The present invention is concerned with a self- releasing device, such as a hook or shackle.

Hooks and shackles are widely used in many applications for lifting, carrying, lowering or dragging loads. However, unhooking a load manually can involve a certain amount of danger to the worker actually releasing the load, or indeed to other workers in that area, since the hook could lift up during the unhooking process and, once released, could swing around dangerously. The observation of various safety procedures needed for manual release of a load can cause delay in the unhooking process .

The disadvantages of releasing loads from hooks manually has led to the development and use of self- releasing hooks, where the hook is designed to release the load automatically, as soon as the load has been deposited. For safety reasons, a self-releasing hook should be incapable of releasing its load prematurely.

One commercially available self-releasing hook is known as the Fleming hook. Here, the actual hook is located on the lower end of an upright which forms one side of a pivoted parallelogram arrangement. When loaded and under tension, the mouth of the hook is closed off by

the lower cross-piece of the parallelogram. Depositing the load releases the tension through the hook, allowing the parallelogram to pivot open, altering the angle of the cross-pieces so that the hook mouth is no longer closed. The Fleming hook suffers from the disadvantage of being extremely large and unwieldy. Moreover, the lever action of the cross-pieces allows release of the load to be triggered accidentally if the cross-pieces become at all snagged or caught.

Another self-releasing hook is described in GB-A- 2102488. The hook disclosed consists of two telescopically sliding members. The load-bearing element of the hook is part of the hollow outer member, thus reducing the strength and load-bearing capabilities of the hook. The load is prevented from falling off the load-bearing element by a locking piece attached to the inner member. The strain of the load is shared only between the load-bearing element and the locking piece.

The present invention provides a self-releasing device with a high strength to weight ratio, thus overcoming the problems encountered in the prior art.

In one aspect, the present invention provides a self- releasing device (such as a hook or shackle) comprising a body member and a locking member, the loaded device being adapted to remain in a load-securing first configuration when a tractive force is applied to said body member, and said device adopting a load-releasing second configuration when said tractive force is discontinued. Depending on the design of the device, the tractive force experienced by the body member of the loaded device may be communicated via the locking

member.

According to a further aspect of the present invention there is provided a self-releasing device (such as a hook or shackle) comprising a body member and a locking member, said body member being adapted to have a tractive force applied thereto for the lifting or pulling of the device and of any load attached thereto or secured thereby, said locking member being movable with respect to said body member between a first position providing a load-securing configuration of said device and a second position providing a load- releasing configuration of said device, said device being adapted to remain in said first configuration while a tractive force is applied to said body member and to cause or allow said locking member to move to said second position upon discontinuance of said tractive force whereby to bring about said load- releasing configuration.

In one embodiment, the present invention provides a self-releasing device (such as a hook or shackle) comprising a body member and a locking member slideably mounted therein, wherein one of said locking and said body members comprises a striker or other means to cause the device to adopt a load-releasing configuration and the other of said members comprises a loading link.

The term "striker" refers to any part or extension of a member which contacts the load or other surface (such as the ground) and causes the device to move relative to that member. Other ways of causing the device to adopt the load-releasing configuration include spring means coupling the body and locking members and which

bias the locking member towards the load-releasing second configuration. Premature release of the load does not occur when the biasing force of the spring means in less than the tractive force applied to the loaded device and/or if a catch or locking mechanism is present. Discontinuation of the tractive force allows the biasing force to urge the device into the load- releasing second configuration.

In a preferred embodiment, the locking member has a substantially "U"-shaped portion.

Generally, the load is attached to the device according to the invention by connectors such as straps, slings, ropes, loops, chains, wires or the like. Optionally, the load may also be connected via a conventional hook which engages with the self-releasing device of the invention.

The body member is adapted to receive the connector(s) and may be shaped accordingly. For example, the body member may possess a recess (the word "recess" being used herein to refer to any ledge, lip, cavity or the like) which receives the connector(s) . The load is secured on the device by the locking member which acts to prevent premature release of the connector(s) . Optionally the locking member may comprise a bolt or latch which substantially closes the part of the body member adapted to receive said connector(s) .

