GB779937A - A selective firing device for land mines - Google Patents

Abstract

779,937. Land mines. ALSETEX SOC. ALSACIENNE D'ETUDES ET D'- EXPLOITATION. Oct. 5, 1955 [Oct. 6, 1954], No. 28382/55. Class 9 (2). A firing device for land mines comprises a body 1 and a cap 2 relative displacement of which is produced in successive stages by the passage of loads to effect operation of an igniter at a predetermined stage which is regulable at will. Within the body 1 is a partition, the part 10a having a dependinng portion bearing on a deformable sealing ring 3 to form a chamber communicating through a valve 6, 7 with a fluid reservoir 5. From the chamber 4 fluid can pass through a channel 9 and a valve 8 into the space between the partition and an elastic membrane 11, this space having communication with the reservoir 5 through narrow passages 12. Above the membrane 11 is an igniter 14, detonator 15 and a relay 16. A single load passing over the device causes relative displacement of the body 1 and cap 2 so that fluid passes from the reservoir 5 through the valve openings 6 and into the channel 9 with consequent deformation of the membrane 11. The fluid returns slowly to the reservoir through the channels 12 and the device returns to its initial state. If successive loads are applied, the fluid enters the channel 9 more rapidly than it can be returned by the channels 12 and the deformation of membrane 11 increases until a thrust is applied to the igniter 14 which causes firing of the mine. The detonator 15 may be inserted when the device is to be used, a plug 17 and packing 18 being used to close the detonator recess. The partition 10a may have a shearing groove 19, so that when a heavy pressure is applied to the device, e.g. when the mine is set in light soils, the partition ruptures at the first impact and operates the igniter immediately. The device may be made of non-magnetic materials such as ethyl-cellulose, styrenes, phenoplasts and aminoplasts. The fluid may be liquid or gaseous. In a modification, the elastic membrane 11 is replaced by a rigid partition which may have an annular weakening or be held by shear pins adapted to fracture at a given pressure. Alternatively, the partition may be free, the igniter being set to move at a given pressure on the partition. The firing device A is mounted in a mine, Fig. 3 filled with explosive B, the base of the mine being supported on a plate 23 by a flexible member 24.