US3252417A

US3252417A - Arming and firing mechanism

Info

Publication number: US3252417A
Application number: US360537A
Authority: US
Inventors: Jr Virgil H Johnson
Original assignee: Magnavox Co
Current assignee: Philips North America LLC
Priority date: 1964-04-17
Filing date: 1964-04-17
Publication date: 1966-05-24
Anticipated expiration: 1983-05-24

Description

May 24, 1966 v. H. JOHNSON, .JR 3,252,417

ARMING AND FIRING MECHANISM Filed April 17, 1964 2 Sheets-Sheet 1 Fig. 1.

7 INVENTOR. a i VIRGIL H. JOHNSON, JR.

8 /'T BY I 1 flaw/Masha May 24, 1966 v. H. JOHNSON, JR

ARMING AND FIRING MECHANISM 2 Sheets-Sheet 2 Filed April 1'7, 1964 INVENTOR VIRGIL H. JOHNSON ,JR.

United States Patent 3,252,417 ARMING AND FIRING MECHANISM Virgil H. Johnson, Jr., (Iharnpaign, lll., assignor to The Magnavox Company, Fort Wayne, Ind, a corporation of Indiana Filed Apr. 17, 1964, Ser. No. 360,537 5 Claims. (Cl. 102-46) This invention relates generally to arming and firing mechanisms for underwater use and more particularly to a compact and reliable mechainsm which arms automatically after submergence to a predetermined depth and disarms automatically if raised above the predetermined depth.

There are many instances in which it is desirable to employ explosive charges underwater and explode them from some remote location when desired, An example is in the use of high explosive loaded sound signals. A sound signal is deployed deep down into the Water and it is desirable to be able to fire the sound signal whenever desired from some remote location.

One way of doing this is to connect an electrical cable to an arming and firing mechanism connected to the sound signal, with the cable being extended to some remote location where the necessary firing circuitry is located and from which the signal is to be fired. It is desirable that the arming and firing mechanism does not become armed until the sound signal is at the desired depth or below, and that it become disarmed whenever the signal is raised above the desired depth. So long as the sound signal is at the proper depth, it can be fired from the remote location whenever desired by applying an electrical voltage to the connecting cable.

It is, therefore, a general object of the present invention to provide an arming and firing mechanism for under water use and which becomes armed below a predetermined depth and is again disarmed whenever raised above this depth.

A further object is to provide a mechanism occupying a minimum of space and which is readily employed with the device to be exploded and with the electrical cable.

A further object is to provide a device having the foregoing charatceristics and which is reliable in operation and quite immune to acpidental firing.

A further object is to provide a device incorporating fail-safe features.

Described briefly, a typical embodiment of the present invention incorporates a case having means thereon for receiving an external electrical connector plug and having an explosive charge in a wall thereof which can be placed adjacent the explosive device to be fired by the mechanism. Means including --a rolling diaphragm are employed to hermetically seal the interior of the housing.

A rotor having a detonator therein is rotatably mounted in the housing and a piston operable by the diaphragm has a pin thereon received in a helical groove in the rotor where-by linear motion of the piston caused by the diaphragm can rotate the rotor from a normally safe position to an armed position in response to increases of pressure exterior to the housing.

A pair of electrical conductors extend from the detonator and are secured to a pair of spring contactors. The contactors are located to normally short out the conductors outside of the detonator whenever the rotor is in the unarmed position.

A pair of stationary electrical connector pins is provided for connection to the external electrical connector. Each of these pins is disposed in a position where it will be engaged by one of the contact springs upon rotation of the rotor whereupon continued rotation of the rotor to the armed positon will unshort the detonator conductors and complete an electrical path from one of the connector pins through the detonator to the other connector pin. The device is thereby armed so that Whenever an electrical voltage from an external source is applied through the cable to the connector pins, it can fire the detonator. At this time the detonator will have become aligned with the explosive charge in the wall of the housing so as to explode it and the explosive device to which the mechanism is attached.

Suitable springs are provided to oppose the motion of the piston caused by the response of the diaphragm to pressure differential there'across and these springs are thereby effective to permit arming only when the hydrostatic pressure is that of the depth at which arming is desired. The springs also disarm the device whenever the hydrostatic pressure is less than that which it would be at the desired arming depth.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims,

FIG. 1 is a section through a typical embodiment of the present invention, the section being taken on a longitudinal plane through the longitudinal axis, with a portion of the rotor, however, not being shown in section.

