(a) Percussion if it acts on impact, producing a low order of explosion.
(b) Time when it acts in the air at a certain point of the trajectory.
(c) Combination if it is able to act in the air or upon impact.
(d) Detonating when it contains a fulminate which will bring about detonation upon impact.
The detonator may be separate or incorporated in the fuse. For the 75-mm gun and the 155-mm howitzer it forms a part of the fuze.
Many fuzes are armed on set-back. An exception to this is the long detonating fuse, MK 111, which is armed by the unrolling of a brass spiral holding together two half rings made of steel so fitted as to prevent the anvil and the head of the fuse from getting close together. The spiral unrolls when the rotational velocity of the projectile reaches a certain speed, thus drawing away the two steel rings and arming the fuse.
DETONATING FUZE—MARK-III.
DETONATING FUZE—MARK-V.