GB Patent 955598 - Improvements in or relating to underwater lowering devices

Description

PATENT SPECIFICATION

DRAWINGS ATTACHED 955598 M, 4 a Date of Application and filing Complete Specification: July 28, 1960.

It O No 26302/60.

U t o 5 M 1 j Application made in United States of America (No 830,344) on July 29, 1959.

Complete Specification Published: April 15, 1964.

\ Crown Copyright 1964.

Index at acceptance:-F 2 H ( 21 B, 23 A 3 A, 24 A 2 A, 24 DIA, 24 D 1 B, 24 D 2 B, 24 D 3 X, 25 A) International Classification:-11 02 g COMPLETE SPECIFICATION

Improvements in or relating to Underwater Lowering Devices We, WESTERN ELECTRIC COMPANY, INCORPo RATED, of 195, Broadway, New York City, New York State, United States of America, a Corporation of the State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:This invention relates to a device for lowering an object beneath the surface of a body of water and, more particularly, to an underwater lowering device having improved means for securely retaining an object until it is released automatically in response to the completion of the lowering process.

The invention is particularly applicable for use with equipment employed in laying or repairing ocean cable For example, when an ocean cable has been damaged, the cable must be pulled aboard a ship in order to be repaired These repairs usually involve excision of the injured portion, after which the undamaged ends of the cable are spliced together This forms a long bight in the cable extending from the deck of the repair ship to the floor of the ocean which, in some instances might be at a depth of two or more miles.

Such a long cable bight should not be simply pushed overboard and allowed to fall back into the ocean without any guidance because the tension inherent in the cable would cause it to become snarled and tangled and this might create new injuries in the cable Therefore, it is desirable that means be employed for lowering a spliced cable bight from the ship to the ocean floor in a manner such that the speed of descent can be readily controlled at all times.

In shallow water, this can be accomplished by means of the so-called " double-line " technique This method comprises looping or doubling a line around a cable, lowering the lPrice 4 s 6 d l cable by means of this loop until the bed of the water is reached, then throwing one end of the line into the water, and, finally, hauling the entire length of line aboard the ship with one-half of the line sliding underneath the cable bight.

The " double-line " technique is not practical for use in deep water for various reasons, such as the extremely long length of line that would be required Instead, it would be preferable to use a single line with one end supporting the cable bight in such a manner that this end of the line could be readily released from the cable when the ocean floor is reached.

According to the invention, a device for lowering an object beneath the surface of a body of water comprises holding means for retaining the object during lowering, releasing means including a plunger for effecting release of the object from the holding means, a control device for inhibiting motion of the plunger until a predetermined portion of the lowering process is completed, the releasing means then remaining in the enabled condition until release of the object is to be effected, and means for operating the enabled plunger including a member having a plurality of arms extending beneath the bottom of the device and adapted to be moved in response to contact with the bed of the body of water whereby movement of the said member produces movement of the plunger to effect release of the said object.

In the event of a failure of the releasing apparatus, emergency equipment may be provided for effecting the release of the object.

The lowering device may further include signalling means for producing an indication of the operation of the releasing apparatus.

The invention is more fully discussed in connection with the following detailed description of an embodiment thereof taken in conjunction with the accompanying drawings in which:

GI) ell_ Fig 1 is a pictorial representation of one embodiment of an underwater lowering device constructed in accordance with this invention and illustrating the manner in which it retains and supports a cable bight; Fig 2 is a sectional view of the underwater lowering device showing the locations and relationships of its components; Fig 3 is a side view of the control or arming mechanism together with a portion of the releasing apparatus and illustrates the manner in which the releasing apparatus becomes enabled for subsequent operation; and Fig 4 is a schematic view of the components of the underwater lowering device indicating in particular the manner of operation of the releasing apparatus and the signaling means.