FIG. 2 is a cross section taken along the line 22 in FIG. 1 and viewed in the direction of the arrows.

FIG. 2A is a cross section taken the same as FIG, 2, but with the rotor rotated to the armed position.

Referring now to the drawings in detail, a generally cylindrical case 11 is provided with

shoulders

12, 13, and 14 therein. A header assembly 16 is provided in one end of the case and includes the header body 17 hermetically sealed to the case by the O-ring seal 18, the end 19 of the case being rolled over the end 21 of the header body to hold the header assembly in place against the shoulder 12 in the case 11.

Electrical contact pins

22 and 23 are hermetically sealed to the header body by means of the

seals

24 and 26, and extend into the interior of the housing. These pins provide for electrical connection to a plug 27 insertable into the end of the header assembly and connected by a cable 28 to some external firing circuitry at a remote location. An O-ring seal 29 is provided in the groove 31 in the header body for sealing to the connector 27 when the connector is installed.

A rotor assembly 32 is provided in the housing' and includes the rotor body 33 having the outer cylindrical wall 34 received in the cylindrical bore 36 of the case.

Low friction thrust bearing support for the rotor is provided at the surface 37 of the header body where it is contacted by the small diameter shaft 38 on the end of the rotor. Engagement between the end of the shaft 38 and the surface 37 of the header body is normally maintained by a coil spring 39. However, in the event that the device is subjected to a jolt which would tend to move the rotor axially away from the header body, the extent of movement of the rotor is limited by the provision of a washer 41 secured in the housing and Whose surface 42 will stop movement of the rotor away from the header as soon as it is engaged by the rotor surface 43.

The washer 41 is held in place by a cylindrical sleeve 44 whose front end surface 46 is flush with. the shoulder 14 in the case, 11. An end cover 47 is provided and the rolling diaphragm 48 is sandwiched between a portion of the end cover and the shoulder 14 and surface 46. The rolled over end 49 of the case secures the end cover, the diaphragm, and the sleeve 44 in place. The end cover has an aperture 51 therein to allow transmission of pressure from outside of the housing onto the front surface 52 of the rolling diaphragm.

A piston 53 is located in the case and has a stem 54, the rear end portion of which is received in a cylindrical 3 cavity 56 in the front end of the rotor. The front end of the rotor has a vertical slot therein accommodating the piston pin 57. A helical slot 58 extends rearwardly from the lower end 59 of the vertical slot and a similar helical slot (not shown) extends rearwardly from the upper end 61 of the vertical slot.

The piston is provided with an outwardly extending flange 62 providing a shoulder 63 and a shoulder 64. A coil spring 66 is disposed between the shoulder 63 and the shoulder 67 of the washer 41. This spring pushes the piston toward the end cover 47 and the travel of the piston in that direction is stopped by the engagement of the shoulder 64 thereof with the shoulder 68 of the inwardly turned flange 69 of the sleeve 44. The inner frontal margin 71 of the sleeve flange 69 is curved as are the

surfaces

72 and 73 of the piston to accommodate easy rolling action of the diaphragm during axial movement of the piston. A slot 74 is provided in the piston and a guide pin 76 is secured in the case and received in the slot 74 to prevent rotation of the piston during axial movement thereof. The fit of the guide pin 76 in the case is such that no leakage of gas or liquid at this point will occur.

In addition to the coil spring 66, the coil spring 39 is provided and one end coil thereof abuttingly engages the front surface 43 of the rotor and the spring has an end tab 77 received in an aperture 78 in the rotor. The other end coil of the inner spring 39 abuttingly engages the surface 79 of the piston and the axially extending end portion 81 of the spring is received in the hole 82 in the piston. The spring 39 is wound so that the end portion 77 thereof received in the aperture 78 in the rotor exerts a rotational bias on the rotor in the direction of the arrow 83 in FIG. 2. Rotation of the rotor in that direction from the position shown in FIGS. 1 and 2 is prevented by the straight vertical slot in the front end of the rotor engaging the pin 57 of the piston. The piston cannot rotate because of the provision of the guide pin 76 in the slot 74.

