BOOSTER EXTENDERS

34. BOOSTER-EXTENDERS are hydrostatically-operated devices which hold the booster charge away from the detonators until after the depth charges are submerged. When a booster-extender installed in a depth charge is in the safe position, the distance bet-ween the detonator and the booster charge is such that even if the detonator should explode accidentally, the booster and main explosive charges would not be detonated. When a booster-extender operates it moves the booster charge toward the pistol until the detonator is housed in an envelope in the end of the booster can. The end of the booster can then rests against the centering flange on the inner end of the pistol. These mechanism are designed to operate without adjustment at depths of 11 to 22 feet.

HOW THEY WORKS

35. When a depth charge is dropped from a release track, the knobbed safety fork on the booster-extender is stripped from the mechanism by a wiping plate on the track. If a charge is thrown from a projector, the plain safety fork is removed from the mechansim by hand before the projector is fired.

36. When the fork is pulled off the spindle, the bellows expands inward approximately ¼-inch, moving the spindle inward through the spindle bushing. This carries the reduced diameter of the outer portion of the spindle into the opening in the bushing so that there is space around the spindle through which water can enter the bellows. The spindle groove in which the locking balls rest is slightly elongated to provide for this initial motion of the spindle.

37. As water enters the bellows it forces the piston and spindle inward. Since the locking slide is locked to the spindle by the locking balls, the slide is carried inward with the spindle against the pressure of the extender spring. When the spindle moves far enough inward to carry the locking balls into the enlarged section of the spindle guide, the balls slip outward into the guide, freeing the spindle from the locking slide.

38. The only resistance to further inward motion of the piston is provided by the bellows. Since this is comparatively light, hydrostatic pressure now drives the piston inward until it carries the booster can against the centering flange on the depth charge pistol. At this point the detonator is housed in the envelope in the end of the booster can.

Drawings showing bellows expanding until detonator charge ready for firing