Relic Inert WWI German Z.s.u.m.WM Fuse

Since 1914, the German Army pionneers were given 175mm middle minenwerfers and 245mm heavy minenwerfers. A specific fuze was existing for each of the two models.

The ‘ZmWM‘ fuze – ‘zünder für mitteler Wurf-Minen’ (‘fuze for middle mine launchers’) was the device dedicated to the 17cm mines. Realized in brass, it was based on :

• a graze action arming system in the fuze top section similar to the one of the ZsWM fuze, with a massive mobile graze pellet carrying the primer and secured by a single rod safety pin, and a static percussion pin secured by a creep spring,
• a two discs time system, the mobile lower ring being graduated from 7 to 21 seconds.
• a graze action percussion system in the fuze tail similar to the one of the ZsWM fuze, made with two opposite direction percussion pins on a transverse static bridge, and a cylindrical mobile graze pellet with two primers and two safety springs, secured by a jaws system blocked at rest by a gunpowder pellet and only able to open when it has burned.

the percussion mechanism of some models could be blocked with a screw marked ‘Vest’ and located on the lower fuze cone, for use with gaz shells. The fuze could also be covered by a flame-hiding hat in aluminium or thin steel plate for night time shots.

After 1915, the ZmWM fuze was adopted also for the heavy minenwerfers instead of the big ZsWM fuze, and was renamed ‘ZsumWM‘ – ‘zünder für schwerer und mitteler Wurf-Minen’ (‘fuze for heavy and middle mine launchers’). It was mounted on the projectiles of the :

• Middle Minenwerfers 17cm mWM 13 or a/A (175mm) – high explosive bombs, incendiary bombs and gaz bombs
• Middle Minenwerfers 17cm mWM 16 or n/A (175mm) – high explosive bombs, incendiary bombs and gaz bombs
• Smoothbore Minenwerfers (18cm Projector) (180mm) – gaz smooth bombs (blue cross)
• Heavy Minenwerfers 25cm sWM a/A (245mm) – elongated high explosive bombs, high explosive half-bombs and gaz half-bombs.
• Heavy Minenwerfers 25cm sWM 16 or n/A (245mm), elongated high explosive bombs