Anti-handling device

An anti-handling device is an attachment to or integral part of a landmine or other munition e.g. some fuze types found in general purpose air-dropped bombs, cluster bombs and sea mines. It is designed to prevent tampering. When the protected device is disturbed, it detonates, killing or injuring anyone within the blast area. There is a strong functional overlap of booby traps and anti-handling devices.

Anti-handling devices prevent the capture and reuse of the munition by enemy forces. They also hinder bomb disposal or demining operations, both directly and by deterrence, thereby creating a much more effective hazard or barrier.

Anti-handling devices greatly increase the danger of munitions to civilian populations in the areas in which they are used because their mechanisms are so easily triggered. An anti-tank mine with an anti-handling device fitted is almost guaranteed to detonate if it is lifted/overturned, because it is specifically designed to do so. Munitions fitted with anti-handling devices increase the difficulty and cost of post-conflict clearing operations, due to the inherent dangers of attempting to render them safe.

Not all munitions will have an anti-handling device. Perhaps one in ten antitank mines in a large defensive minefield will have boobytrap firing devices screwed into their secondary fuze wells. Even so, deminers and EOD personnel are forced to assume that all items they encounter may have been boobytrapped, and must therefore take extra precautions. This has the effect of significantly slowing down the clearance process.

Anti-handling mechanisms have been used in fuzes since at least 1940, in, for example, Luftwaffe's ZUS-40 anti-removal fuze which was used during the London Blitz and elsewhere. ZUS-40s were designed to fit underneath most Luftwaffe bomb fuzes. When a delayed-action bomb containing a ZUS-40 was dropped on a target, the impact when it hit the ground freed a ball-bearing inside the ZUS-40, thereby arming a spring-loaded firing pin. However, so long as the main bomb fuze remained inside its fuze well, the cocked firing pin in the ZUS-40 was prevented from springing forward. ZUS-40s were often fitted underneath a type 17 clockwork long delay fuze, which gave between 2 and 72 hours delayed detonation. Rendering safe a type 17 fuze was normally a simple and straightforward process i.e. unscrew the fuze locking ring, remove the fuze from its pocket in the side of the bomb and unscrew the gaine. However, fitting a ZUS-40 underneath a type 17 fuze made the render-safe process much more complicated and dangerous. Removing the main time-delay fuze more than 15 millimetres from its fuze pocket (without neutralising the anti-handling device underneath) automatically released the cocked firing pin inside the ZUS-40, which sprang forward to strike a large percussion cap, thereby causing detonation of the bomb and the death of anyone nearby. Because the ZUS-40 was designed to be concealed underneath a conventional bomb fuze, it was very difficult to know whether a particular bomb was fitted with an anti-handling device or not. In any case, many electrically fired German bomb fuzes already had a pendulum-based "trembler" switch which triggered detonation if the bomb was subjected to rough handling. Some German anti-handling fuzes were even more dangerous to EOD personnel, such as the type 50 and 50BY fuzes. These were normally fitted to 250/500 kg bombs and contained two mercury tilt switches which detected vertical or horizontal movement. The fuzes fully armed themselves approximately 30 seconds after hitting the ground. Subsequently, if the bomb was moved in any way, the mercury switch triggered detonation. To complicate matters still further, German bombs could have two separate fuze pockets fitted, with different fuze types screwed into each one. As a result, one bomb could incorporate two separate anti-handling devices working independently of each other e.g. a type 17 clockwork fuze with a ZUS-40 hidden underneath it screwed into one fuze pocket, and a type 50BY in the other. Even comparatively small air-dropped munitions could incorporate an anti-handling feature e.g. the type 70 fuze fitted to Butterfly bombs. However, fuzes with an integral anti-handling feature were not only found in air-dropped bombs. For example, the T.Mi.Z.43 fuze (dating from 1943) fitted to Teller mines automatically triggered detonation if (in an attempt to render the mine safe) the pressure plate was unscrewed. Although the designs of these anti-handling fuzes varied, all were specifically designed to kill bomb disposal personnel who had the task of rendering them safe.

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