Safetied demolition charge fuze

In a safetied demolition charge fuze of the kind that upon ignition actuation switches from a safe to an armed state and comprises a housing with head and tail ends;

• an arming lever hinged to said housing and engaging an arming slider slidable by the action of an activating spring from an engaging, safe position to a disengaging, armed position and retained in the safe position by said arming lever;
• a spring loaded firing pin;
• a safety lever retaining said spring loaded firing pin, which safety lever is retained by said arming slider in the safe position and swings in the armed state of the fuze out of engagement with said firing pin by the action of the spring of the latter when said safety lever becomes disengaged from said arming slider;
• a percussion primer assembly at the head end of said housing so positioned that when said safety lever swings out of engagement with the firing pin, the latter strikes said percussion primer;
• a pyrotechnic delay charge having a first end close to said primer assembly and a second end turned away therefrom, which delay charge is ignitable by said primer;
• a detonator ignitable by said pyrotechnic delay charge;
• and a booster charge ignitable by said detonator;
• the improvement by which:
• (i) said detonator is borne within a safe-and-arm slide mounted inside said housing intermediary the second end of said pyrotechnic delay charge and said booster charge, which detonator is slidable between a safe position in which the detonator is out of alignment with said pyrotechnic delay and booster charges, and an armed position in which it is in alignment with both the pyrotechnic delay and booster charges, which safe-and-arm slide is biased into the armed position and retained in the safe position;
• (ii) a retainer shaft is provided, associated with spring means by which it is shiftable from a safe position in which said safe-and-arm slide is retained in said safe position, and an armed position in which it clears said safe-and-arm slide whereby the latter is free to move into the armed position;
• (iii) a detent mechanism is provided for locking said retainer shaft in the safe position, which detent mechanism comprises a casing, a locking member mounted within said casing and engaging a recess in said retainer shaft;
• means responsive to the action of said spring means of said retainer shaft for pressing said locking member so as to push it away from said retainer shaft;
• heat sensitive means associated with said locking member which heat sensitive means resist below a present temperature the pressure exerted on said locking member and which soften upon raise of temperature by heat from said pyrotechnic delay charge whereby said locking member yields to the pressure exerted thereon and is pushed out of engagement with said retainer shaft whereby the latter is unlocked and moves by the action of the said associated spring means into the armed position thereby clearing said safe-and-arm slide whereby the latter is free to move into the armed position in which said pyrotechnic delay charge, detonator and booster charge are all aligned.