Hand grenade

An improved hand grenade incorporating safety features including a normally uncocked striker arm and a protective shield over the primer. Because the striker spring is normally unstressed, the major working parts of the grenade may be inexpensively made from plastics.

BACKGROUND OF THE INVENTION 
The hand grenade has been used as a weapon in warfare since the fifteenth 
century. During the seventeenth and eighteenth centuries specially trained 
men known as grenadiers were armed with hand grenades. In World Wars I and 
II all armies had them and they have been employed effectively in the more 
recent conflicts including the Korean and Vietnamese wars and in guerrilla 
activities all over the world. 
A grenade is a small explosive bomb with the first grenades looking like 
pomegranates. Presently, there are fragmentation granades with cast iron 
or steel containers that shatter into many pieces when they explode and 
chemical grenades comprising steel containers filled with phosphorous, 
tear gas or smoke producing materials. These grenades may be thrown by 
hand, fired from a hand-held weapon or hurled from a grenade launcher. 
The modern hand grenade typically comprises a cast iron or steel body which 
holds the explosive charge, a detonator which ignites the charge, a time 
delay train leading to the detonator, a primer, a striker, a striker 
spring, a safety lever and a safety pin. The striker is always in the 
cocked position from the time of manufacture with the striker spring under 
pressure. A catch at one end of the safety lever restrains the striker so 
long as the lever is held against the body of the grenade, and the safety 
pin secures the position of the safety lever until the pin is pulled. 
When using the grenade it is grasped in the throwing hand with the safety 
lever held against the body of the grenade. The safety pin is then 
removed. As the grenade leaves the hand during the course of its being 
thrown toward a target, the safety lever springs outward releasing the 
striker. The striker impacts the primer igniting the time delay train. The 
time delay train begins burning at one end and the burning progresses 
toward the opposite end at a relatively low rate of travel. After a 
predetermined period of time, the burning reaches the detonator, the 
detonator fires and ignites the explosive charge causing the body of the 
grenade to explode, scattering fragmented shrapnel over the target area. 
If the device is a chemical grenade it gives off smoke or tear gas when 
ignited. 
Grenades of this type have been made almost entirely of metal, including 
the body, the safety lever and the striker mechanism. Fabrication from 
metal has been necessary in order to assure safety for the user. Because 
the striker is always in the cocked position, materials have had to be 
employed that are not subject to creepage which might result in a 
premature release of the striker mechanism. Fabrication from plastics has 
thus been precluded and the cost of the grenade has accordingly remained 
relatively high. 
Even when fabricated from metal, the present grenade design with its 
normally-cocked striker is inherently unsafe. From the aspect of safety an 
improvement could be achieved in a design configuration employing a 
striker mechanism that is not cocked until use is imminent. 
An improved grenade design is thus much to be desired. In particular, such 
a design should be made inherently safe for the user even when fabricated 
from inexpensive plastic materials. 
SUMMARY OF THE INVENTION 
In accordance with the invention claimed, an improved hand grenade is 
provided in a form which is inherently less hazardous to the user even 
when fabricated inexpensively from plastic materials. 
It is, therefore, one object of this invention to provide an improved hand 
grenade. 
Another object of this invention is to provide an improved hand grenade 
which is inherently safe for the user. 
A further object of this invention is to provide an improved hand grenade 
in which added assurance of safety is provided through the use of a 
striker mechanism that is not cocked until immediately prior to the use of 
the grenade. 
A still further object of this invention is to provide an improved hand 
grenade which may be fabricated inexpensively from plastic materials 
without compromising the safety of the device. 
Yet another object of this invention is to provide an improved hand grenade 
which affords in addition to the foregoing benefits a means for selecting 
either of two operating modes; including a choice of smoke or tear gas 
emission or a bursting mode. 
Further objects and advantages of the invention will become apparent as the 
following description proceeds, and the features of novelty which 
characterize the invention will be pointed out with particularity in the 
claims annexed to and forming a part of this specification.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring more particularly to the drawings by characters of reference, 
FIGS. 1-6B disclose an improved hand grenade 10 comprising a body 11, a 
striker arm 12, a striker spring 13, a sear 14, a safety lever 15, a 
primer 16, a time delay train 17, a chamber 18 for holding the explosive 
charge, and a safety pin 19. 
The body 11 is generally cylindrical and it has two parallel plates 21 and 
22 extending upward from its upper end. Reinforcing ribs 23 and 24 secure 
the upright position of plates 21 and 22, respectively. The lower 
cylindrical portion of the body 11 houses the time delay train 17 and the 
chamber 18; plates 21 and 22 serve as a mounting frame for striker arm 12 
and safety lever 15. 
