US3601060A

US3601060A - Antidisturbance device

Info

Publication number: US3601060A
Application number: US820105A
Authority: US
Inventors: Torbjorn Thuen
Original assignee: P A O D Inc
Current assignee: P A O D Inc
Priority date: 1969-04-29
Filing date: 1969-04-29
Publication date: 1971-08-24
Anticipated expiration: 1988-08-24

Abstract

A disturbance-sensitive device adapted to be actuated when the device is subjected to a shock above a predetermined threshold limit or when the angle which the device makes with the ground is varied. The device is provided with a timer adapted to initially arm the device for disturbance actuation after a first predetermined period and to thereafter trigger the device after a second predetermined period in the event that no intervening disturbance occurs between the first and second periods.

Description

United States Patent lnventor Torbjorn Thuen Roscland, NJ. Appl. No. 820,105 Filed Apr. 29, 1969 Patented Aug. 24, 1971 Assignee P.A.0.D. Inc. F airfield, NJ.

ANTIDISI'URBANCE DEVICE 12 Claims, 9 Drawing Figs.

US. Cl 102/76 P, 102/78 Int. Cl F42c 7/00, F42c 7/02, F42c 15/24 Field of Search 102/78, 76, 81, 70.2

[56] References Cited UNIT ED STATES PATENTS 1,322,521 11/1919 Biffi 102/76 3,015,276 1/1962 Surtees.. 102/76 3,431,376 3/1969 Kenzie... 102/702 X 3,492,444 1/1970 Offie 102/702 X Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Thomas H. Webb Attorneyl(ane, Dalsimer, Kane, Sullivan and Kurucz ABSTRACT: A disturbance-sensitive device adapted to be actuated when the device is subjected to a shock above a predetermined threshold limit or when the angle which the device makes with the ground is varied. The device is provided with a timer adapted to initially arm the device for disturbance actuation after a first predetermined period and to thereafter trigger the device after a second predetermined period in the event that no intervening disturbance occurs between the first and second periods.

Patented Aug. 24, 1971 3,601,060

4 Sheets-Sheet 1 3 152 3 l i l INVENTOR 24 I 4 70/?81/0? 77/!!! ATTORNEYS Patented Au 24, 1971 3,601,060

4 Shoots-Shut 5 INVENTOR 70/?3/0! 7 1905 I) ANTIDISTURBANCE DEVICE BACKGROUND OF THE INVENTION Antidisturbance devices are extensively used in military applications as fuses on ordinance devices such as mines. Such fuses serve to detonate the mines explosive charge when an enemy object approaches, strikes, or in other ways disturbs the equilibrium of the fuse. In order to initiate the typical prior art antidisturbance device, the enemy object had to impart a mechanical shock or acceleration to the unit in excess of a threshold limit. This is undesirable since if such a prior art mine were detected and handled carefully, it could be removed, disarmed, or in other manners disposed of by the enemy without exceeding the required threshold. Thus, the need has arisen for an extremely sensitive antidisturbance device, the actuation of which may be initiated by either the imparting of a shock thereto or by merely changing the angle the mine makes with the ground.

Another shortcoming of the typical prior art mine is that once the mine is placed, it may remain in position in an armed state after enemy objects have left the vicinity and thus pose a threat to friendly and civilian objects. This danger exists especially in those instances where the mines are indiscriminately dropped over an enemy-held area so that no map of the mine field could be accurately charted.

It is, therefore, a principal object of the present invention to provide a new antidisturbance device which, once armed, may be actuated either by the imparting thereto of an acceleration above a threshold limit, or by merely changing the angle which the device makes with the ground and which, after remaining in an armed condition for a predetermined period of time, will self-trigger.