An explosive lead charge 84 is provided in the wall of the case, extending from the rotor bore 36 thereof to the outer cylindrical surface thereof. This charge is sealed in the wall to prevent any leakage of gas or liquid between the interior and exterior of the case.

A detonator 86 is received in a cavity in the rotor and, when the rotor is in the safe position as shown in FIGS. 1 and 2, the rotor body shields the detonator from the lead charge 84. However, when the rotor rotates on its axis 87 to the armed position shown in FIG. 2A, an opening in the rotor wall accommodates communication between the detonator and the lead charge. It should be understood that the armed position of the rotor is achieved by rotation thereof through 90 from the position shown in FIGS. 1 and 2 to the position shown in FIG. 2A. The direction of rotation from the safe to the armed position is as shown by the arrow 88 in FIG. 2A.

A contact support plate 89 has a generally circular aperture 91 with a flat side 92 therein and is thereby received on the generally cylindrical boss 94 having a flat side 96, this boss being integral with the rotor body and shaft 38. The contact support plate 89 rests on the surface 97 at the end of the rotor body.

Electrical conductors

98 and 99 extend from the detonator to the

rivets

101 and 102, respectively. A first electrical contactor 103 has a bracket portion 104 secured by the rivet 101 to the boss 106 in the contact support plate 89. It also has a strip 107 extending therefrom and a strip 108 extending therefrom. This contactor member is typicaly made of a resilient electrically conductive material such as beryllium copper, for example. Also, the size of the member and its relationship to the rivet 101 and the inner cylindrical wall 109 of the contact support plate are such that slight deformation of the

strips

107 and 108 in the direction of the arrows 111 and 112 respectively, is necessary to get the member into position in the contact plate when it is mounted thereto by means of the rivet 101. This contactor is electrically connected to the conductor 98 (FIG. 1) by the rivet 101. An identical member 113 is secured to the contact support plate and to conductor 99 by the rivet 102. It is to be noted that in assembly, when the rotor is in the safe position shown in FIGS. 1 and 2, the curved end portion 114 of the member 103 engages the inner surface of the end portion of the strip 116 of the member 113. Likewise, the curved end portion 117 of the strip 118 of the member 113 engages the inner surface of the end portion of the strip 108 of the member 103. At any time that any portion of the member 103 engages any portion of the member 113, the

conductors

98 and 99 are electrically shorted outside of the detonator, and the detonator cannot be fired.

As shown in FIG. 1, the inner ends 22A and 23A of the connector pins 22 and 23 project into the cavity in the contact support plate 89. When the rotor is in the safe position, these ends do not contact anything inside the case. However, upon rotation of the rotor in the direction of the arrow 88 through from the position shown in FIGS. 1 and 2, the contact strip 107 will engage the pin end 22A and the contact strip 118 will engage the pin 23A. Any further rotation of the rotor will cause the strip 107 to be deflected from its initial position as shown in FIG. 2A. The same will occur to the strip 118. The end portion of each of these strips is, therefore, separated from contact with any portion of another strip, and the

conductors

98 and 99 to the detonators are unshorted. Conductor 98 is then electrically connected through the strip 107 to the pin 22 and conductor 99 is connected through the strip 118 to the pin 23. At this time, the arming and firing mechanism is armed and communication is provided from the detonator to the lead charge. The unit can then be fired from an external source connected to the cable 28.

The rotation of the rotor from the safe position to the armed position is accomplished by axial movement of the piston away from the end cover 47. This causes the piston pin 57 to move rearwardly in the helical slots which forces the rotor to turn in the direction of the arrow 88 in FIG. 2A. Rotation of the rotor will stop when it has rotated 90 because the helical slots are only long enough to permit this amount of rotation. Thus it is seen that the slots in the rotor co-operating with the pin in he piston limit the rotation of the rotor in both directions.

Axial movement of the piston away from the end cover 47 is caused by increases of hydrostatic pressure as the arming and firing mechanism descends to greater depths. The springs 39 and 66 can be selected and have the proper amount of initial load thereon necessary to begin rotation of the rotor only when some minimum predetermined depth is reached. Completion of rotation of the rotor to the armed position will occur at a greater depth which is also predetermined by the dimensions and values selected.

If, for any reason, the arming and firing mechanism is raised above the depth at which arming is desired, the springs move the piston toward the front cover 47 whereupon the pin moving forward in the helical slot turns the rotor away from the armed position. As mentioned previously, the spring 39 also assists the rotation in this direction. The spring 39 also normally provides the front thust support for the rotor.