Striker arm 12 has two curved side members 25 and 26 joined at their ends 
by transverse webs 27 and 28 in a form resembling a picture frame. The 
forward web 27 supports near its center a firing pin 29 as shown most 
clearly in FIG. 4B. The rearward web 28 serves as a finger grip for 
cocking the striker mechanism. The lengths of the webs 27 and 28 are 
somewhat shorter than the separation distance between plates 21 and 22 so 
that striker arm 12 passes freely between plates 21 and 22. A pivot pin 31 
passes through corresponding points near the centers of side members 25 
and 26 and through aligned holes in plates 21 and 22 to pivotally mount 
arm 12 between plates 21 and 22. This pin may be made of plastic and 
molded integrally with the striker arm. Striker spring 13 is mounted over 
the center portion of pin 31 with one end 32 bearing against the underside 
of web 28 and its other end 33 bearing against the top surface of a 
tapered upper edge 34 of body 11. Ends 32 and 33 are in compression 
against the torsional force of spring 13 and they urge the web 28 upward, 
applying a counterclockwise moment of force against arm 12 about pin 31. 
If arm 12 is unrestrained by other mechanisms, it is forced to rotate in a 
counterclockwise direction as viewed in FIG. 4C until firing pin 29 
strikes the center of the primer 16 which is located near the edge of the 
top surface of body 11 at a position directly opposite edge 34. 
Safety lever 15 has the general form of an inverted "L". The outer tip of 
the shorter leg that is ordinarily the base of the "L" is pivotally 
mounted between plates 21 and 22 by means of a pivot pin 35. Pin 35 passes 
perpendicularly through plates 21 and 22 at a position directly above edge 
34 with clearance provided between pin 35 and edge 34 for the rotational 
movement of striker arm 12. 
As may be noted from a comparison of FIGS. 1, 4A 4B and 4C, lever 15 moves 
rotationally about pin 35 from a downward position, in which the longer 
leg of the "L" rests against a depression in the side of body 11, to the 
extended or lifted position shown in FIG. 4C. 
The sear 14 is "T"-shaped, comprising a vertical leg or sear bar 36, and a 
cross-piece 37. As shown in FIG. 5, bar 36 and cross-piece 37 form an 
integral one-piece member with cross-piece 37 arranged perpendicularly 
across the top surface of bar 36 at one end of bar 36. A spreading 
wedgeshaped projection from the opposite face of bar 36 at the same end is 
slidably captured between two parallel undercut rails 38 and 39 which 
project downward from the underside of the shorter leg of the "L"-shaped 
lever 15. The sliding motion of the sear 14 within rails 38 and 39 is in a 
direction parallel with the plates 21 and 22 of body 11. 
On the side of lever 15 facing the body 11 at a point just above the top 
surface of the cylindrical portion of body 11 a flat horizontal tab 41 
extends inward, barely clearing the primer 16 vertically and completely 
covering primer 16 when lever 15 is lowered against body 11. A depression 
42 in the center of the top surface of tab 41 directly above the primer 16 
receives the tip of the firing pin 29 when the striker arm 12 is set in 
the safety position as shown in FIGS. 1 and 4A. 
Extending upward from the base of tab 41 in a direction parallel with the 
larger vertical leg of lever 15 is a sear spring 43. Sear spring 43 is 
integral with lever 15. Spring 43 is a flat cantilevered strip with its 
tip 44 bent perpendicularly toward the end of the sear 14. As shown in 
FIG. 4A the spring 43 drives the sear 14 to the right and away from the 
longer leg of lever 15. 
Referring again to FIG. 5, it will be noted that the ends 45 and 46 of 
cross-piece 37 extend beyond the edges of lever 15. As shown in FIG. 1, 
the ends 45 and 46 also extend past the edges of plates 21 and 22, and, in 
the lowered position of lever 15 they are captured in notches 47 and 48 
which are formed in the edges of plates 21 and 22. In this position of the 
lever 15 the spring 43 drives the sear 14 to the right, urging the ends 45 
and 46 into the notches 47 and 48. The capture of ends 45 and 46 by the 
notches 47 and 48 in this manner secures the downward position of the 
lever 15 as shown in FIGS. 1 and 4A. This is the uncocked condition of the 
grenade 10 in which the force of the spring 13 is substantially relaxed, 
the primer is guarded by the tab 41, and the position of the safety lever 
15 is secured by the captured cross-piece 37 with help from the capture of 
the lower end of the firing pin 29 in the depression 42 of tab 41. 