When the device is loaded, the tension acts to force the device into its closed position with the locking member preventing release of the connector(s) from the body member. Only when the tension in the device is released can the locking member or body member slide

relative to each other, opening the device. Preferably the locking member or body member may slide relative to each other in a substantially linear sliding movement.

Where the locking member has a substantially "U"-shaped portion, one arm of the "U" may act to secure the connector(s) in position by at least partially closing (preferably completely closing) the mouth of the recess in the body member or by protruding through the recess in the body member to prevent release of the connector(s) .

In one particularly convenient embodiment the locking member is adapted to urge the connecter(s) out of the recess of the body member, thus encouraging complete release of the device. Optionally this action occurs as the device moves into its second (open) configuration. As an example, the end of the non- locking arm in a locking member having a substantially U-shaped portion may be wedge shaped. In the first (loaded) configuration, the recess in which the connector(s) is located is backed by the thinner portion of the wedge and in the second (open) configuration the arm moves so that the thicker end of the wedge occupies at least part of the recess. Thus, the volume available to contain the connecter(s) is reduced, encouraging the connector(s) to become disassociated from the device.

Preferably the securing arm of the locking member engages with an indentation in the body member when in the locked position and completely closes the mouth of any recess in the body member. Where the locking member engages with the body member at each side of the recess the stress from the load is borne in part by the

body member in the closed device. Preferably, the securing arm of the locking member, when closed, is located in the body member at each side of the recess receiving the connector(s) .

Where one arm of the "U"-shaped portion of the locking member acts as a securing arm, the striker or loading link is conveniently attached to (or is attached to part of) the other arm of the "U"-shaped portion. Preferably, the striker or loading link is located at the end of that other arm. For ease of manufacture a loading link or striker may be welded to the arm of the "U"-shaped portion or may be attached by other convention methods, such as a screw engaging means (for example a screw thread co-operating with a corresponding thread on the arm of "U"-shaped portion), may also be used. Optionally, the end of the arm itself may be used as a striker.

The device according to the invention may be made with any suitable material. The choice of material will be determined by the envisaged function of the device and the amount of stress to be withstood. More usually the device will be made of ferrous or non-ferrous metals or metal alloy for example steels such as stainless steel, a low carbon content steel or other high grade steels such as EN12 steels. Brass may also be used, in particular for applications involving a highly corrosive environment. However the use of plastics may also be suitable in certain applications.

Preferably, the securing arm of the locking member is slideably mounted, preferably mounted in a bore, within the body member. Conveniently both arms of the "U" shaped portion are slideably mounted in the body member

and again, may be conveniently located in bores within the body member.

Optionally, the striker may be shaped as a loop or hook so that the load may also be attached to the self- releasing device in a second location. Attaching the load to the striker in this manner may be preferred since the stress of the load is then borne by the device as a whole and does not fall solely on the locking member.

For certain applications it may be convenient for the striker to be adapted to interface with the locking member so that movement of the striker causes the locking member to move in a substantially transverse direction thereto. For example, the striker may be positioned substantially vertically and the locking member positioned substantially at right angles thereto. The striker may be a pin, located in a bore within the body member and positioned so that as the pin strikes a surface the body member moves relative to the pin. Thus, the end of the pin internal to the body member engages with the locking member causing the locking member to move, releasing the connector(s) . The pin may cause transverse movement of the locking member by an convenient means, for example by a camming action. In one embodiment the internal end of the pin is wedge-shaped and in the first configuration is slideably abutted to a wedge-shaped portion of the locking member.

The striker of the device may include a pivoted section. The unloading of a device with a pivoted striker is enhanced by enabling the body of the device to fall during unloading. Optionally the pivoted

striker may only allow movement of the body in a restricted manner. Optionally the degree of restricted movement is determined by the position of stoppers. In this arrangement as the device is put down the main body of the device falls in one particular direction and this may be advantageous for reasons of safety and also to further aid the automatic unloading of the device.

The present invention also encompasses a multiple self- releasing device, that is to say the invention comprises a device having the ability to attach to more than one connector separately and in a self-releasing manner. The multiple device may have a single body member adapted to receive more than one connector in distinct locations or alternatively may have multiple body members each adapted to receive at least one connector. Optionally two or more body members may be joined together (optionally via a spacing structure) in the multiple device of the invention. Similarly there may be separate locking members to secure each connector to the multiple device, or a locking member may be adapted to secure more than one connector. The multiple self-releasing device described above may be used to attach several loads, but is also of application where a single load is secured with several connectors, two or more of which are then attached separately to the multiple device.

