Patent Publication Number: US-4926752-A

Title: Safety fuze for a hand grenade

Description:
BACKGROUND OF THE INVENTION 
     The present is directed to the field of grenades, and more specifically to a safety fuze for use with hand grenades. 
     The hand grenade presently in use by the U.S. Department of Defense is the M2l3, shown in FIG. 11 and U.S. Pat. No. 2,562,928 to Lewis. The hand grenade fuze 100&#39; incorporates a number of features standard in hand grenades and similar, hand thrown, fuze-activated devices. For example, a pull ring assembly 700&#39; is inserted through the lever 600&#39;, through apertures in the fuze body 100&#39;, over the striker assembly 500&#39; to restrain the striker assembly 500&#39; in the safe position. Also, a safety clip 800&#39; is fastened around the lever 600&#39; and an extension 232&#39; of the fuze body 200&#39; to prevent accidental, premature release of the lever 600&#39; and the striker assembly 500&#39; if the pull ring assembly 700&#39; was accidentally removed. 
     However, in military situations when silence is of the utmost importance, the user frequently employs the unauthorized, unsafe, procedure of removing the safety clip 800&#39; to avoid detection by the enemy given by the distinctive sound from its removal, or the noise it produces upon impacting objects after being discarded. Also, because of the short length of the striker assembly 500&#39;, if the lever 600&#39; is unknowingly released even a slight amount after the pull ring assembly 700&#39; is removed, the striker assembly 500&#39; will be allowed to rotate and the striker 530&#39; will hit the primer 320&#39;, initiating the firing sequence. As this can occur without the knowledge of the user, the grenade can function while still in the user&#39;s hand or attached to an article of clothing. 
     Most fuze assemblies for hand grenades and the like employ lever and striker assemblies similar to those of the M213. Examples of such assemblies are disclosed in U.S. Pat. No. 2,042,461 to Gibson et al.; U.S. Pat. No. 2,421,672 to Short; U.S. Pat. No. 2,911,9l3 to Suden; and U.S. Pat. No. 4,513,667 to Caruso. 
     Another safety problem encountered with the M2l3 is associated with the firing train assembly, i.e., the primer assembly, the delay charge/cavity, and the detonator assembly. In the M213, the detonator charge is in direct fluid communication with the delay charge/cavity in the fuze body stem, and the delay charge/cavity is in direct fluid communication with the primer assembly. An insufficient amount of delay charge can cause a grenade to function, after the firing train has been initiated, in a shorter time than that required of complete delay charge. Also, the absence of any delay charge in the delay cavity can cause an instantaneous functioning of the grenade after the firing train has been initiated. Also, a crack or cracks, or porosity having fluid communication between the interior stem cavity and the outer stem wall of the fuze body, can permit hot gasses to be in like fluid communication with the interior of the detonator assembly. Also, the through fluid communication within the components of the firing train can cause deterioration of the explosive or pyrotechnic components, shortening shelf life and endangering the user who is depending on reliable performance of the device. 
     Other fuzes for hand grenades employ primer, delay, and detonator assemblies similar to those of the M2l3, as shown by U.S. Pat. No. 4,383,470 to Assman. 
     It is the solution of these and other problems to which the present invention is directed. 
     SUMMARY OF THE INVENTION 
     Therefore, it is the primary object of this invention to provide a safety fuze for a hand grenade in which the initiator lever assembly o striker cannot be unknowingly released. 
     It is still another object of this invention to provide the user with safety against instantaneously fired hand grenades. 
     It is also another object of this invention to provide the user with safety against critically early detonation of the hand grenades. 
     It is still another object of this invention to prevent premature detonation of the grenade from hot gasses entering the detonator assembly through cracks or porosity. 
     It is still another object of this invention to ensure adequate ignition of the pyrotechnic charges. 
     It is still another object of this invention to provide a safety fuze for a hand grenade that will prevent the internal migration of moisture, vapors, and other foreign matter, and entry or escape of same from or to the atmosphere. 
