DATA:

BOMBS USED IN

Mk 229

AN-Mk 230

FUNCTIONING

ARMED CONDITION

FUZES USED WITH

ARMING TIME

OVERALL LENGTH

MAX. BODY DIAMETER

VANE SPAN

MATERIAL

Steel, aluminum alloy, and brass.

GENERAL:

These two fuzes are identical except that the part of the Mk 229 fitting into the bomb body is 1.3" longer than the corresponding part of the AN-Mk 230; hence, the AN-Mk 230 cannot be used in bombs that take the Mk 229 fuze. The AN-Mk 230 fits into the M115 or M115A1 adapter booster, and can be used in the general purpose bombs taking that adapter booster for use against marine targets.

OPERATION:

The desired depth setting is accomplished by turning the depth setting knob and thereby compressing the depth spring the proper amount. If a functioning at 125 feet is desired, the spring would be compressed the maximum, consequently causing the water pressure to overcome the greater resistance of more tightly coiled springs. If a shallow water functioning is desired, the springs would be only partially compressed and the water pressure necessary to overcome the more loosely coiled springs would be consi-derably less. In setting, the depth adjusting sleeve is raised to the desired spring com-pression by means of a five-sided cam secured to the external depth setting knob, and resting under a projection of the depth adjusting sleeve.

On release from the plane, the arming wire is withdrawn and the vanes are free to rotate. This rotation is transmitted by the vane shaft thru a series of reduction gears to the arming shaft. The upper gear has one more tooth than the lower gear, and as the pinion gear rotates around the lower stationary gear, the upper gear is pushed around clockwise one tooth per revolution of the vanes. This rotation of the upper gear causes the arming screw to rotate clockwise, since the upper gear and arming spring are positively secured, and because of the right-handed threads on the screw, the de-tent retaining cup threads up on it. As the cup clears the two arming detents locking the depth spring stem nut, their springs force the detents out, freeing the depth spring stem and the piston. The fuze is hten armed. On impact with the water the inertia counterbalance prevent the firing assembly from moving down and prematurely firing the fuze because of the deceleration caused by impact. As the bomb submerges, water enters two ports in the outer body and through holes in the depth setting mechanism housing. Hydrostatic pressure acting on the sylphon bellows forces the hydrostatic piston downward, compressing the firing spring, until the retaining balls fall out into the widened portion of the piston. The firing plunger is then forced downward by the pres-sure of the compressed firing spring onto the fixed firing pin, setting off the explosive train.

REMARKS:

(1) The detonator consists of fulminate of mercury and tetryl pellets, and the boos-ter lead-in, relay pellets, and booster are tetrly.

(2) The "O" Ring Gasket has replaced the Garlock Gasket. In using the "O" Ring Gas-ket, a support ring (steel washer .120" thick) must be used to assure metal contact between the fuze and fuze seat liner, thereby preventing distortion of the fuze on im-pact.

DO NOT DISASSEMBLE THIS FUZE WITHOUT REINSERTING THE SAFETY PIN THROUGH THE LOWER FUZE BODY AND FIRING PLUNGER.