In Fig 1, an embodiment of an underwater lowering device constructed in accordance with this invention is represented as including a cylindrical body member 1 which also functions as a housing for other components of this lowering device The body member 1 may be made of any suitable material, such as iron The top portion of the body member 1 is provided with a rotatable swivel 2 having an eye 3 to which is fastened the lower end of a rope 4 the upper end of which is secured to a winch carried on a ship so that the device can be raised or lowered at a rate of speed controlled by an operator on the ship.

Another eye 5 is attached to the bottom of the body member 1 for supporting a pelican hook 6 which is pivotally mounted thereon so that it can move from a closed position, shown in Fig 2, to an open position, shown in Fig 4 As is indicated in Fig 1, during the underwater lowering process, the pelican hook 6 is normally held in its closed position by a catch 7 It is to be noted that, for purposes of illustration, the catch 7 is shown in Fig 1 to be positioned slightly below the bottom of the body member 1.

While this arrangement is operable, it is preferable for the catch 7 to be located within a recess formed in the bottom of the body member 1 as is shown in Figs 2 and 4.

When the hook 6 is in its closed position, it supports a short chain 8 from which a relatively long sleeve member 9 is suspended by means of a bolt 10 The sleeve member 9 is formd in the shape of a trough for receiving therein an ocean cable 11 The ends of the sleeve member 9 are somewhat flared so that they will not cut or scrape the cable 11 It is to be noted that the longitudinal axis of the sleeve member 9 is slightly curved to conform to the curve of the cable 11 when it is hanging therefrom in the form of a bight.

The pelican hook 6 and the chain 8 are encircled by-a hoop member 12 of relatively large diameter having a plurality of bracketlike arms 13 These arms 13 pass through slots 14 in the body member 1 and are supported thereby in the manner shown in Fig.

2 It is to be noted that each of the slots 14 has a vertical axis which is made relatively 70 long in order to permit the arms 13 to move or tilt upward as is indicated in Fig 4 Thus, when the underwater lowering process is completed, the hoop member 12 will rest on the ocean floor thereby causing its arms 13 to 75 move or tilt with respect to the body member 1.

During the underwater descent, releasing apparatus, described hereinafter, will become conditioned for operation by an arming or 80 enabling device attached to a large nut 15 and adapted to be actuated by hydrostatic pressure applied through a hole 16 in the body member 1 The subsequent movement of the arms 13 will cause the releasing 85 apparatus to move the catch 7 out of engagement with the pelican hook 6 At this time, a signalling device, enclosed by a ring 19, will produce a signal that is indicative of the operation of the releasing apparatus If the 90 releasing apparatus should fail to operate emergency equipment which includes a hydrophone 17, can be operated to effect the removal of the catch 7 In either case, the removal of the catch 7 enables the pelican 95 hook 6 to pivot to its open position thereby allowing the chain 8 to slide off the hook 6.

The lowering device can now be pulled up to the ship while leaving the chain 8, the sleeve member 9, and the cable 11 on the 100 ocean floor When the lowering device has been pulled aboard the ship, a plunger i S can be operated to restore the releasing apparatus to its normal condition.

The internal components of the lowering 105 device will now be described with particular reference to Fig 2 in which it can be seen that the hoop-supporting arms 13 are connected together to form an integral junction 21 having a stud 22 projecting upward there 110 from Another stud 23 is positioned above the stud 22 and is located beneath a flange 24 on which a swivel 2 is rotatably mounted.

These studs 22 and 23 serve to retain the ends of a coiled spring 25 which is designed to 115 push down on the juncteion 21 so as normally to keep the arms 13 at the bottom of the slots 14.

As is illustrated in Fig 2, the arms 13, the spring 25, and the studs 22 and 23 are 120 located in a hemispherical cavity 26 in the upper portion of the body member 1.

Although Fig 2 shows only two slots 14 opening into this cavity 26, it is to be understood that two other similar slots 14 also 125 open into the cavity 26, one behind the spring and one in front of it Each of these two last-mentioned slots 14 admits an arm 13, one extending from the rear of the junction 21 and the other projecting in front of it 130 955,598 force it in an upward direction so as to release the catch 7 as is represented in Fig.