     These and other objects of the invention are achieved by the provision of a safety fuze for a hand grenade comprising a fuze body, a delay case assembly, a primer assembly, a detonator assembly, an initiator lever assembly, a cover assembly, and a pull ring assembly. The fuze body has a head, a stem, and a central portion intermediate the fuze body head and stem, and a bore extending longitudinally therethrough. The delay case assembly comprises a delay case matingly received in the bore and having a primer portion adjacent the top and a delay portion adjacent the bottom, and a sealant separating the primer portion from the delay portion. A primer holder, a primer and a primer booster charge comprising the primer assembly are positioned in the primer portion. A penetration charge is positioned at the bottom of the delay case, a delay charge is positioned above the penetration charge, and an ignition charge is positioned above the delay charge. An air gap separates the primer assembly from the ignition charge. 
     The detonator assembly comprises a detonator case matingly receiving the fuze body stem at the top thereof and being in sealing engagement with raised crimp surfaces on the fuze body, and having an explosive detonator charge positioned at the bottom thereof. A gap is provided between the fuze body stem bottom and the explosive charge. 
     The initiator lever assembly is mounted on the fuze body and is rotatable between an unprimed position and a primed position. It comprises an elongated initiator lever, mounting means for mounting the proximal end of the initiator lever to the fuze body head adjacent the fuze body top for rotation about an axis perpendicular to the plane of symmetry of the initiator lever; biasing means for biasing the initiator lever in its primed position, and a firing pin formed integrally with the initiator lever, the firing pin being positioned on the initiator lever to engage the primer when the initiator lever assembly is in its primed position. The initiator lever has such a length that in its primed position, its distal end extends forwardly of the front wall of the fuze body head. 
     The cover assembly covers the top and back of the fuze body head and includes a pair of opposed pin-receiving apertures in registration with apertures in the side walls of the fuze body head. 
     The pull ring assembly has an elongated retaining pin adapted to be inserted through the apertures in the cover assembly and the side walls of the fuze body head. The retaining pin retains the initiator lever in its unprimed position when inserted through the apertures. 
     In one aspect of the invention, the initiator lever is longer than and extends below the cover assembly and defines a handle to be restrained while holding and throwing the grenade. 
     In another aspect of the invention, the cover assembly is longer than and extends below the striker assembly and defines a handle to be restrained while holding and throwing the grenade. 
     In still another aspect of the invention, a safety latch is mounted on the cover assembly. The safety latch is movable between a first position for retaining the initiator lever in its unprimed position by engaging the apertures in the side walls of the fuze body head and a second position for permitting movement of the initiator lever into its primed position. 
     A better understanding of the disclosed embodiments of the invention will be achieved when the accompanying detailed description is considered in conjunction with the appended drawings, in which like reference numerals are used for the same parts as illustrated in the different figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a first embodiment of the safety fuze of the invention; 
     FIG. 2 is a perspective view of a second embodiment of the safety fuze of the invention; 
     FIG. 3 is a cross-sectional view of the safety fuze of FIG. 1, taken along line 3--3 of FIG. 1; 
     FIG. 4 is a cross-sectional view of the safety fuze of FIG. 2, taken along line 4--4 of FIG. 2; 
     FIG. 5a is a partial perspective view with parts broken away, showing the safety latch of the safety fuze of FIG. 2 in its first, locked position; 
     FIG. 5b is a partial perspective view with parts broken away, showing the safety latch of the safety fuze of FIG. 2 in its second, unlocked position; 
     FIG. 6 is an exploded perspective view of the safety fuze of FIG. 1; 
     FIG. 6a is a perspective view of an alternate embodiment of the initiator lever assembly for the safety fuze of FIG. 1; 
     FIG. 7 is an exploded perspective view of the safety fuze of FIG. 2; 
     FIG. 8 is a perspective view of a third embodiment of the safety fuze of the invention; 
     FIG. 9 is a cross-sectional view of the safety fuze of FIG. 8, taken along line 9--9 of FIG. 8; 
     FIG. 10 is an enlarged cross-sectional view of the primer assembly of the safety fuze of FIGS. 3, 4, and 9; and 
     FIG. 11 is a cross-sectional view of the prior art M213 fuse for a hand grenade. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIGS. 2, 4, 5a, 5b, 7, and 10, there is shown a first embodiment of a safety fuze 100a for a hand grenade G. Fuze 100a comprises a fuze body 200a having a head 202a, a stem 204, and a central portion 206 intermediate head 202a and stem 204. Central portion 206 includes external threads 210 for engaging mating internal threads T at the top of grenade G. 