In the use of the device of the present invention, the booster charge of the exposive train to be fired is posigzned over the external end of the explosive lead charge As mentioned previously, fail-safe features in such a device are desirable.

device according to the present invention. For example, the torsion-compression spring 39 resists turning of the rotor to the armed position. The compression spring 66 resists motion of the piston toward the rotor. The piston A number of these are found in the is normally made of a light-weight material and even dropping of the device on the end 19 will not cause the piston to overcome the force of the spring 66, so the rotor will not be turned to the armed position. The provision of the washer 41 to limit motion of the rotor toward the front end cover prevents rotation of the rotor in the event the device is dropped on the front end 4%. The mechanism is armed completely by hydrostatic pressure and not just unlocked.

Even if one of the springs happened to break, the rotor will still be held in the safe position by the other spring. In the unlikely event that one spring would break, the unit might arm at a shallower depth but still would be held in the safe position prior to that time. In the event of a leak into the housing through the diaphragm or some other place, arming would occur only upon reaching a greater depth than otherwise possible if no leak existed.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in charcter, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being had to the appended claims.

The invention claimed is:

l. A submersible arming and firing mechanism comprising:

a housing;

a rotor mounted in said housing for rotation between a safe position and an armed position;

means secured to said housing and limiting axial movement of said rotor;

an ignitable charge mounted in an exterior wall of said housing;

a detonator in said rotor, said detonator having first and second electrical conductors operable, when energized, to fire said detonator, said detonator being substantially enclosed by said rotor and shielded from said charge by said rotor when said rotor is 1n said safe position and exposed to said charge when said rotor is in said armed position;

first and second electrical contact springs mounted on said rotor, said first contact spring being secured to said first conductor and said second spring being secured to said second conductor, said first spring being normally self biased into electrical connection with said second conductor and said second spring being normally self biased into electrical connection with said first conductor at all times during rotation of said rotor in said housing until said rotor is in said armed position, to thereby electrically short said first and second conductors together outside of said detonator;

first and second electrical connector pins sealed to said housing and electrically insulated therefrom, said first pin being disposed in the path of movement of said first contact spring and engageable by said first contact spring during rotation of said rotor toward said armed position, said first contact spring being resiliently deformable by said first pin during further rotation of said rotor and separable by said first pin from electrical connection with said second conductor, and said second pin being disposed in the path of movement of said second contact spring and engageable by said second contact spring during rotation of said rotor toward said armed position, said second contact spring being resiliently deformable by said second pin during further rotation of said rotor and separable by said second pin from electrical connection with said first conductor, the separation of said second contact spring from said first conductor occurring when said rotor has rotated to said armed position;

a helical groove in said rotor;

a lightweight piston linearly movable in said housing in a direction parallel tothe axis of rotation of said rotor, said piston having a pin therein received in said groove and operable therein to rotate said rotor upon linear movement of said piston with respect to said rotor;

a rolling diaphragm sealed to said housing and engaging said piston and operable in response to pressure difference between the interior of said housing and hydrostatic pressure outside said housing to move said piston and thereby rotate said rotor in said housing toward said armed position when subjected to increases of hydrostatic pressure;

a first coil spring engaging said piston and said rotor and exerting a separating and rotational bias therebetween, the rotational bias being in a direction tending to rotate said rotor to said safe position;

a second coil spring engaging said piston and said housing and biasing said piston away from said rotor, said coil springs opposing motion of said piston caused by increasing hydrostatic pressure, the bias on said piston being established to prevent initial rotation of said rotor until said diaphragm is subjected to a first predetermined pressure differential, and to prevent rotation of said rotor to said armed position until said diaphragm is subjected to a second predetermined pressure differential, said coil springs being effective after said second pressure differential is reached to rotate said rotor from armed position when the pressure differential becomes less than said second predetermined amount to again disarm said mechanism;

and means on said housing for receiving and sealingly engaging an electrical connector plug having means thereon for connecting the plug to said pins and to an external electrical firing device to accommodate detonation of said charge from an external controller.