SUMMARY OF THE INVENTION These and other beneficial objects and advantages are attained in accordance with the present invention by providing a disturbance-sensitive mechanism including a housing having a top surface through which a channel extends. A ball is positioned within the channel for movement therein. A lever pivotally mounted to the housing surface is provided with spaced apart arms overlying the channel on opposite sides of the ball. The mechanism is further provided with a firing mechanism which is held'against movement by interengagement with portions of the lever when the lever is in a first, predetermined position. Means to positively retain the lever in the first position are also provided as in a timing device which, upon being set, is adapted to remove the aforementioned means after the lapse of a predetermined time interval whereafter movement of the lever removes the portions of the lever restraining said firing mechanism from engaging and restraining the trigger arm. Such lever movement may be attained either by imparting a shock to the lever sufficient to overcome the friction of the lever pivot joint and the engagement pins, or by merely tilting the device whereby to cause the ball to roll and strike one of the lever arms which in turn will cause the lever arm to rotate about the pivot joint. The timing device is further adapted, after the lapse of a second predetermined period of time, to impart motion to said lever in the event that no intervening outside force causes the disassociation of said firing mechanism restraining portion and said firing mechanism whereby to remove the portions of the lever which hold the firing mechanism against movement.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. I is a fragmentary side elevational view partially in section of a disturbance-sensitive mechanism in accordance with the present invention, the mechanism is shown in an unarmed state;

FIG. 2 is a top plan sectional view taken along reference lines 2--2 of FIG. 1 in the direction indicated by the arrows;

FIG. 3 is a sectional view taken along reference lines 3-3 of FIG. 2 taken in the direction indicated by the arrows;

FIG. 4 is a sectional view taken along reference lines 4-4 of FIG. 2 in the direction indicated by the arrows;

FIG. 5 is a fragmentary side elevational view partially in section similar to FIG. 1 depicting, the antidisturbance mechanism of the present invention in the armed condition at the instant just prior to detonation;

FIG. 6 is a top plan sectional view similar to FIG. 2 taken along reference lines 6-6 of FIG. 5 in the direction indicated by the arrows;

FIG. 7 is a sectional view similar to FIG. 3 taken along reference lines 7 7 of FIG. 5 in the direction indicated by the arrows showing the mechanism of the present invention just prior to detonation at the conclusion of the second predetermined time interval;

FIG. 8 is a sectional view taken along reference lines 88 of FIG. 6 in the direction indicated by the arrows; and

FIG. 9 is a perspective view of a camming member forming a component of the present device.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is illustrated in the accompanying drawings wherein identical components are referred to by the same numeral throughout the several views. In this preferred embodiment, as seen in FIG. 1, the antidisturbance mechanism 10 is positioned at the top end of a casing 12 which in turn is coupled to a mine. The device 10 is contained within housing 16 which includes a top surface 18 spaced somewhat below the top surface 20 of casing 12. A channel 22 extends across top surface 18 from end to end and divides the housing into two portions, a rear portion 34 and a front portion 36. The depth of channel 22 is slightly less than the spacing between the underside of the casing top 20 and the housing top surface 18 and a steel ball 24 rides in the channel constrained from falling out cooperatively by the

sidewalls

26 and 28 of the channel and the underside of the casing top surface 20. In this preferred embodiment, the housing is formed of a plastic material while the various moving parts are formed of a suitable metal as is the mine and casing.

Referring now to FIG. 2, it is noted that a generally kidneyshaped lever 30 is pivotally mounted to the rear portion 34 of surface 18 free to rotate about pivot pin 32 which extends into the housing interior. Lever 30 includes two

arms

38 and 40 which overlie channel 22 on opposed sides of ball 24 and are spaced apart from one another a distance substantially greater than the diameter of ball 24. A section 42 of lever 30 connects the ends of

arms

38 and 40 overlying the housing front portion 36. A tab 44 coupled to section 42 depends downwardly into a suitable cutout 46 in the housing top surface so that the ends 48 and 50 of cutout 46 limit the arcuate path of motion that lever 30 may travel by limiting the displacement of tab 44. As seen in FIG. 1, tab 44 includes a narrow bottom portion 52 which extends upwardly for some distance and then gradually widens along diagonal line 54 to the underside of lever 30.

