Fecha de publicación: 23/11/1979 Fuente: WIPO "royal booby" The mine anti-lifting booby-trap prevents movement by the enemy while allowing safe laying. A chamber is rigidly fixed to the mine (36), and is covered on the sidewalls (38) with igniting material (40), which sets off the mine. A solid ball (30), resting on a concave seat (28) in the chamber and initially held there by contact with one of the chamber walls ignites the pyrotechnic material. A time-lag mechanism allows the seat and the wall to be moved apart, so that the ball will roll against the igniting material and set the mine off if disturbed.