4 However, this upward movement of the lower toggle link 35 is prevented by the pins 38 when the plunger 18 is in the position 70 shown in Fig 2.

The plunger 18 is designed to slide in and out of the body member 1 with its extent of travel being limited in one direction by the contact of its head with the outside sur 75 face of the body member 1 as is shown in Fig 2 In order to limit its movement in the other direction, the plunger 18 is provided with two slots 40 designed to receive therein respectively associated pins 41 attached to 80 the body member 1 Thus, when the plunger 18 is moved to its position shown in Fig 4, it will slide along the pins 41 until the right ends of the slots 40 come into contact with the pins 41 It can be understood that this 85 combination of slots 40 and pins 41 also functions as guiding means for preventing any irregular up-and-down motion of the plunger 18.

In order to move the plunger 18 from its 90 position shown in Fig 2 to its position shown in Fig 4, the plunger 18 is equipped with a tooth 42 which, under a condition described hereinafter, is adapted to be engaged by the roller 33 on the pawl 32 Accordingly, when 95 the arms 13 become tilted, their central eye 27 will be raised up thereby pulling the associated link 29 upward This will cause the bell-crank 30 to swing upward about its pivot 31 with the result that the pawl 32 will 100 be shoved to the left If it is assumed that the roller 33 is now in contact with the tooth 42, then the plunger 18 will also be moved to the left This movement of the plunger 18 will cause its pins 38 to force the toggle links 105 and 36 into their operated positions shown in Fig 4 where they will be held by the " over-the-center " action of the spring 39.

In moving to its operated position, the lower toggle link 35 will pull the catch 7 upward 110 thereby releasing the pelican hook 6 and allowing it to swing downward to its open position This will permit the chain 8 to slide off the hook 6 thus terminating the retention of the cable 11 115 However, it can be understood that it would not be desirable to allow the roller 33 to be normally in contact with the tooth 42 because the equipment would then be subjected to the hazard of being operated pre 120 maturely with the result that the cable 11 might be released before it had been lowered to a safe depth For example, the hoop 12 might be unintentionally tilted during the process of lowering the device over the side 125 of the ship Also, during the descent of this underwater lowering device, the hoop 12 might be accidentally actuated by striking against some submerged object Therefore, in order to prevent premature release of the 130 as is indicated by its cross-section 131.

This construction permits the arms 13 to tilt in any one of four directions For example, the contact between the hoop 12 and the ocean floor may be such as to force the left arm 13 upward, as is indicated in Fig 4.

The extent of this upward movement is limited by the engagement of this arm 13 with the top of its respectively associated slot 14 During this tilting movement, the assembly of the arms 13 pivots at the point where the right arm 13 engages the bottom of its associated slot 14 Due to the flexibility of the coiled spring 25, the junction 21 of the arms 13 is permitted to rise upward, as is represented in Fig 4 If the hoop 12 should settle in a level position without tilting its arms 13, then the body member 1 would continue to move downward with the spring 25 becoming compressed until the upper ends of the slots 14 came to rest upon the arms 13 This relative movement between the body member 1 and the arms 13 will cause the junction 21 to move to substantially the same position that it would be in if the arms 13 had been tilted.

Referring again to Fig 2, it can be seen that an eye 27 is located under the stud 22 and is formed integrally with the junction 21 of the four arms 13 This eye 27 is loosely received within a well-like cavity 28 in the body member 1 The upper portion of the cavity 28 is flared so as to permit the eye 27 to be easily dragged thereover when the arms 13 are tilted in the manner shown in Fig 4 The eye 27 holds the upper end of a link member 29 which is free to rotate therein as is indicated in Fig 4 The lower end of the link member 29 is rotatably attached to a bell-crank 30 which is pivotally attached to the body member 1 by means of a pivot 31 The lower portion of the bellcrank 30 carries a pawl 32 having its right end pivotally attached to the bell-crank 30 and having a roller 33 rotatably mounted on its left end This pawl 32 is normally forced downward by a spring 34 for a purpose that is explained hereinafter.