A lever arm 56 is also pivotally mounted to the top surface 18 of the housing. Lever 56 has coupled thereto a downwardly depending shaft portion 58 which extends into bore into the housing interior and forms the pivotal coupling between arm 56 and the housing. The depth of bore 70 is somewhat less than the length of shaft 58 so that lever 56 overlies lever 30. A pin 60 extends upwardly from the top surface of lever 30 and a similar pin 62 extends downwardly from the free end 64 of lever arm 56.

Pins

60 and 62 are positioned on their respective levers so as to have a common intersection point on their levers paths of motion and their lengths or such as to enable them to engage one another without otherwise interfering with the motion of their levers, as shown in FIG. 4.

Passageways

66 and 68 in the form of cylindrical bores extend through the housing interior substantially transverse to channel 22 below the bottom of the channel. Bore 66 underlies cutout 46 and bore 68 partially intersects bore -70 so that a portion of shaft 58 may extend into passageway 68. Passageway 66 contains the timing mechanism 72 and passageway 68 contains the firing mechanism 74 of the present antidisturbance device.

The timing mechanism 72 is of the type disclosed in the application for Letters Patent Ser. No. 770,205 filed Oct. 24, 1968 entitled LIQUID ANNULAR ORIFICE DASI-IPOT TIMER, now abandoned, and the continuation-in-part application thereof bearing the same title and currently pending, which was filed on Dec. 9, 1968 and assigned Ser. No. 816,132. In essence, the timer 72 comprises a cylinder 76 closed at one end 78 by the cylinder bottom 80 and open at the other end 81. A spring 82 is positioned within the cylinder and is designed to normally urge the spherical piston 84 toward the open end of the cylinder as shown. A liquid 86 having prescribed properties in accordance with the aforementioned patent applications fills the remaining portion of the cylinder and a rubber boot 88 overlies the open cylinder end 81 and seals the same. A plunger 90 is mounted externally of cylinder 76 within a conduit 92 that is aligned with the center of the cylinder open end 81. In this connection, cylinder 76 is contained within an outer cylinder 94 having an end plate 96 with an orifice therein communicating with conduit 92. Thus, plunger 90 is designed to move axially through conduit 92 and in this regard, the forward end 98 of the plunger is sharpened to a point so as to enable it to penetrate the rubber boot 88 to engage the piston 84. The interior wall 100 of cylinder 76 comprises two portions of differing diameter. Thus, the interior wall 100 has a forward portion 102 of relatively large diameter and a rear portion 104 of a relatively reduced diameter. By reason of this structure, the piston 84 will move through the forward portion of the cylinder more rapidly than through the rear portion. In the present invention, as applied to a mine, for example, this feature is utilized to trigger the arming mechanism after a first predetermined time which may be a few minutes, and then to trigger a self-destruction mechanism after a second predetermined time interval which may be hours, days, or even months later.

