HomeFUZES and IGNITERSYugoslavia

UMP-1 is a pull fuze designed for the tripwire initiation of mines and demolition blocks.
The spring-loaded striker is held by retaining balls engaged inside the tubular fuze body. The actuating rod, which is fitted with a ring, runs axially through the centre of the fuze and into the hollow striker; the grooved end of this rod holds the retaining balls out against the wall of the fuze body.

The stab-sensitive detonator assembly is bonded into the end of the fuze body to create a waterproof seal and prevent removal.
A safety pin runs radially through the other end of the fuze body and actuating rod, secured by thin lockwire.
The body of UMP-1 / UMP-1V has a male M10 × 1 thread fitted with a sealing O-ring, and is normally unpainted, with its designation stencilled in black.

Once the fuze has been positioned, the tripwire is attached to the ring on the end of the actuating rod.
The lockwire is removed or broken and the radial safety pin withdrawn to arm the fuze. At this point, the actuating rod is pulled against the fuze body (see diagram), blocking off the holes for the safety pin.
When the wire is tripped, the actuating rod is pulled from the centre of the tubular body, further compressing the striker spring. The retaining balls ride out of the groove in the actuating rod, and then collapse into the centre of the hollow striker as the rod is pulled away. This releases the striker, which is then driven into the detonator assembly by its spring.

The photos show the practice version (UMP-1V) which is identical to the live fuze.
Photos and info © Josip.