2. A submersible arming and firing mechanism comprising:

a housing;

an ignitable charge mounted in an exterior wall of said housing;

a detonator in said rotor, said detonator having first and sec-0nd electrical conductors operable, when energized, to fire said detonator, said detonator being exposed to said charge when said rotor is in said armed position;

a helical groove in said rotor;

a piston linearly movable in said housing in a direction parallel to the axis of rotation of said rotor, said piston having a pin therein received in said groove and operable therein to rotate said rotor upon linear movement of said piston with respect to said rotor;

a diaphragm sealed to said housing and engaging said piston and operable in response to pressure difference between the interior of said housing and hydrostatic pressure outside said housing to move said piston and thereby rotate said rotor in said housing toward said armed position when subjected to increases of hydrostatic pressure;

a spring biasing said piston away from said rotor, said piston biasing spring opposing motion of said piston caused by increasing hydrostatic pressure, the bias on said piston being established to prevent rotation of said rotor to said armed position until said diaphragm is subjected to a predetermined pressure differential, said piston biasing spring being effective after said predetermined pressure difierential is reached to rotate said rotor from armed position when the pressure differential becomes less than said predetermined amount to again disarm said mechanism;

and means on said housing for receiving an external electrical connector plug having means thereon for connecting the plug to said pins and to an external electrical firing device to accommodate detonation of said charge from an external controller.

3. In a submersible arming and firing mechanism, the

combination comprising:

a housing;

an ignitable charge mounted in an exterior wall of said housing;

a detonator in said rotor, said detonator having first and second electrical conductors operable, when energized, to fire said detonator, said detonator being exposed to said charge when said rotor is in said armed position;

an electrical contact spring mounted on said rotor, said contact spring being secured to said first conductor and said spring being normally self biased into electrical connection with said second conductor at all times during rotation of said rotor in said housing until said rotor is in said armed position to thereby electrically short said first and second conductors together outside of said detonator;

an electrical connector pin sealed to said housing and electrically insulated therefrom, said pin being disposed in the path of movement of said contact spring and engageable by said contact spring during rotation of said rotor toward said armed position, said contact spring being resiliently deformable by said pin during further rotation of said rotor and separable by said pin from electrical connection with said second conductor, the separation of said contact spring from said first conductor occurring when said rotor has rotated to said armed position;

a piston linearly movable in said housing in a direction parallel to the axis of rotation of said rotor, said piston and rotor having means thereon operable to rotate said rotor upon linear movement of said piston with respect to said rotor;

a spring biasing said piston away from said rotor, said iston biasing spring opposing motion of said piston caused by increasing hydrostatic pressure, the bias on said piston being established to prevent rotation of said rotor to said armed position until said diaphragm is subjected to a predetermined pressure differential, said piston biasing spring being effective after said predetermined pressure diiferential is reached to rotate said rotor from armed position when the pressure differential becomes less than said predetermined amount to again disarm said mechanism;

and means on said housing for receiving an electrical connector plug having means thereon for operatively connecting the plug to said pin and to said second conductor and to an external electrical firing device to accommodate detonation of said charge from an external controller.

4. In a submersible arming and firing mechanism, the

combination comprising:

a housing;

an ignitable charge mounted in an exterior wall of said housing;

a movable electrical contactor mounted on said rotor,

said contactor being connected to said first conductor and said contactor being normally biased into electrical connection with said second conductor at all times during rotation of said rotor in said housing until said rotor is in said armed position to thereby electrically short said first and second conductors together outside of said detonator;

a contactor sealed to said housing and electrically insulated therefrom, said sealed contactor being disposed in the path of movement of said movable contactor and engageable by said movable contactor during rotation of said rotor toward said armed position, said movable contactor being movable with respect to said rotor and against the bias thereon by engagement with said sealed contactor during further rotation of said rotor and separable by said sealed contactor from electrical connection with said second conductor, the separation of said movable contactor from said first conductor occurring when said rotor has rotated to said armed position;

a spring biasing said piston away from said rotor, said piston biasing spring opposing motion of said piston caused by increaing hydrostatic pressure, the bias on said piston being established to prevent rotation of said rotor to said armed position until said diaphragm is subjected to a predetermined pressure differential, said piston biasing spring being effective after said predetermined pressure differential is reached to rotate said rotor from armed position when the pressure difierential becomes less than said predetermined amount to again disarm said mechanism;

and means on said housing for receiving an electrical connector plug having means thereon for operatively connecting to said sealed contactor and to said second conductor and to an external electrical firing device to accommodate detonation of said charge from an external controller.