The bottom end 106 of plunger 90 is seated in an axial bore 108 extending from the forward end 110 of an elongated generally cylindrical member 112 which is also positioned in passageway 66 spaced apart from the dashpot timer. The other end 114 of member 112 seats against a shim 116 which in turn abuts the casing 12 of the mechanism. An elongated annular channel 118 extends from end 114 of member 112 for the major part of the length of the member and a spring 118 in compressed form is positioned within the channel extending between the shim 116 and the bottom of the channel. Spring 119 thus exerts a force on member 112, tending to drive member 112 and hence plunger 90 toward the timing mechanism 72. An arming pin 122 provided with a radially outwardly extending flange portion 124 interposed between its top and bottom ends is provided in a bore 126 that extends downwardly from the top surface 20 of the casing through the housing adjacent member 112. The sidewall 128 of member 112 adjacent bore 126 includes inwardly extending portions 130 adapted to engage flange 124 of pin 122. This interengagement prevents the movement of member 112 under the action of spring 118. It should be noted, however, that the inwardly extending portion 130 of member 112 continues to the top of member 112 and hence the flange 124 and member 112 may be disengaged by shifting pin 122 upwardly. An arming pin spring 132 is positioned between shoulder 134 of bore 126 and the underside of flange 124 and normally tends to drive the pin 122 upwardly so as to disengage the flange 124 and member 112 thereby enabling spring 118 to drive member 112 toward timer 72. Openings 136 extend through the shank of pin 122 and a safety wire 138 is provided that normally extends through a suitable opening in the sidewall of casing 12 to engage one of the openings I36 thereby preventing vertical movement of the pin. It should be apparent that when safety wire 138 is removed by pulling it outwardly from the casing, spring 132 will drive pin 122 upwardly, unless it is constrained by the manner in which several mines are packaged, causing flange 124 to disengage from member 112 whereafter spring 119 will drive member 118 and hence plunger toward timer 72. An annular ring 140 is disposed about the forward portion of pin 122 fixed to the housing and serves to maintain the alignment of pin 122 as it is driven upwardly under the effect of spring 132.

Referring again to FIGS. 1, 2, and 9, and to member 112 in particular, it is noted that the top surface 142 of member 112 includes a first channel 144 which extends inwardly from end 110 of member 112 and the width of which is substantially equal to that of the narrow bottom portion of tab 52. It is further noted that the narrow portion 52 of tab 44 initially rides in channel 144, thus preventing lever 30 from rotating about pin 32. The bottom end 146 of channel 144 communicates with a transverse channel 148 extending across the entire top of member 112 so as to permit free rotation of lever 30 when the tab is positioned in this channel. Thus, as member 112 is driven upwardly under the action of spring 118, the lever will first be prevented from rotation until such time as the narrow portion 52 of tab 44 clears longitudinal channel 144 and enters transverse channel 148. The length of channel 144 is substantially equal to the length of the forward portion 102 of the timer cylinder and hence the time required for the piston 84 to move through the forward portion of cylinder 76 determines the time during which the lever is restrained from moving by the sidewalls of channel 144. Spaced downwardly from the bottom end 146 of channel 144 and forming a wall of transverse channel 148 is the camming surface 150. Camming surface 150 is designed to engage the lower portion 52 of tab 44 as member 112 is urged toward cylinder 76 and to thereby cause the rotation of lever 30 about pin 32 by virtue of tab 44 riding along the camming surface.

The firing assembly 74 of the antidisturbance device of the present invention is contained in passageway 68. In this regard, the firing mechanism 74 includes a firing pin 152 fixed t0 the front end of passageway 68 and a spring-loaded slider assembly 154 shiftably mounted within passageway 68 and free to move therein toward the firing pin. The sliding assembly 154 includes a slider 156 which is substantially a cylindrical member having a diameter substantially equal to that of the inner diameter of the bore. A channel 158 extends from the forward end 160 of slider 156 rearwardly to shoulder 162. Channel 158 is positioned along the surface of slider 156 that abuts the surface of the housing defining the side of passageway 68 through which bore 70 extends. In this regard, it should be noted that bore 70 partially extends into bore 68. The length of channel 158 is such that when slider 156 is disposed in the most rearward portion of bore 68, shoulder 162 aligns substantially with the center of bore 70. A groove in the side of slider 156 prevents it from rotating within the passageway.

The depending shaft portion 58 of lever 56 which extends into bore 70 is generally round in configuration although the shaft has a substantially semicircular cross-sectional configuration over a portion 159 coextensive with the height of slider 156. The chord 164 of the center portion 159 of shaft 58 is adapted to extend into channel 158 to engage shoulder 162 and hence prevent movement of slider 156 toward the firing pin 152 when lever 56 is properly oriented. However, rotation of lever arm 56 will cause a corresponding rotation of chord 164 so as to cause the chord to align with the surface 166 of bore 68 in the manner shown in FIG. 7.

