GB541624A - Improvements in military land mines - Google Patents

Abstract

541,624. Military land mines. CROWLEY, J. F. May 29, 1940, No. 9441. [Class 9 (ii)] An explosive land mine is constructed so that it is armed by the passage of one or more vehicles over or near it and is only exploded by the passage of a subsequent vehicle. In use the mines are laid in successive rows of which only the innermost row is set to explode on the first contact, the other rows being set to permit the passage of one or more vehicles, according to their position, before they can be exploded. The arming may be effected by the action of the weight of the passing vehicle or by acoustic or other dynamic waves generated by it. Fig. 1, shows a mine having a movable cover 1 carrying striking pins 12 co-operating with percussion caps 13. Initially a cam 8 on a shaft 5 co-operates with a stop 9 to prevent the striking pins from reaching the percussion caps when the cover is depressed, but the cam is turned step by step at each depression by a pawl 3 engaging a ratchet wheel 4 on the shaft 5 until it no longer obstructs the stop 9. The number of steps required is determined by the initial setting of the cam which is effected by turning the shaft 5 from outside the casing. In another form a diaphragm responsive to sound waves completes an electric circuit through a solenoid to move the cam one step, a delay action relay preventing a second energization until after the lapse of a suitable interval. As an alternative a mercury switch responsive to earth tremors may energize the solenoid. According to the Provisional Specification the magnetic mass of the tank may act upon a circuit in the mine to effect the arming operation.