Mks 32 and 40 Type (Obsolete)

Operation: When the round is fired, acceleration in the gun causes the three set-back switches to close. This action connects the battery to the electrical mechanism and initiates charging of the firing condenser through its high-resistance delay circuit. Si-multaneously, the set-back pin in the centrifugal clock moves back against its spring, freeing and starting the clock escapement mechanism. In the armed position, the set-back pin is locked by the locking spring.

Centrifugal force drives the clock through its permanent setting of 0.4 to 0.6 second, at which time the tripping lever moves over the spring-loaded arming pin. The arming pin moves forward, withdrawing from the interrupter cavity. This allows the interrupter pin to be moved outward by centrifugal force, thereby clearing the flash channel between the electric primer and the auxiliary detonating fuze, hitting the short-circuit plug, and breaking the short-circuit wire away from the electric primer leads.

Meanwhile, the firing condenser has been accumulating an electric charge. When the charge is sufficient to allow firing of the electric primer, normally 0.6 to 0.8 second in the dry-battery type fuze, the fuze is fully armed.

On approach to a target under the proper conditions, the reflected electromagnetic signal from the target causes the V.T. element to discharge the firing condenser through the electric primer. The blast from the primer operates the auxiliary detonating fuze, which in turn initiates detonation of the projectile.

Operation of the wet-energized fuzes of this type is identical, except that the elec-trolyte vial in the reserve energizer is broken by acceleration of the round, and centrifu-gal force distributes the electrolyte throughout the energizer. Charging of the firing con-denser is not begun when the set-back switches close, but must wait until the electro-lyte is uniformly distributed through the reserve energizer. This normally occurs 0.2 to 0.3 seconds after set-back, thereby delaying complete arming of the unit until 0.8 to 1.1 seconds after set-back.

Figure 95. V.T. Fuze Mks 32 and 40 Type