A firing spring 168 is positioned between the base of bore 68 and a spring-receiving recess 170 extending forwardly from the rear surface 172 of slider 156, Spring 168 tends to urge slider 156 toward the firing pin, however, this motion is prevented by the interengagement of chord 164 and shoulder 162 when the lever arm 56 is in the position shown in FIG. 2. As was previously mentioned, the frictional engagement between

pins

60 and 62 of

levers

30 and 56, respectively, maintain lever arm 56 in this position. A detonator 174 is positioned in a recess 176 extending from the forward end 160 of slider 156 in axial alignment with firing pin 152. An additional detonating charge 178 is contained within lead cup 180 which extends downwardly from bore 68 below pressure pad 186 into the body of the mine wherein a mixture of explosive charge 182 and pellets are contained within a fragmentation cup 184 which is coupled to casing 12.

The operation of the antidisturbance device of the present invention may thus be understood in conjunction with a comparison of the elements of FIGS. 1 through 4 which show the device in an unarmed state and FIGS. 5 through 8 which show the device in an armed state immediately prior to detonation. Thus, the mine is activated by removing the safety wire 138 by pulling it outwardly in the direction of the arrow in FIG. 4. This permits the arming pin 122 to move upwardly under the action of spring 132 to the position shown in FIG. 5. Flange 124 will thereby disengage the inwardly extending portions 130 of member 112 enabling spring 119 to drive member 112 forward toward cylinder 76. By so doing, the tip 98 of plunger 90 will penetrate boot 88 and contact piston 84 and will drive the same upwardly against the action of spring 82. After a first predetermined period of time has elapsed, (this period being determined by the characteristics of the timer 72 and generally being on the order of a few minutes) member 112 will have moved sufficiently to release the lower portion 52 of tab 44 from channel 144. At this point, the antidisturbance device is in a loaded condition and any further disturbance will set off the device. Also, at this point, the piston 84 begins entering the restricted portion of the timer cylinder and the self-destruct time begins. If the mine is disturbed or its angle is changed, the disturbance ball 24 will travel in channel 22 in one direction or the other, bumping into either

arm

38 or 40 of lever 30, thereby causing it to rotate about pivot pin 32. The rotation of lever 30 causes the mating pins 60 and 62 of

levers

30 and 56, respectively, to disengage, which then permits the lever arm 56 and the dependent portion thereof 58 to rotate counterclockwise under the torque imposed on the chord 164 of the center 159 of shaft 58 by shoulder 162 of slider 156. When the lever arm 56 has rotated approximately 90, the slider assembly 156 is released, allowing the detonator 174 to impinge on firing pin 152, thus, exploding the mine. The necessary position of lever 56 for detonation to take place is shown in FIG. 6 wherein it is assumed that the ball 24 has rolled to strike arm 40 of lever 30. The position of the detonator at the instant of detonation is depicted in FIG. 7 and 8.

In the event the mine remains undisturbed for a second predetermined length of time, the anti-disturbance device of the present invention is provided with a self-destruct feature which serves to then detonate the mine.- In this regard, it is to be remembered that member 112 is constantly moving toward cylinder 76 at a predetermined rate and that in time, the bottom 52 of tab 44 will engage the camming surface 150 of member 112. As this camming surface continues to move toward the cylinder 76, tab 44 will ride down the camming surface, thereby causing lever 30 to rotate clockwise about pin 32 and in due course, this rotation will cause the disengagement of

pins

60 and 62 whereby to permit lever arm 56 to be rotated under the torque imposed on shaft 58 by the slider assembly 156 as before. Thus, when the piston 84 attains the position shown in FIG. 7, the mine will self-destruct even though ball 24 has not been disturbed.

Thus, in accordance with the above disclosure, the aforementioned objects are attained.