As was stated above, the pelican hook 6 is held in its closed position by a catch 7 as is shown in Fig 2 The catch 7 has its right end pivotally attached to the body member 1 and has its left end rotatably attached to the bottom end of a toggle linkage comprising a lower toggle link 35 rotatably joined to an upper toggle link 36 which has its top end pivotally attached to the body member 1 The bottom end of the upper toggle link 36 is prevented from swinging to the right by means of a stop 37 The movement of the upper portion of the lower toggle link 35 is controlled by two pins 38 carried on the plunger 18 previously mentioned above This lower toggle link 35 is normally biased by a coiled spring 39 which tends to 955,598 cable 11 it is preferable to normally keep the releasing apparatus in a disabled or ineffectual condition by means of a control or arming device which will be automatically operated at some preassigned depth under water for putting the releasing apparatus in an enabled condition for subsequent operation.

One embodiment of an arming device in accordance with this invention is designed to be operatively responsive to an assigned amount of hydrostatic pressure Accordingly, it utilizes a pressure-sensitive instrumentality represented in the drawings by a bellows 43 which may conveniently be made of molded rubber forming a water-tight chamber having a flexible circumferential ridge 44 In order to provide a strong backing plate for the bellows 43, the previously mentioned large nut 15 has a concavity formed therein of such size as to snugly receive the right half of the bellows 43 This half of the bellows 43 is preferably firmly bonded to the nut 15 so that the bellows 43 and the nut 15 can be handled as a unit.

The bellows 43 is received within a hollow protuberance 45 formed on one side of the body member 1 The external opening of this protuberance 45 is screw-threaded so that the nut 15 can be securely retained therein It is to be noted that, when the nut 15 is fastened in place, the bellows 43 does not completely fill the interior of the protuberance 45 Instead, the interior of the protuberance 45 is made substantially larger than the bellows 43 so as to form a chamber 46 A hole 16, previously mentioned above, extends from the outside surface of the protuberance 45 into the chamber 46 for the purpose of admitting water thereto so that the surrounding hydrostatic pressure will be applied to the bellows 43 during the underwater lowering process.

The left half of the bellows 43 has a small metallic plate 47 securely bonded thereto for movement therewith The plate 47 holds the right end of a rod 48 which is attached thereto by means of a swivel 49 The reason for using the swivel 49 is that, since the bellows 43 is bonded to the nut 15, the bellows 43 will turn whenever the nut 15 is turned on its threads but, due to the swivel connection 49, the rod 48 will not turn This rod 48 is slidably received within a slot formed in the body member 1 which prevents any irregular up-and-down motion of the rod 48.

The extent of the sliding movement of the rod 48 is controlled by the bellows 43 Thus, when the bellows 43 is in its fully expanded condition, the rod 48 will be in the position shown in Fig 2 When the bellows 43 becomes compressed as is described hereinafter, the rod 48 will be pulled into the position shown in Fig 4 It is to be noted that the left end of the rod 48 is slanted for a purpose that is explained hereinafter.

As is shown in Fig 2, when the bellows 43 is in its normally uncompressed condition, the left end of the rod 48 extends under the roller 33 on the pawl 32 and abuts against the tooth 42 on the plunger 18 It can be 70 understood that, in moving to this position, the slanted end of the rod 48 will slide under the roller 33 and will force the pawl 32 upward against the bias exerted by the spring 34 Thus, when the rod 48 is in this position, 75 it holds the roller 33 and the pawl 32 out of engagement with the tooth 42 thereby locking them in an ineffectual condition.

This serves to disable the releasing apparatus in a manner that will now be explained 80 Assuming that the hoop 12 is moved so as to cause the arms 13 to tilt, then the eye 27 will be moved upward as is shown in Fig 4.

