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Rockets Fuze

Type Classification:

Functioning:

Type Classification:

Standard, MSR 01786006.

Use:

Multi-Option Fuze M734 is designed to provide a selectable function capability for use with mortar cartridges. The four settings are PRX (Proximity), NSB (Near Surface Burst), IMP (Impact), and DLY (Delay).

Description:

Externally, the fuze consists of a head which may be rotated for option selection relative to a base which is rigidly screwed into the projectile. Markings PRX, NSB, IMP and DLY are on the head and the corresponding index line on the base. The two-piece fuze head consists of a plastic ogive containing the electronic assembly, rigidly attached to an aluminum ogive base containing the turbine alternator (T/A). The aluminum fuze base contains the safety and arming assembly (S&A).

Functioning:

Two distinct gun firing signals are required to arm the fuze: (1) Setback acceleration for the time duration of in-bore travel of the projectile and (2) travel through the air at projectile velocity for more than a minimum distance. Acceleration time is measured by a zigzag setback device in the S&A before disengaging from the S&A rotor. Air velocity-distance is measured by airflow through ports in the ogive which rotate the turbine of the T/A. A predetermined number of turns through a mechanical ear reduction unscrews a jackscrew lock from the S&A rotor. An interlock between zigzag setback device and gearing prevents spurious air turbine rotation (e.g., blowing hard into inlet hole). Once released by both locks, the spring-driven rotor turns 180 degrees to armed position, aligning explosive elements and connecting the electric detonator to the electronics.

The T/A is also an electrical generator which powers fuze electronics. Voltage (v) and frequency (f) of T/A output depend on velocity of the fuze through the air. The fuze electronics monitor voltage and frequency to provide a fuze electrical-function delay, additional to and greater than the mechanical arming delay.

Multi-Option Functioning:

The three function modes PRX, NSB and IMP are electrical and detonate the fuze through the electric, detonator in the S&A. DLY function is completely mechanical and is always available after arming, thereby serving as backup for all electrical functions. PRX provides airburst detonation (mean HOB 3 to 13 ft) for maximum fragmentation spread, NSB is a desensitized PRX (mean HOB 0 to 3 ft) for near-contact bursts. IMP is by closure of an electrical impact switch, airburst capability being suppressed. Fuze electronics automatically provide cascading functionability in descending order, should the set function not receive sufficient signal to trigger. Examples: Set PRX, M734 could also function NSB or IMP (and of course DLY); Set NSB, M734 could function IMP (and DLY). Only in DLY setting is there no backup.

Tabulated Data:

UNF-lA

Temperature Limits: Firing:

Lower limit-------------------------50°F (-45.5°C)

Storage:

Lower limit------------------------50°F (-45.5°C)

Packing:

Not a separate issued item, component of cartridge, 60 MM, HE M720.

Shipping and Storage Data:

DOT description ------------------- DETONATING FUZES-CLASS A EXPLOSIVES

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