What is claimed is:

'1. A disturbance sensitive mechanism comprising: a housing; a channel extending across the top surface of said housing; a ball positioned within said channel for movement therein; a lever pivotally mounted to said housing surface and having arm portions overlying said channel on opposite sides of said ball; a spring-biased firing mechanism disposed within said housing; means associated with said lever to hold said firing mechanism against actuation when said lever is in a first position; means to positively retain said lever in said first position and to prevent said lever from being moved from said first position for a first predetermined time interval whereafter said lever may be moved from said first position by the application of a force to said lever whereby to release and actuate said firing mechanism; and timing means to determine the passage of said first predetermined time interval from a desired starting point.

2. The invention in accordance with claim 1 further comprising means for initiating the start of said first predetermined period of time whereby prior to the utilization of said aforementioned means said lever is positively retained in said first position.

3. The invention in accordance with claim 2 further comprising a passageway disposed within said housing and said timing means includes: a liquid annular orifice dashpot timer positioned within said passageway, said timer including a cylinder, a liquid contained within said cylinder, and a piston disposed within said cylinder at one end and adapted to move through the liquid within said cylinder toward the opposite end at a predetermined rate; spring biased piston driving means disposed within said passageway and initially held against movement toward said piston and said initiating means includes an arming pin extending through said housing and adapted to be shifted from a first position whereby said arming pin engages said driving means and holds the same against movement to a second position wherein said arming pin and driving means disengage whereby said piston driving means is free to exert a force on said piston and to drive the same through said cylinder.

4. The invention in accordance with claim 3 wherein said piston-driving means includes a compressed spring having one end constrained against motion and the other end in operative contact with a piston-contacting member adapted to engage and move with said liquid annular orifice dashpot piston, surfaces on said member defining a lever-restraining section, and portions of said'lever adapted to engage said lever-restrainingv section whereby after said liquid annular orifice dashpot piston has moved a predetermined distance within said cylinder, thereby determining said first time interval, said lever portions and the lever-restraining portion of said member disengage whereafter said lever may be moved from said first lever position.

5. The invention in accordance with'claim 1 further comprising a second passageway through said housing and said firing mechanism is disposed within said second passageway; a compressed spring disposed within said passageway in operative contact with said firing mechanism wherein said firing mechanism is adapted to be actuated upon the expansion of said spring; and spring-constraining means coupled to said housing in operative contact with said lever and adapted to maintain said spring in a compressed condition when said lever is in said first lever position.

6. The invention in accordance with claim 5 wherein said second passageway extends through said housing substantially parallel to said housing top surface and further comprising a third passageway extending downwardly from said top surface and extending partially into said second passageway, said constraining means includes an elongated rod rotatably disposed within said third passageway and having portions extending into said second passageway in the path of travel of said firing mechanism whereby to prevent the expansion of said spring, wherein said rod portions are adapted to be shifted out of the path of travel of said firing mechanism.

7. The invention in accordance with claim 6 further comprising an arm affixed to the top end of aid rod and overlying said housing top surface, means affixed to said arm adapted to engage said lever when said lever is in said first position and to disengage said lever when said lever is moved from said first position and said arm disengages said lever, said firing mechanism spring will shift said rod portion out of the path of travel of said firing mechanism and thereafter actuate said firing mechanism.

8. The invention in accordance with claim 1 further comprising means to actuate said firing mechanism after the passage of a second predetermined time interval following the passage of said first predeterminedtime interval and means to determine the passage of said second predetermined time interval.

9. The invention in accordance with claim 8 wherein said means for actuating the firing mechanism after the passage of a second time interval includes means to shift said lever from said first lever position after the passage of said second time interval.

10. The invention in accordance with claim 9 further comprising a passageway disposed within said housing and said timing means for said first and second time intervals includes a liquid annular orifice dashpot timer positioned within said passageway, said timer including a cylinder having a first portion extending longitudinally from one end toward the opposite end and a second portion, a liquid contained within said cylinder, and a piston disposed within said cylinder at one end and adapted to move through the liquid within each portion of said cylinder toward the opposite end at predetermined rates, spring-biased driving means disposed within said passageway and initially held against movement" toward said piston, an arming pin extending through said housing and adapted to be shifted from a first position whereby said arming pin engages said driving means and holds the same against movement to a second position wherein said arming pin and driving means disengage, whereby said piston driving means is free to exert a force on said piston and to drive the same through said cylinder portions.