     Stem 204 adjacent central portion 206 is provided with raised upper and lower annular lips 212 and 214, for a purpose to be described hereinafter. Lips 212 and 213 are formed as part of the die cast procedure for fuze body 200a. Lower lip 214 has a slightly smaller diameter than upper lip 212. 
     Body 200a can be cast or molded as can bodies 200b and 200c described hereinafter. 
     Head 202a has a pair of opposed side walls 220a of substantially right trapezoidal profile, a front wall 222a, a back wall 224a opposite front wall 222a and inset from the back edges of side walls 220a, a top wall 226a insert from the top edges of side walls 220a, and a bottom wall 228a opposite top wall 226a. Side walls 220a include a pair of opposed, parallel extensions 230a extending downwardly from bottom wall 228a. Side walls 220a also include an upper pair of opposed circular apertures 240a adjacent their back, upper corners, and a lower pair of opposed elongated slots 224a space downwardly from upper circular apertures 240a and extending into the extensions 230a, all for a purpose to be described hereinafter. Front wall 222a includes a pair of hinge lugs 250a extending from the top thereof, also for a purpose to be described hereinafter. 
     A cylindrical bore 260 extends longitudinal through fuze body 200a. Cylindrical bore 260 has a top portion 262 terminating at an opening 264 in top wall 226a and a bottom portion 266 terminating at a closure 268 at the bottom of stem 204. 
     A delay case assembly 300 is matingly received in bore 260 and comprises a delay case 302 having atop 304 and a closed bottom 306, a primer portion 310 adjacent top 304, and a delay portion 312 adjacent bottom 306. Delay portion 312 is recessed inwardly from primer portion 310, primer portion 310 being matingly received in top portion 262 of bore 260, and delay portion 312 being matingly received in bottom portion 266 of bore 260. 
     Primer portion 310 of delay case assembly 300 houses a primer assembly 318 comprising a primer 320, a primer booster charge 322 positioned below primer 320, and a primer holder 324 rigidly holding primer 320 and primer booster charge 322 in primer portion 310, a penetration charge 330 positioned at bottom 306 of delay case 302, a delay charge 332 positioned immediately above penetration charge 330, and an ignition charge 334 positioned immediately above delay charge 332, and an air gap 340 separating primer assembly 318 from ignition charge 334. Delay case 302 and fuze body stem 204 are both closed at the bottom to prevent the flash from primer 320, when initiated, from penetrating delay case 302 and fuze body 204 and to provide sealed, double-walled protection between the pyrotechnic charges and the detonator case discussed hereinafter. 
     As primer 320 is a low output primer, for which there may be improper ignition, primer booster charge 322 is provided to enhance the output of primer 320. 
     Primer holder 324 is crimped to retain primer 320 in place and primer portion 310 is crimped at top 304 of delay case 302 to retain primer holder 324 in primer portion 310. The crimped areas are coated with a moisture-proofing sealant such as phenolformaldehyde varnish, type III, grade A or B, Spec. MIL-V-13750. A sealant 350 such as nitrocellulose is applied to the bottom of primer holder 324 to bond primer booster charge 322 in place and to provide a positive seal between primer portion 310, primer holder 324 and delay portion 312. 
     Penetration charge 330, delay charge 332, and ignition charge 334 are all mixtures which are gasless or produce low pressure hot gases, so that they can be sealed within delay case 302. Air gap 340 provides expansion space for those gases. 
