Description
This fuze is identical to the Bomb Fuze AN-Mk 219, except that it has been partially armed fifty turns of the arming vanes and a metal fork has been inserted between the vane carrier and the fuze body to take up the space left by the pre-arming process. This fork must be removed before launching the fuzed rocket. In addition, the pitch of the vanes has been increased to 10 degrees instead of the 18 degrees on the AN-Mk 219.
Functioning
There are two stages of arming. During the first stage, the upper gear is free to rotate and the lower gear, being attached to the hammer carrier locked by the inner sleeve, is held stationary. During the second stage, the hammer carrier has risen to clear the inner sleeve, and the lower gear is free to rotate, while the upper gear is held stationary, as it is attached to the arming shaft, which was threaded up until it locked against the shaft extension nut.
First stage: As the rocket is launched, the arming wire is withdrawn and the vanes are free to rotate. Through the system of reduction gears, the upper gear rotates to thread the arming shaft up until the head of the screw on 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 to free the lower gear.
Second stage: 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 forced inward. The shear wire in the arming shaft is cut as the upper part of the shaft telescopes 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 auxiliary booster lead-in, booster lead-in, booster, and main charge successively.
Hazardous Components
No information about hazardous components.
See Also
Source(s)
OP 1664, Volume 1 - US Explosive Ordnance (1947)