11. The invention in accordance with claim 10 wherein said piston-driving means includes a compressed spring having one end constrained against motion and the other end in operative motion with a piston-contacting member adapted to engage and move with said dashpot piston, a piston-contacting member disposed within said passageway, first surfaces on said member defining a lever-restraining section, portions of said lever adapted to engage said lever-restraining section, second surfaces on said member spaced apart from said first surfaces defining a camming surface, and cam follower portions of said lever adapted to ride along said camming surface whereby after said liquid annular orifice dashpot piston has moved through said first portion of said cylinder, thereby determining said first time interval, said lever portion and the lever-restraining portion of said member disengage whereafter said lever may be moved from said lever-restraining portion and after said liquid annular orifice dashpot piston has moved through said second portion of said cylinder, thereby defining said second timed interval, said cam follower portions of said lever will have ridden along said camming surface a distance sufficient to move said lever from said first position.

12. The invention in accordance with claim 11 wherein said first cylinder portion and said second cylinder portion are of differing diameters.

Claims

1. A disturbance sensitive mechanism comprising: a housing; a channel extending across the top surface of said housing; a ball positioned within said channel for movement therein; a lever pivotally mounted to said housing surface and having arm portions overlying said channel on opposite sides of said ball; a springbiased firing mechanism disposed within said housing; means associated with said lever to hold said firing mechanism against actuation when said lever is in a first position; means to positively retain said lever in said first position and to prevent said lever from being moved from said first position for a first predetermined time interval whereafter said lever may be moved from said first position by the application of a force to said lever whereby to release and actuate said firing mechanism; and timing means to determine the passage of said first predetermined time interval from a desired starting point.

4. The invention in accordance with claim 3 wherein said piston-driving means includes a compressed spring having one end constrained against motion and the other end in operative contact with a piston-contacting member adapted to engage and move with said liquid annular orifice dashpot piston, surfaces on said member defining a lever-restraining section, and portions of said lever adapted to engage said lever-restraining section whEreby after said liquid annular orifice dashpot piston has moved a predetermined distance within said cylinder, thereby determining said first time interval, said lever portions and the lever-restraining portion of said member disengage whereafter said lever may be moved from said first lever position.

5. The invention in accordance with claim 1 further comprising a second passageway through said housing and said firing mechanism is disposed within said second passageway; a compressed spring disposed within said passageway in operative contact with said firing mechanism wherein said firing mechanism is adapted to be actuated upon the expansion of said spring; and spring-constraining means coupled to said housing in operative contact with said lever and adapted to maintain said spring in a compressed condition when said lever is in said first lever position.

8. The invention in accordance with claim 1 further comprising means to actuate said firing mechanism after the passage of a second predetermined time interval following the passage of said first predetermined time interval and means to determine the passage of said second predetermined time interval.

10. The invention in accordance with claim 9 further comprising a passageway disposed within said housing and said timing means for said first and second time intervals includes a liquid annular orifice dashpot timer positioned within said passageway, said timer including a cylinder having a first portion extending longitudinally from one end toward the opposite end and a second portion, a liquid contained within said cylinder, and a piston disposed within said cylinder at one end and adapted to move through the liquid within each portion of said cylinder toward the opposite end at predetermined rates, spring-biased driving means disposed within said passageway and initially held against movement toward said piston, an arming pin extending through said housing and adapted to be shifted from a first position whereby said arming pin engages said driving means and holds the same against movement to a second position wherein said arming pin and driving means disengage, whereby said piston driving means is free to exert a force on said piston and to drive the same through said cylinder portions.