This causes the link 29 to pull the bell-crank upward about its pivot 31 as is also shown 85 in Fig 4 In so moving, the bell-crank 30 will shove the pawl 32 and the roller 33 toward the left Since the roller 33 is now held out of engagement with the tooth 42, the movement of the pawl 32 and the roller 33 90 will be ineffectual at this time to accomplish any useful purpose Thus, the arming equipment, comprising the bellows 43 and the rod 48, functions to disable the releasing apparatus with the result that the pelican hook 6 95 is locked in its closed position so that the cable 11 cannot be prematurely released.

As was stated above, the purpose of the arming mechanism is to prevent the cable 11 from being prematurely released due to ld accidental operation of the releasing apparatus It can be understood that such unintentional actuation of the releasing apparatus would be most liable to occur during the procedure of moving the lowering device from 105 the ship and placing it in the ocean After tht device has been immersed in the ocean and has been lowered to a safe distance beneath the ship, there would be only a slight chance of the hoop 12 and the arms 13 be 110 coming accidentally operated during the subsequent lowering process Therefore, as a practical matter, the releasing apparatus can be unlocked and placed in its efficacious condition at some empirically selected depth, 115 such as 33 fathoms Accordingly, when this selected partial extent of the underwater lowering process has been completed, the arming mechanism is designed to become operatively responsive for the purpose of un 120 locking the releasing apparatus and putting it in an enabled condition This can be conveniently accomplished by so selecting the thickness and quality of the rubber forming the bellows 43 that it will become fully com 125 pressed in response to that amount of hydrostatic pressure which corresponds to the particular depth that has been selected.

This objective is attained in a manner that will now be explained It can be understood 130 955,598 ing against the glass ball 51 by means of a 65 coiled spring 54.

When the releasing apparatus is operated, the plunger 18 is moved to the left, as was explained above, thereby causing its pins 38 to snap the toggle links 35 and 36 into the 70 position shown in Fig 4 In moving to this position, the upper toggle link 36 will strike the head of the plunger 53 with sufficient force to cause its pointed end to implode the glass ball 51 as is represented in Fig 4 75 This produces a sound signal which can be detected by a hydrophone at the ship, thus providing an indication of the actuation of the releasing apparatus.

In the event the releasing apparatus should 80 fail to operate, it can be understood that, instead of hauling the lowering device and the cable 11 back up to the ship, it would be preferable to employ some form of emergency equipment for effecting the re 85 lease of the cable 11 Therefore, the lowering device is provided with such emergency equipment which, in this embodiment of the invention, includes the hydrophone 17 The output terminals of the hydrophone 17 are 90 connected to a relay 55 which controls an energizing circuit leading from a battery 56 to a solenoid 57 This solenoid 57 is provided with a large armature 58 which is securely mounted on an extension 59 of the 95 plunger 18 for movement therewith.

This emergency equipment is designed to operate in response to the reception by the hydrophone 17 of an assigned low frequency sound signal transmitted under water from 100 the ship When this signal is received at the hydrophone 17, it is converted into electric energy in a manner well known to those skilled in the art The electric energy thus produced is applied to the relay 55 which 105 responds by operating its armature to close the energizing circuit of the solenoid 57.

Upon being thus energized, the solenoid 57 moves its armature 58 from the position shown in Fig 2 to the Position shown in 110 Fig 4 Since the armature 58 is attached to the extension 59 of the plunger 18, this movement of the armature 58 produces a corresponding movement of the plunger 18 which, in turn, effects the actuation of the 115 toggle links 35 and 36 thereby operating the catch 7 and releasing the cable 11.

It is to be understood that the relay 55 remains energized only during the time that the hydrophone 17 is receiving the signal from 120 the ship When this signal is terminated, the relay 55 ceases to be energized and consequently releases its armature thereby opening the energizing circuit of the solenoid 57.