     Pyrotechnic formulations such as the following can be used. Ignition charge 334 weighs approximately 100 mg and has a composition by weight of 65 %±5 % zirconium, MIL-Z-399, type 2, class 2; 25 %±3% iron oxide, TT-P-375, type 1 or 2; 10 %±2 % diatomaceous earth having the following characteristics: 0.4 % loss of weight on ignition, 90 % minimum silica, and 99 % minimum granulation passing through a 325 mesh; and 0.5 % maximum binder. Delay charge 332 weighs approximately 1200 mg and has a composition by weight of 49 % tungsten MIL-T-48140, amend. I; 5% potassium perchlorate, MIL-P-217, grade A, class 4; 41 % barium chromate, MIL-B-550, grade A; and 5 % diatomaceous earth having the following characteristics: 0.4 % loss of weight on ignition, 90 % minimum silica, and 99 % minimum granulation passing through a  325 mesh; and 0.5 % maximum binder. Penetration charge 330 weighs approximately 100 mg and has a composition by weight of 75 %±5 % iron oxide, TT-P-375, type 1 or 2; 25 %±5 % magnesium, MIL-M-382, type 1, grade A, granulation 12; 0.5 % maximum binder. The binder can be omitted from ignition charge 334 and penetration charge 330, and the proportions of ingredients in delay charge 332 can be varied in a known manner to obtain the desired burning rate without jeopardizing the safety features herein described. 
     The charges are assembled in the following manner. Penetration charge 330 is inserted into bottom 306 of delay case 302 with a load of 20,000 to 40,000 lb./sq.in. for a pre-established dwell period of 3.0 sec. ±0.5 sec. Three increments of delay charge 332 are then pressed into delay case 302 directly on top of penetration charge 330 with a load of approximately 40,000 lb./sq.in. for a pre-established dwell period of 3.0 sec. ±0.5 sec. Finally, ignition charge 334 is pressed into delay case 302 directly on top of delay charge 332 with a load of approximately 40,000 lb./sq.in. for a pre-established dwell period of 3.0 sec. ±0.5 sec. 
     When ignited, penetration charge 330 will burn through bottom 306 of delay case 302 and closure 268 of bore 260. 
     The above-disclosed mixtures used for penetration, delay, and ignition charges 330, 332, and 334 generate lower hot gas pressures than the zirconium-nickel mixes currently in use in the prior art devices. Such lower hot gas pressures are desirable, in that they produce uniform burning rates and have proven long shelf life characteristics, in contrast to the zirconium-nickel mixes which decay significantly during storage, tending to increase delay times and to produce occasional duds. The higher gas pressures in the prior art devices can result in the gasses being forced through porous or cracked delay cavity walls into the detonator. 
     Stem 204 of fuze body 200a is matingly received in a detonator assembly 400. Detonator assembly 400 comprises a detonator case 402 having an open top 404 and a closed bottom (not shown), a receiving portion 410 adjacent top 404, and a detonator portion 412 adjacent the bottom. Receiving portion 410 matingly receives stem 204 of fuze body 200a. Detonator case 402 is crimped around lips 212 and 214 of fuze body stem 204 at 420 in a known manner to positively seal the interior of detonator case 402 against the entry or escape of moisture, vapors or other foreign matter and to provide an interference fit of detonator case 402 with fuze body stem 204. The difference in the diameters of lips 212 and 214 permits detonator case 402 to be stretched over lips 212 and 214. 
     The raised crimp surfaces 420 provide a positive sealing engagement between detonator case 402 and fuze body stem 204, while lips 212 and 214 increase the strength of fuze body stem 204 in the crimp area. This provides a substantial advantage over the crimp grooves in the fuze design of the prior art, which tend to reduce strength in the crimp area, provide an inferior seal, and invite cracks from the crimping operation at assembly. 
     Detonator assembly 400 further comprises an explosive charge 430 positioned in detonator portion 412 below stem 204 of fuze body 200a to define an air gap 440. The explosive charge is identical to that used in the current M2l3 hand grenade fuze. 
