held stationary. During the second stage, the lower gear is free to rotate and the upper gear is held stationary.

1st Stage: As the bomb is dropped the arming wire is withdrawn and the vanes be-gin to rotate in a clockwise direction. Since the idler is attached to the vane carrier and is in mesh with the upper and lower gears, when the vanes rotate the idler gear is caused to move about the upper and lower gears. The lower gear is attached to the hammer carrier and is locked because the banner carrier is resting down in the inner sleeve. Since the upper gear has one more tooth than the lower gear, the upper gear will rotate in a clockwise direction one tooth for every complete revolution of the idler gear. The upper gear is positively attached to the arming shaft, and in rotating threads the arming shaft, and in rotation threads the arming shaft up until the head of the screw on the end of the shaft locks against the shaft extension nut. A collar on the shaft lifts the hammer carrier and the entire arming assembly. Simultaneously with the locking of the arming shaft and the upper gear, the hammer carrier clears the inner sleeve, freeing the lower gear.

2nd Stage: The lower gear has one less tooth than the upper gear, hence as the pinion continues to revolve (now meshing with the teeth of the stationary upper gear) the lower gear and hammer carrier are rotated in a counter-clockwise direction. The aligning lug on the hammer carrier engages the firing pin carrier, lining up the firing pin extension with the firing pin. Further rotation causes the firing pin carrier to engage the detonator carrier, lining the firing pin up with the detonator. The hammer carrier, firing pin carrier, and detonator carrier continue to rotate through 180 degrees, until the lip on the detonator carrier engages the inner sleeve. Simultaneously, the spring-loaded detent in the striker snaps into a recess in the hammer carrier, thus locking the firing train components in an armed position. Since the upper and lower gears are now both locked, the two copper pins securing the lower gear to the hammer carrier are sheared and the vanes rotate freely. (If the air speed is less than 300 m.p.h., the air pressure will not be sufficient to shear the pins, and the vanes will merely cease rotating.)

The fuze is now fully armed. On impact, the entire upper assembly of the fuze is for-ced inward. The shear wire in the arming shaft is cut as the upper part of the shaft te-lescopes into the lower part and the shear wire through the firing pin is cut as the firing pin extension forces the firing pin into the detonator. The detonator sets off the auxil-liary booster lead-in, booster lead-in, booster, and main charge successively.

REMARKS:

The early Mark 219, Mods 2, 3, and 4 are identical to the AN-Mk 219. The different mods merely indicated the manufacturer of the fuze. This was important only in that slight differences in the manufacture prevented the interchange of parts made by dif-ferent manufacturers.

The internal parts are held in the fuze by a single master locking screw.