5. In a submersible arming and firing mechanism the combination comprising:

a housing;

a detonator in said rotor, said detonator having first and second electrical conductors operable, when energized, to fire said detonator;

a movable electrical contact-or mounted on said rotor,

said contactor 'being connected to said first conductor and said contactor being normally biased into electrical connection with said second conductor at all times during rotation of said rotor in said housing until said rotor is in said armed position, to thereby electrically short said first and second conductors together outside of said detonator;

a second contactor disposed in the path of movement of said movable contactor and engageable by said movable contactor during rotation of said rotor toward said armed position, said movable contactor being movable with respect to said rotor and against the bias thereon by engagement with stationary means in said housing during rotation of said rotor and separable by said stationary means from electrical connection with said second conductor, the separation of said movable contactor from said second conductor occurring when said rotor has rotated to said armed position;

and a spring biasing said piston away from said rotor, said piston biasing spring opposing motion of said piston caused by increasing hydrostatic pressure, the bias on said piston being established to prevent rotation of said rotor to said armed position until said diaphragm is subjected to a predetermined pressure difierential, said piston biasing spring being elfective after said predetermined pressure diiferential is reached to rotate said rotor from armed posi tion when the pressure differential becomes less than said predetermined amount to again disarm said mechanism.

References Cited by the Examiner UNITED STATES PATENTS 2,748,704 6/1956 Dinsmoor 10216 X 2,827,850 3/1958 Muzzey l0216 2,974,597 3/ 196 1 Hesson 10270.2 2,994,272 8/1961 Saunderson 102-76 X 3,000,315 9/1961 Anastasia et al. 102-76 X BENJAMIN A. BORCHELT, Primary Examiner.

FRED C. MATTERN, JR., Examiner.

