DATA:

BOMBS USED IN

FUNCTIONING

ARMED CONDITION

FUZES USED WITH

ARMING TIME

DIAMETER OF FUZE

LENGTH (w/booster)

SPINDLE LENGTH

MATERIAL

Three zinc alloy castings, top, middle, and base, held together by three long screws.

GENERAL:

The top section of the fuze is centrally threaded for the arming spindle, the middle section houses the clockwork and firing mechanism, and the base section is a simple flat casting added only to afford a means of screwing the plastic booster cup to the fuze. The fuze screws into the bomb with a left hand thread and is tightened with a spanner wrench which fits into the two spanner holes in the top of each fuze. Luting on the threads insures a tight, moisture-proof fit. Assembly of the fuzes in the bombs is done at the factory.

OPERATION:

The clockwork meachnism in the unarmed position is seen in Fig. 9. When the arming spindle has been withdrawn approximately .25 inch, the balance wheen release arm, pi-voted on the release arm cam, moves a limited distance until it is centered over the hole previously occupied by the arming spindle, Fig. 10. This action prevente the rein-sertion of the arming spindle and starts the mechanism in operation as the projection on the balance wheel release arm frees the balance wheel. With a maxium setting time of 30 minutes, the functioning is as follows:

(1) The timing gear, under the influence of its clock spring, rotates in a counter-clockwise direction. Near the end of its first revolutions, the stud on the timing gear engages the first slot of the setting plate and pulls the latter around with it a limited distance in a clockwise direchtion.

(2) Near the end of the timing gear's second revolution, the stud engages the se-cond slot in the setting plate, once again moving it a limited distance.

(3) Near the end of the third revolution, the stud on the timing gear engages the heel of the setting plate to move the latter clear of the timing gear. With the setting plate in this position, the setting plate cam presents its cutaway section to the release arm, thereby freeing the release arm. The release arm is forced past the setting plate by the spring-loaded striker bearing against the release arm cam. As the pivoted striker clears the release arm cam it is free to strike a counter-clockwise direction and fire the detonator, Fig. 11.

REMARKS:

Each complete rotation of the timing gear takes approximately 9 to 10 minutes and with the maxium setting of the setting plate a delay of 27 to 30 minutes will result. By varrying the initial position of the setting plate and/or timing gear at the factory, the fuze can be set to function for any desired time up to 30 minutes. This fuze is a copy of the German (67) Butterfly fuze.