Description
This is a Japanese Army mechanical impact tail fuze. it is used in 250 kg and 500 kg GP bombs. The fuze is brass except for a steel spring and striker. Its companion fuze is the A-4(a).
The upper portion of the body houses the arming vane assembly. The arming spindle is threaded at the lower end to screw into the striker which is located in the lower portion of the body. A locating screw causes the spindle to rotate with the arming vanes. Two locating screws keep the striker from rotating as the spindle is unscrewed. The striker is kept away from the primer by a spring. A grub screw holds the body screwed into the lower portion. Two holes are present for the U-shaped safety wire. Six spanner holes are located in the body. The standard Army gaine is surrounded by a booster.
Functioning
On release from the plane, the arming wire is withdrawn from the holes in the vanes and the latter rotate, unscrewing the spindle from the striker. The vanes will not fall free because they are held on by a locknut on the vane boss collar. On impact, the striker moves downward, and the firing pin enters the primer, overcoming the resistance of the spring.
Hazardous Components
Primer, Army gaine, booster
Physical Data
Length, overall - 5.9 in, 149.9 mm
Width, overall - 2.4 in, 61 mm
See Also
Nose, A-4(a), Type 92 for Large Bombs
Source(s)
OP 1667, Japanese Explosive Ordnance, Volume 1 (1946)
USNBD - Japanese Bombs & Fuzes (1944)
TM-E9-1984, Enemy Bombs and Fuzes, Section VII, Japanese Fuzes (1942)