     An initiator lever assembly 500a is mounted to fuze body 200a and rotatable between an unprimed position and a primed position. Initiator lever assembly 500a comprises an initiator lever 502a elongated to define a handle to be restrained while holding and throwing the grenade G and having a longitudinal plane of symmetry, a distal end 504a, and a proximal end 506a. Initiator lever 502a is substantially planar adjacent proximal end 506a and curved adjacent distal initiator levers end 504a. Initiator lever 502a can be cast molded, or stamped as can 502b and 502c described hereinafter. 
     A pair of opposed ears 510 extend from proximal end 506a of initiator lever 502a parallel to the plane of symmetry. Ears 510 include a pair of opposed circular apertures 512. Proximal end 506a of initiator lever 502a is positioned between side walls 220a of fuze body 200a with apertures 512 in ears 510 in registration with upper apertures 240a in side walls 220a. A pin 520 is inserted through apertures 512 and apertures 240a, allowing initiator lever 502a to rotate between a first position corresponding to the unprimed position of initiator lever assembly 500a and a second position corresponding to primed position of initiator lever assembly 500a. 
     A firing pin 530 is formed integrally with initiator lever 502a, firing pin 530 being positioned on initiator lever 502a to engage primer 320 when initiator lever 502a is in its second position and initiator lever assembly 502a is in its primed position. A coil spring 540 is mounted around pin 520, one end 542 of spring 540 extending outwardly and engaging initiator lever 502a and the other end 544 bearing against back wall 224a of fuze body head 204a to bias initiator lever 502a in its second position. Coil spring 540 is made from high tensile strength wire, such as rocket wire, available through the National Standard Company Niles, Michigan, to withstand long periods of shelf life without reducing the reliability of its functioning capability. 
     Primer 320 is protected by a cover assembly 600a, which also bears against and in part covers initiator lever assembly 500a in its unprimed position. Cover assembly 600a comprises a cover piece 602a having the same longitudinal plane of symmetry as initiator lever 502a and having a top portion 604a covering the top of fuze body head 202a, a bottom portion 606a covering the back edges of side walls 220a, a lower surface 608a facing fuze body head 202a, and an upper surface 610a opposite lower surface 608a. Top portion 604a includes at its front edge a hinge clasp 620a that extends over and engages hinge lugs 250a, so that cover assembly 600a can be rotated by the user upwardly and forward of hinge lugs 250a to permit initiator lever assembly 500a to be released from its unprimed position. Bottom portion 606a includes a pair of side extensions 630a extending substantially perpendicular to lower and upper surfaces 608a and 610a. Side extensions 630a include a pair of opposed circular apertures 632a in registration with the upper ends of elongated slots 244a in side walls 220a. 
     A rotatable safety latch 640 is mounted on bottom portion 606a of cover piece 602a for retaining initiator lever 502a in its unprimed position. Safety latch 640 comprises a pair of oppositely extending lugs 642 mounted below lower surface 608a of bottom portion 606a of cover piece 602a for engaging elongated slots 244a, and a dial 644 mounted above upper surface 610a of bottom portion 606a. Lugs 642 and dial 644 are operatively connected via a pin 646 extending through bottom portion 606a for rotation about the longitudinal axis of pin 646 between a locked position and an unlocked position. 
     Dial 644 is provided with detent means such as a ball 650 and a spring 652 positioned in an aperture 654 for locking safety latch 640 in place in one of three positions, as by engaging dimples 660a in cover piece 602a. The three positions are a central safety position, in which lugs 642 are locked in slots 244a, and two armed positions, one to the left and one to the right of the safety position, in which lugs 642 are free of slots 244a. The three positions can be denoted by marks such as the letters &#34;S&#34; for &#34;safe&#34; and &#34;A&#34; for &#34;armed&#34; embossed or otherwise permanently marked on the surface of cover piece 602a. The use of left and right armed positions enables safety latch 640 to be easily used by both left and right handed users. 
     Initiator lever 502a is further retained in its unprimed position by a pull ring assembly 700. Pull ring assembly 700 comprises an elongated cotter pin 702 or the like adapted to be inserted through the upper ends of lower elongated slots 244a in side walls 220a and circular apertures 632a in cover assembly 600a and a pull ring 704 for pulling cotter pin 702 out of slots 244a and apertures 632a. When cotter pin 702 is in place, it further blocks movement of lugs 642 of safety latch 640, thus acting as a lock against accidental movement of safety latch 640. 