Although the solenoid 57 now becomes de 125 energized, its armature 58 remains in its operated position until the plunger 18 is manually returned to the position shown in that, when the lowering device is first immersed in the ocean, sea water enters the hole 16 and fills the chamber 46 During the process of descent, the instantaneous hydrostatic pressure surrounding the lowering device will be transmitted through the hole 16 and into the chamber 46 where it will be applied to the bellows 43 The right half of the bellows 43 is unable to yield in response to this pressure because it is securely bonded to the nut as was described above However, the left half of the bellows 43 is able to yield with the result that it becomes compressed by the hydrostatic pressure and is gradually forced inward toward the nut 15 while carrying with it the metallic plate 47 and the rod 48 The extent of this travel is terminated when the bellows 43 becomes fully compressed as is shown in Figs 3 and 4.

Referring now to Fig 3, it can be seen that the compression of the bellows 43 has caused the rod 48 to move a sufficient distance for it to become withdrawn from its former position under the roller 33 Accordingly, this permits the spring 34 to force the pawl 32 downward thereby bringing the roller 33 into contact with the plunger 18 and into engagement with the tooth 42 Now, when the bell-crank 30 is moved upward about its pivot 31 in response to the upward movement of the link 29 in the manner described above, this motion of the bell-crank will shove the pawl 32 toward the left with the result that its roller 33 will push against the tooth 42 and will consequently slide the plunger 18 toward the left as is represented in Fig 4 This actuates the toggle links 35 and 36 and causes them to move the catch 7 upward thereby terminating the retention of the cable 11 by the pelican hook 6 as was explained above.

When the cable 11 is thus released from the pelican hook 6, it is desirable that personnel on board the ship be informed of the operation of the releasing mechanism Accordingly, the lowering device is equipped with signaling means for this purpose One embodiment of such signaling means includes a glass ball 51 located within a cavity in the body member 1 and retained therein by means of the ring 19 that was previously mentioned above This ring 19 is screwthreaded so that it can be readily removed from the body member 1 It is also provided with a central bore 52 having a somewhat smaller diameter than the glass ball 51 The signaling means further comprise a small plunger 53 that is slidably mounted in the body member 1 with one end near the upper toggle link 36 as is indicated in Fig 2 The other end of the plunger 53 is positioned close to the glass ball 51 and is so shaped as to form a point This pointed end of the plunger 53 is normally prevented from press955,598 Fig 2 as is described hereinafter.

Considering now the over-all manner in which the lowering device of this invention is used, let it be assumed that the device is on the deck of a ship with its components in the condition illustrated in Fig 2 in preparation for the lowering process In order for a cable bight 11 to be retained by this device, tde bolt 10 is withdrawn so as to detach the sleeve 9 from the chain 8 A portion of the cable 11 is then placed in the longitudinal trough formed in the sleeve 9.

After this has been done, the bolt 10 is replaced so that the sleeve 9 is again suspended from the chain 8 This results in the cable 11 being held in the manner shown in Fig 1.

The lowering device and the cable 11 are now hoisted above the deck and are swung over the side of the ship They are then lowered into the ocean by means of the rope 4 which has its rate of movement controlled by a winch During these operations, the hoop 12 is liable to become accidentally tilted, such as by being bumped against the side of the ship However, the cable 11 will remain held by the lowering device because its releasing apparatus is disabled at this time due to the arming mechanism being in its unoperated condition as is shown in Fig 2.

When the lowering device is immersed in the ocean, sea water will enter through the hole 16 into the chamber 46 surrounding the bellows 43 During the underwater descent of the lowering device, the surrounding hydrostatic pressure will gradually increase with the result that the bellows 43 will become compressed as was explained above.

Assuming that the thickness and quality of the rubber forming the bellows 43 have been so selected that the bellows 43 will be fully compressed at the assigned depth of 33 fathoms, then, when this depth is reached, the rod 48 will be withdrawn from under the roller 33 thereby enabling it to engage the tooth 42 and thus arming the releasing apparatus In other words, the arming mechanism, comprising the bellows 43 and therod 48, responds to the completion of this selected partial extent of the underwater lowering process by putting the releasing apparatus in an enabled condition for subsequent operation.