To cock the striker arm 12 the longer leg of lever 15 is held against body 
11 while applying a downward force to the serrated top surface 49 of web 
28. Arm 12 is caused thusly to rotate in a clockwise direction. 
Concurrently, the web 27 at the opposite end of arm 12 is caused to move 
arcuately upward and to the right. As web 27 moves past bar 36 of sear 14, 
its outer edge impinges against the under surface of bar 36 deflecting bar 
36 upward, then moving past its edge just prior to reaching the clockwise 
rotational limit of arm 12. As pressure is subsequently released from 
surface 49, spring 13 urges arm 12 in a counterclockwise direction until 
the top of web 27 impinges against the end of bar 36 driving bar 36 and 
sear 14 leftward against the lesser force of spring 43 and releasing ends 
45 and 46 from the notches 47 and 48. FIG. 1 shows the association of 
releasing end 45 and notch 47 with releasing end 46 and notch 48 being 
similarly arranged. This is the cocked condition of the grenade 10, and to 
prevent the striker arm 12 from being fully released, it is necessary to 
hold the lever 15 against the body 11 until the instant the grenade leaves 
the user's hand in the process of being thrown. 
It will be noted that in the unlikely event that the bar 37 should break 
and thereby release arm 12 under the force of the spring 13, the firing 
pin will simply impact the tab 42 which remains in position over the 
primer 16 so long as lever 15 is held against body 11. The primer 16 is 
thus prevented from firing. 
In the normal manner of dispatching the grenade, the tab or safety pin 19 
is pulled and then the grenade is set to the cocked position just 
described and as illustrated in FIG. 4B. As the grenade then leaves the 
hand in the process of being thrown, the force 51 against lever 15 is 
released. Simultaneously, the force of spring 13 driving web 27 against 
the end of bar 36 causes lever 15 to swing outward in the direction 52 as 
shown in FIG. 4C. Bar 36 at the same time moves away from its position of 
restraint against the clockwise rotation of arm 12, and arm 12 is released 
with the result that it rotates very rapidly to its counterclockwise 
position causing pin 29 to impact and fire the primer 16. As the primer 16 
is fired it ignites the time delay train 17 which burns at a controlled 
rate to initiate the detonation of the explosive charge in chamber 11 at a 
predetermined time later. As shown in FIGS. 4A, 4B and 4C, the time delay 
train 17 is generally cylindrical and it extends vertically downward from 
a point directly under primer 16 into the center of the chamber 18. 
As an added measure of safety, the safety pin 19 may be employed to prevent 
the cocking of the grenade. As shown in FIGS. 1 and 4A the body of the pin 
19 is passed through two holes 53 and 54 in plates 21 and 22, 
respectively. The holes 53 and 54 are positioned in plates 21 and 22 such 
that when arm 12 is in the uncocked position of FIGS. 1 and 4A the body of 
pin 19 passes under arm 12, in which position it prevents arm 12 from 
being rotated in the clockwise direction for cocking. 
Because the striker arm is left in the uncocked position until just prior 
to the use of the grenade 10, and because the spring 13 is thus normally 
in a relaxed condition, the major parts of the grenade (with the exception 
of the spring 13, the firing pin 29, the primer 16 and the pivot pins 31 
and 35) may be inexpensively made of plastic by injection molding. This is 
in contrast with the conventional grenade in which the normally cocked 
striker mechanisms would be subject to creepage and failure if they were 
made of plastic. 
The intentionally smooth and flush contours of the grenade 10 as shown 
particularly in FIG. 1 permit the grenade to be fired from a grenade 
launcher. As noted from FIG. 1, the safety lever 15 when held in the 
safety position rests in a groove 55 which extends longitudinally down the 
side of the body 11. 
FIGS. 6A and 6B disclose a modification which affords in addition to the 
benefits described above for the structure shown in FIGS. 1-5 a dial or 
selector means 57 for selecting either one of two operating modes, i.e. a 
burning mode for smoke or tear gas grenades or a bursting mode. In this 
modification the hand grenade 58 comprises all of the structure described 
in the description of FIGS. 1-5 but differs therefrom by having an 
additional chamber 18'. Chamber 18 contains the explosive charge while 
chamber 18' contains a burning charge. 
Thus, the user may preselect the operating mode of the grenade at any time 
prior to throwing it by selectively rotating the dial 57 from a "safe" 
position to either the "burn" or "burst" positions shown. The dial or 
selector means comprises a circular configuration having a pair of 
passageways 59 and 60 extending radially outwardly of an interconnecting 
passageway 61 which is axially aligned with the primer train as shown in 
FIG. 6B. It should be noted that a sliding fit of close limits should be 
provided between the top surface 62 of dial 57 and the end of the 
passageway 63 of time delay train 17 so that the burning powder of the 
time delay train 17 cannot bypass the passageways by flashing out between 
the top surface 62 of dial 57 and ignite the materials in the non-selected 
chambers 18, 18' or both. 
Although but a few embodiments of the invention have been shown and 
described, it will be apparent to those skilled in the art that various 
changes and modifications may be made therein without departing from the 
spirit of the invention or from the scope of the appended claims.