     In operation, to prepare grenade G to be thrown, pull ring assembly 700 is removed from safety fuze 100a by pulling on pull ring 704. Once cotter pin 702 has been removed from apertures 632a and slots 244a, safety latch 640 is rotated to disengage lugs 642 from slots 244a. All elements holding cover piece 602a in place are now removed and grenade G is prepared to be thrown. If the user reverses his decision to throw the grenade, he can easily reassemble cover assembly 600 and make it safe again. Otherwise, cover piece 602a is removed. 
     Upon release from the user&#39;s hand, spring 540 urges initiator lever 502a of initiator lever assembly 500a into its primed position. When initiator lever 502a reaches its primed position, firing pin 530 strikes against primer 320, causing it to ignite primer booster charge 322 and ignition charge 334. Ignition charge 334 ignites delay charge 332, which burn will burn for a desired period of time depending in a known manner on its length and composition. Delay charge 332 in turn ignites penetration charge 330, which burns through the closed bottom 306 of delay case 300 and the closed bottom 268 of fuze body stem 204 to ignite explosive charge 430 in detonator assembly 400. 
     Referring now to FIGS. 1, 3, 6, and 10, there is shown a second embodiment of a grenade fuze 100b for a hand grenade G. Fuze 100b comprises a fuze body 200b of substantially conventional construction having a head 202b, a stem 204, and a central portion 206 intermediate head 202b and stem 204. Central portion 206 and stem 204 of fuze body 200b are identical to those of fuze body 200a of fuze 100a. A cylindrical bore 260 identical to cylindrical bore 260 of fuze 100a extends longitudinally through fuze body 200b. A delay case assembly 300 identical to delay case assembly 300 of fuze 100a is inserted in bore 260. 
     Head 202b is similar to head 202&#39; of the M213 hand grenade fuze and has a pair of opposed side walls 220b of substantially right trapezoidal profile, a front wall 222b, a back wall 224b opposite front wall 222b and inset from the back edges of side walls 220b, a top wall 226b inset from the top edges of front wall 222b and side walls 220b, and a bottom wall 228b opposite top wall 226b. Side walls 220b include an upper pair of opposed circular apertures 240b adjacent their back, upper corners and a lower pair of opposed circular apertures 242b spaced downwardly from upper circular apertures 240b, both for a purpose to be described hereinafter. Front wall 222b includes a hinge pin 250b extending from the top thereof, also for a purpose to be described hereinafter. Bottom wall 228b includes a short transverse extension 232b extending downwardly from the back thereof, extension 232b  having a groove 234b formed therein for a purpose also to be described hereinafter. 
     Striker lever assembly 500b is mounted to fuze body 200b and rotatable between an unprimed position and a primed position. Striker lever assembly 500b comprises an striker lever 502b elongated so that in its primed position, distal end 504b extends forwardly of front wall 222b of fuze body head 202b. As shown in FIG. 3, striker lever 502b extends to a point between the bottom of central portion 206 of fuze body 200b and the bottom of stem 204 of fuze body 200b. It is thus substantially longer than the striker 502&#39; of the M213 fuze. 
     Striker lever 502b is substantially planar and has a longitudinal plane of symmetry, a distal end 504b, and a proximal end 506b. Proximal end 506b of striker lever 502b is positioned at the top of fuze body 200b between side walls 220b and is rotatable between a first position corresponding to the unprimed position of striker lever assembly 500b and a second position corresponding to the primed position of striker lever assembly 500b. A pair of opposed ears 510 extend from proximal end 506b of striker lever 502b parallel to the plane of symmetry. Ears 510 include a pair of opposed circular apertures 512. Striker lever 502b is mounted to fuze body 200b in the same manner as initiator lever 502a is mounted to fuze body 200a, by means of a pin 520 inserted through apertures 512 and apertures 540, and a coil spring 540 mounted around pin 520. A firing pin 530 is formed integrally or separately with striker lever 502b, firing pin 530 being positioned on striker lever 502b to engage primer 320 when striker lever 502b is in its second position and striker lever assembly 500b is in its primed position. 