The releasing apparatus will remain in its enabled condition until either the hoop 12 is actuated or the relay 55 is energized Considering firstly the actuation of the hoop 12, it can be understood that, when the cable bight 11 reaches the ocean floor, it assumes a position compatible with any tension or stress in which it may be subjected Any tendency to form an upright loop or kink of the portion of the cable within the sleeve 9 is prevented by the hoop 12 which continues to descend until it rests over the cable 11 and the sleeve 9 upon the ocean floor Since this contact between the hoop 12 and the combination of the ocean floor, the sleeve 9, and the cable 11 is ordinarily not level, it will usually cause the arms 13 to become tilted so as to pull the link 29 upward as is 70 represented in Fig 4.

However, it is possible that the hoop 12 might settle squarely on the ocean floor without tilting its arms 13 In this event, the body member 1 would continue to move 75 downward with the spring 25 becoming compressed until the upper ends of the slots 14 are supported upon the arms 13 This relative motion between the body member 1 and the arms 13 causes substantially the same 80 upward movement of the link 29 as that described above.

Thus, in either event, the link 29 is pulled upward so as to move the bell-crank 30 about its pivot 31 as is shown in Fig 4 85 Since the roller 33 is now in contact with the tooth 42, the plunger 18 is consequently pushed to the left Although the extension 59 of the plunger 18 carries the armature 58 inside the solenoid 57, this does not serve 90 any useful purpose at this time The leftward movement of the plunger 18 snaps the toggle links 35 and 36 into their operated positions shown in Fig 4 This causes the lower toggle link 35 to pull the catch 7 out of engagement 95 with the pelican hook 6 which accordingly swings downward to its open position thereby releasing the chain 8, the sleeve 9, and the cable 11 At the same time, the upward movement of the upper toggle link 36 im 100 plodes the glass ball 51 to produce a signal indicative of the actuation of the releasing apparatus.

As was explained above, if the releasing apparatus should fail to operate, then a low 105 frequency sound signal is transmitted under water to the hydrophone 17 This causes the relay 55 to become energized which, in turn, effects the energization of the solenoid 57.

Accordingly, the solenoid 57 draws its 110 armature 58 into the position shown in Fig.

4 with the result that the plunger 18 is moved into its operated position and performs the functions described above.

After the cable 11 has been released, the 115 winch on board the ship is operated to pull up the rope 4 for the purpose of retrieving the lowering device The chain 8 and the sleeve 9 are considered to be expendable and remain on the ocean floor with the cable 11 120 As soon as the weight of the lowering device is supported by the rope 4, the hoop 12 and the arms 13 will return to their normal condition This permits the link 29 and the bellcrank 30 to resume their positions shown in 125 Fig 2 However, the roller 33 on the pawl 32 will temporarily remain in contact with the plunger 18.

During the hoisting process, the hydrostatic pressure surrounding the bellows 43 is 130 955,598 time during the underwater lowering process regardless of whether the bellows 43 has been compressed to perform its arming function.

It is to be understood that this invention has been described above with reference to 70 a specific underwater lowering device for the purpose of explaining the principles and features of operation of the invention It is to be further understood that this invention is not to be restricted to this particular em 75 bodiment as various modifications may be made without exceeding the scope of the invention For example, instead of using an implosive signaling device, such as the glass ball 51, an explosive charge could be em 80 ployed or the plunger 53 could be designed to release a buoyant device which would rise to the surface of the ocean Also, the arming equipment could utilize a temperature-sensitive device in place of the pressure-sensitive 85 instrumentality represented by the bellows 43.

In addition, the arming apparatus and the emergency equipment could be designed to use timing mechanisms or water-soluble materials for initiating their operation 90