Description
The Mechanical Impact Fuze M170 duplicates the AN-M120A1 in all respects except for the arming time, which is shortened to 1.5 (± 0.15) seconds in the M170.
The M120 and AN-M120 did not have the clockwork regulator, and had an arming time of 2.5 (±0.25) seconds; hence, attacks had to be made at higher levels. External appearance of all designs is the same.
This fuze replaced the AN-M104 in the parachute fragmentation bomb.
The M170 is designed to supplant the AN-M120A1 in all bombs receiving the AN-M120A1, except for the 120 pound Para. Frag. Bomb M86, which will continue to use the older fuze
Functioning
As the parachute opens, the arming wire is withdrawn from the arming pin, which is then ejected by the arming-pin spring. Ejection of the arming pin frees the arbor, a semicircular projection on the timing shaft, to be rotated by the clockwork mechanism. A regulator controls the oscillation of the clockwork governor, and is properly adjusted at the factory. The slider pin rides against the inside of the arbor under pressure of the slider spring. After the arbor has been rotated a full 160°, it clears the slider pin, allowing the slider to be forced across the fuze by the slider spring, lining up the detonator with the firing pin. A spring-loaded detent locks the slider in position. On impact, the striker head is forced in, driving the firing pin into the primer detonator and detonating the bomb.
Hazardous Components
No information about hazardous components.
See Also
Source(s)
MIL-HDBK-146, Fuze Catalog (1982)
TM 9-1385-51, Ammunition (Conventional) for Explosive Ordnance Disposal (1967)
OP 1664, Volume 2 - US Explosive Ordnance (1947)
USNBD - Bombs and Fuzes, Pyrotechnics (1945)
TM 9-1904, Ammunition Inspection Guide (1944)