     In an alternate embodiment, shown in FIG. 6a,striker lever assembly 500b&#39; has a contoured, compressed S-shaped profile. A pair of opposed tabs 514b&#39; extend integrally outwardly from the distal end 504b&#39; to form a T with striker lever 502b&#39;. Clenching bottom portion 606b of cover lever assembly 600b and tabs 514b&#39; simultaneously provides a safety applicable to both left- and right-handed users that necessitates the deliberate release of both in order to initiate the firing sequence. 
     Primer 320 is protected by a cover lever assembly 600b, which also covers striker lever assembly 500b and acts as a handle to be restrained while holding and throwing grenade G. Cover lever assembly 600b is substantially identical to a conventional cover assembly 600&#39; for an M213 grenade fuze and comprises a cover piece 602b having the same longitudinal plane of symmetry as striker lever 502b and having a top portion 604b covering the top of fuze body head 202b, a bottom portion 606b covering the back edges of side walls 220b and extension 232b and extending below the bottom of detonator assembly 400, a lower surface 608b facing fuze body head 202b and extension 232b, and an upper surface 610b opposite lower surface 608b. Top portion 604b includes at its front edge a pair of parallel, spaced-apart hooks 620b for engaging hinge pin 250b, so that cover lever assembly 600b can rotate upwardly around hinge pin 250b when striker lever assembly 500b and cover lever assembly 600b are released from its unprimed position. Bottom portion 606b includes a pair of side extensions 630b which are approximately parallel to the plane of symmetry and include a pair of opposed circular apertures 632b in registration with lower circular apertures 242b in side walls 220b of fuze body 200b. 
     Striker lever 502b is retained in its unprimed position by a pull ring assembly 700 identical to pull ring assembly 700 of safety fuze 100a. Cotter pin 702 is inserted through circular apertures 632b in side extensions 630b and lower circular apertures 242b in side walls 220b. 
     Striker lever 502b is further retained in its unprimed position by a conventional safety clip 800. Clip 800 includes a resilient, J-shaped hook portion 802, the short arm 804 of which engages groove 234b and the long arm 806 of which bears against cover lever assembly 600b to hold cover lever assembly 600b against the back edges of side walls 220b. Clip 800 also includes a handle portion 808 attached to the long arm 806 of hook portion 802, by which clip 800 can be grasped and removed. 
     In operation, to prepare grenade G to be thrown, pull ring assembly 700 is removed from grenade fuze 100b by pulling on pull ring 704 to remove cotter pin 702, and safety clip 800 is removed from grenade fuze 100b by pulling on handle portion 808 to disengage hook portion 802 from groove 234b. Spring 540 is then free to urge striker lever 502b into its primed position. 
     Referring now to FIGS. 8-10, there is shown a third embodiment of a safety fuze 100c for a hand grenade G. Fuze 100c comprises a fuze body 200c having a head 202c, a stem 204, and a central portion 206. Central portion 206 and stem 204 of fuze body 200c are identical to those of fuze bodies 200a and 200b of fuzes 100a and 100b. A cylindrical bore 260 identical to cylindrical bore 260 of fuzes 100a and 100b extends longitudinally through fuze body 200c. A delay case assembly 300 identical to delay case assembly 300 of fuzes 100a and 100b is inserted in bore 260. 
     Head 202c has a pair of opposed side walls 220c of substantially rectangular profile, a front wall 222c, a back wall 224c opposite front wall 222c and inset from the back edges of side walls 220b, a top wall 226c inset from the top edges of front wall 222c and side walls 220c, and a bottom wall 228c opposite top wall 226c. Side walls 220c include a pair of opposed, parallel extensions 230c extending downwardly from bottom wall 228c. Side walls 220c also include an upper pair of opposed circular apertures 240c adjacent their back, upper corners, and a lower pair of opposed elongated slots 244c spaced downwardly from upper circular apertures 240c and extending into the extensions 230c, all for a purpose to be described hereinafter. Front wall 222c includes a pair of hinge lugs 250c extending from the top thereof, identical to hinge lugs 250a of fuze 100a. 
