DATA:

BOMBS USED IN

FUNCTIONING

ARMED CONDITION

FUZES USED WITH

ARMING TIME

DIAMETER OF FUZE

LENGTH (w/booster)

SPINDLE LENGTH

MATERIAL

Two zinc castings.

GENERAL:

The fuze consists of two castings, the top one having a center hole threaded for the arming spindle and the outer threads to screw the fuze into the bomb; the lower casting containing the timing, anti-disturbance and firing mechanisms, with its base in-ternally threaded for the tetryl booster cup. Assembly is held together by three long screws. On one side of the lower casting is a large hollow screw which holds the firing pin and the firing pin spring under compression. Diametrically opposite is another smaller screw retaining the primer detonator.

OPERATION:

When the arming spindle is withdrawn approximately .25 inch, the escape wheel spring and the timing gear are freed, and the fuze comences to arm. During the comp-lete operational circle, the fuze acts in three successive steps as follows:

(1) After about .5 second, during which time the timing gear rotates in a clockwise direction under the influence of the coiled drive spring, the entire mechanism is brought to a halt as the stud on the impact spring engages the stud under the timing gear and the fuze remains in this condition until impact.

(2) On impact, the force of inertia on the flat impact spring is sufficient to disengage the studs on the impact spring and the timing gear. The timing gear now continues its rotation for a period of approximately 5 seconds until the stud, seated in place above the timing gear, engages a small projection on the end of the anti-disturbance block. Here the timing gear is once again brought to a halt with the fuze in a fully armed posi-tion, as in Fig. 13. The fuze is now in an externally sensitive condition, since the anti-disturbance block is supported only by the delicate anti-disturbance block spring.

(3) Should the fuze now be subjected to handling, shock, or vibration, the projection on the anti-disturbance block and the stud above the timing gear would become disen-gaged. The timing gear can thus make its final run, this time until its blank segment permite it to slip by the small gear (with which it was previously engaged) with increas-ed momentum. During this last swift movement, the stud under the timing gear strikes the release arm stop, moving it away from the release arm, and the spring-loaded stri-ker can now rotate the release arm cam as the release arm is freed. The cam is forced around in a clockwise direction, permitting the striker to slip by and fire the detonator cap, initiating the booster, as in Fig. 14.

REMARKS:

There are no markings on the fuze to identify it, and when fitted into the bomb, it can not be distinguished from the M130 fuze. This fuze is so sensitive that the vibration caused by an aircraft propeller nearby may be sufficient to release the anti-disturbance block and fire the fuze. This fuze is copied from the German (70)B, Butterfly fuze.