V. R. PENDEGRASS, Assistant Examiner.

Claims

1. A SUBMERSIBLE ARMING AND FIRING MECHANISM COMPRISING: A HOUSING; A ROTOR MOUNTED IN SAID HOUSING FOR ROTATION BETWEEN A SAFE POSITION AND AN ARMED POSITION; MEANS SECURED TO SAID HOUSING AND LIMITING AXIAL MOVEMENT OF SAID ROTOR; AN IGNITABLE CHARGE MOUNTED IN AN EXTERIOR WALL OF SAID HOUSING; A DETONATOR IN SAID ROTOR, SAID DETONATOR HAVING FIRST AND SECOND ELECTRICAL OPERABLE, WHEN ENERGIZED, TO FIRE SAID DETONATOR, SAID DETONATOR BEING SUBSTANTIALLY ENCLOSED BY SAID ROTOR AND SHIELDED FROM SAID CHARGE BY SAID ROTOR WHEN SAID ROTOR IS IN SAID SAFT POSITION AND EXPOSED TO SAID CHARGE WHEN SAID ROTOR IS IN SAID ARMED POSITION; FIRST AND SECOND ELECTRICAL CONTACT SPRINGS MOUNTED ON SAID ROTOR, SAID FIRST SPRING BEING SECURED TO SAID FIRST CONDUCTOR AND SAID SECOND SPRING BEING SECURED TO SAID SECOND CONDUCTOR, SAID FIRST SPRING BEING NORMALLY SELF BIASED INTO ELECTRICAL CONNECTION WITH SAID SECOND CONDUCTOR AND SAID SECOND SPRING BEING NORMALLY SELF BIASED IN ELECTRICAL CONNECTION WITH SAID FIRST CONDUCTOR AT ALL TIMES DURING ROTATION OF SAID ROTOR IN SAID HOUSING UNTIL SAID ROTOR IS IN SAID ARMED POSITION, TO THEREBY ELECTRICALLY SHORT SAID FIRST AND SECOND CONDUCTORS TOGETHER OUTSIDE OF SAID DETONATOR; FIRST AND SECOND ELECTRICAL CONNECTOR PINS SEALED TO SAID HOUSING AND ELECTRICALLY INSULATED THEREFROM, SAID FIRST PIN BEING DISPOSED IN THE PATH OF MOVEMENT OF SAID FIRST CONTACT SPRING AND ENGAGEABLE BY SAID FIRST CONTACT SPRING DURING ROTATION OF SAID ROTOR TOWARD SAID ARMED POSITION, SAID FIRST CONTACT SPRING BEING RESILIENTLY DEFORMABLE BY SAID FIRST PIN DURING FURTHER ROTATION OF SAID ROTOR AND SEPARABLE BY SAID FIRST PIN FROM ELECTRICAL CONNECTION WITH SAID SECOND CONDUCTOR, AND SAID SECOND PIN BEING DISPOSED IN THE PATH OF MOVEMENT OF SAID SECOND CONTACT DURING ROENGAGEABLE BY SAID SECOND CONTACT SPRING DURING ROTATION OF SAID ROTOR TOWARD SAID ARMED POSITION, SAID SECOND CONTACT SPRING BEING RESILIENTLY DEFORMABLE BY SAID SECOND PIN DURING FURTHER ROTATION OF SAID ROTOR AND SEPARABLE BY SAID SECOND PIN FROM ELECTRICAL CONNECTION WITH SAID FIRST CONDUCTOR, THE SEPARATION OF SAID SECOND CONTACT SPRING FROM SAID FIRST CONDUCTOR OCCURING WHEN SAID ROTOR HAS ROTATED TO SAID ARMED POSITION; A HELICAL GROOVE IN SAID ROTOR; A LIGHTWEIGHT PISTON LINEARLY MOVABLE IN SAID HOUSING IN A DIRECTION PARALLEL TO THE AXIS OF ROTATION OF SAID ROTOR, SAID PISTON HAVING A PIN THEREIN RECEIVED IN SAID GROOVE AND OPERABLE THEREIN TO ROTATE SAID ROTOR UPON LINEAR MOVEMENT OF SAID PISTON WITH RESPECT TO SAID ROTOR; A ROLLING DIAPHRAGM SEALED TO SAID HOUSING AND ENGAGING SAID PISTON AND OPERABLE IN RESPONSE TO PRESSURE DIFFERENCE BETWEEN THE INTERIOR OF SAID HOUSING AND HYDROSTATIC PRESSURE OUTSIDE SAID HOUSING TO MOVE SAID PISTON AND THEREBY ROTATE SAID ROTOR IN SAID HOUSING TOWARD SAID ARMED POSITION WHEN SUBJECTED TO INCREASES OF HYDROSTATIC PRESSURE; A FIRST COIL SPRING ENGAGING SAID PISTON AND SAID ROTOR AND EXTERTING A SEPARATING AND ROTATIONAL BIAS THEREBETWEEN, THE ROTATIONAL BIAS BEING IN A DIRECTION TENDING TO ROTATE SAID ROTOR TO SAID SAFE POSITION; A SECOND COIL SPRING ENGAGING SAID PISTON AND SAID HOUSING AND BIASING SAID PISTON AWAY FROM SAID ROTOR, SAID COIL SPRINGS OPPOSING MOTION OF SAID PISTON CAUSED BY INCREASING HYDROSTATIC PRESSURE, THE BIAS ON SAID PISTON BEING ESTABLISHED TO PREVENT INITIAL ROTATION OF SAID ROTOR UNTIL SAID DIAPHRAGM IS SUBJECTED TO A FIRST PREDETERMINED PRESSURE DIFFERENTIAL, AND TO PREVENT ROTATION OF SAID ROTOR TO SAID ARMED POSITION UNTIL SAID DIAPHRAGM IS SUBJECTED TO A SECOND PREDETERMINED PRESSURE DIFFERENTIAL, SAID COIL SPRINGS BEING EFFECTIVE AFTER SAID SECOND PRESSURE DIFFERENTIAL IS REACHED TO ROTATE SAID ROTOR FROM ARMED POSITION WHEN THE PRESSURE DIFFERENTIAL BECOMES LESS THAN SAID SECOND PREDETERMINED AMOUNT TO AGAIN DISARM SAID MECHANISM; AND MEANS ON SAID HOUSING FOR RECEIVING AND SEALINGLY ENGAGING AN ELECTRICAL CONNECTOR PLUG HAVING MEANS THEREON FOR CONNECTING THE PLUG TO SAID PINS AND TO AN EXTERNAL ELECTRICAL FIRING DEVICE TO ACCOMMODATE DETONATION OF SAID CHARGE FROM AN EXTERNAL CONTROLLER.