     Squaring of head 202c of fuze body 200c gives fuze body 200c a longer fulcrum arm than fuze body 200b with its angled head 202a. 
     An initiator lever assembly 500c is mounted to fuze body 200c and rotatable between an unprimed position and a primed position. Initiator lever assembly 500c comprises an initiator lever 502c elongated to define a handle to be restrained while holding and throwing the grenade G and having a longitudinal plane of symmetry, a distal end 504c, and a proximal end 506c.  Initiator lever 502c is substantially planar adjacent proximal end 506c and curved adjacent distal end 504c. 
     A pair of opposed ears 510 extend from proximal end 506 of initiator lever 502 parallel to the plane of symmetry. Ears 510 include a pair of opposed circular apertures 512. Proximal end 506c of initiator lever 502c is positioned between side walls 220c of fuze body 200c with apertures 512 in ears 510 in registration with upper apertures 240c in side walls 220c. A pin 520 is inserted through apertures 512 and apertures 240c, allowing initiator lever 502c to rotate between a first position corresponding to the unprimed position of initiator lever assembly 500c and a second position corresponding to primed position of initiator lever assembly 500c. 
     A firing pin 530 is formed integrally with initiator lever 502c, firing pin 530 being positioned on initiator lever 502c to engage primer 320 when initiator lever 502c is in its second position and initiator lever assembly 502c is in its primed position. A coil spring 540 is mounted around pin 520, one end 542 of spring 540 extending outwardly and engaging initiator lever 502c and the other end 544 bearing against back wall 224c of fuze body head 204c to bias initiator lever 502c in its second position. 
     Primer 320 is protected by a cover assembly 600c, which also bears against and in part covers initiator lever assembly 500c in its unprimed position. Cover assembly 600c comprises a cover piece 602c having the same longitudinal plane of symmetry as initiator lever 502c and having a top portion 604c covering the top of fuze body head 202c, a bottom portion 606c covering the back edges of side walls 220c, a lower surface 608c facing fuze body head 202c, and an upper surface 610c opposite lower surface 608c. Top portion 604c includes at its front edge a hinge clasp 620c for engaging hinge lugs 250c over its top, so that cover assembly 600c can rotate upwardly around hinge lugs 250c when initiator lever assembly 500c is released from its unprimed position. Clasps 620c wrap around the top of hinge lugs 250c to provide a faster release for cover assembly 600c than is possible where the hooks wrap around the bottom, as in fuze 100b. 
     Bottom portion 606c includes a pair of side extensions 630c (FIG. 8) extending substantially perpendicular to lower and upper surfaces 608c and 610c. Side extensions 630c include a pair of opposed circular apertures 632c in registration with the upper ends of elongated slots 244c in side walls 220c. 
     A rotatable safety latch 640 identical to safety latch 640 of fuze 100a is mounted on bottom portion 606c of cover piece 602c for retaining initiator lever 502c in its unprimed position. Lugs 642 are mounted below lower surface 608c of bottom portion 606c of cover piece 602c for engaging slots 244c, and a dial 644 is mounted above upper surface 610c of bottom portion 606c. Dimples 660c in cover piece 602c are engaged by ball 650 of safety latch 640 (FIG. 9). 
     Initiator lever 502c is further retained in its unprimed position by a pull ring assembly 700 identical to pull ring assembly 700 of fuze 100a. Cotter pin 702 of pull ring assembly 700 is inserted through the upper ends of lower elongated slots 244c in side walls 220c and circular apertures 632c in cover assembly 600c. 
     In operation, to prepare grenade G to be thrown, pull ring assembly 700 is removed from safety fuze 100c by pulling on pull ring 704. Once cotter pin 702 has been removed from apertures 632c and slots 244c, safety latch 640 is rotated to disengage lugs 642 from slots 244c and cover assembly 600c is removed. Spring 540 is then free to urge initiator lever 502c into its primed position. 
     From the above, it is apparent that many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.