In one particularly useful embodiment, the self- releasing hook has the ability to attach two connectors separately. This includes the situation where the two connectors are separate or opposite ends of the same connecting means securing the load, for example are separate ends of a piece of rope, chain etc attaching

the load.

In a further embodiment the device according to the present invention may also comprise a safety catch. Optionally the safety catch prevents movement of the locking member when the device is loaded.

In one convenient embodiment, the device includes a locking member having a substantially "U"-shaped portion and a safety catch attached to the body member via a pivot. The safety catch includes a loading link on one side of the pivot and a locking end at the other side of the pivot. When the device is loaded, the safety catch is moved into a locking position with the locking face of the safety catch preventing relative movement of the locking member and body member. The safety catch adopts its locking position automatically as the tractive force is applied through the safety catch. Thus, when the device is in the first (loaded) configuration the locking member cannot be released, and only when the device is put down can the safety device rotate about the pivot and allow the locking end of the catch to move so that the locking member may release the connector(s) .

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows in perspective an embodiment of the invention in the closed position;

Figure 2 shows in perspective the embodiment of Figure 1 in the open position;

Figure 3 shows in perspective a further embodiment of the invention in the closed position;

Figure 4 shows in perspective an embodiment of a multiple self-releasing hook of the invention;

Figure 5 is an elevation of a fourth embodiment of the present invention;

Figure 6 is a section of the fourth embodiment, taken on the line VI - VI in Figure 5;

Figure 7 is a plan view of the fourth embodiment;

Figure 8 shows in perspective a shackle according to the invention; and

Figure 9A and 9B show details of a spring biased device with a catch arrangement to prevent premature release of the load.

Figures 10A and 10B show an embodiment of a device having a safety catch and also a pivoted striker.

Figure 11 shows a device according to the invention having a wedge-shaped portion of the locking member to encourage release of the connector(s) and a transversely positioned pin which acts as a striker.

Referring to Figures 1 and 2 the self-releasing hook comprises a body member (1) in which is slideably located the locking member (2) . Locking member (2) has a "U"-shaped portion with the two arms of the "U" being located in bores within body member (1). One arm of the locking member (2) is the securing arm (7) which

1 prevents release of the load prematurely. In the

2 closed position illustrated in Figure 1, securing arm

3 (7) is also located in corresponding indentation (8).

4 The other arm (9) terminates with a striker (5) which

5 may be welded thereto or secured by a screwing

6 mechanism. The self-releasing hook is suspended from

7 the loading link (3) and the load is suspended from a

8 connector which passes through the closed gap formed

9 between the recess (4) of body member (1) and securing

10 arm (7). The opposite end of the connector may be

11 attached to the eye (6) of striker (5) at the lower end

12 of arm (9). As shown in Figures 1 and 2, arm (7) of

13 locking member (2) may be shorter in length than arm

14 (9). 15

16 In order to open the hook without the necessity for

17 manual assistance, the hook and load are lowered until 18. the load comes to rest and its weight is taken off the

19 self-releasing hook. The hook is then further lowered

20 until the striker (5) which is attached to the longer

21 arm of the locking member (2) is contacted. The body

22 member (1) continues to fall relative to locking member

23 (2), thereby causing locking member (2) to rise

24 relative to the body member (1). Securing arm (7)

25 rises with locking member (2) opening the mouth of

26 recess (4). The connector suspending the load

27 previously secured between recess (4) and securing arm

28 (7) then falls clear of the self-releasing hook by

29 gravity and the hook assembly can be lifted clear by

30 means of suspension attached to the loading link (3).

31 The opposite end of the connector suspending the load

32 remains attached to the self-releasing hook at eye (6).

33 The self-releasing hook can now be lifted clear of the

34 load and can be re-positioned for its next lift. 35

Figure 3 illustrates a further embodiment of the invention. Here, striker (5) is attached to body member (1) whilst loading link 3 is attached to arm (9) of "U"-shaped locking member (2). Securing arm (7) of locking member (2) is again located within a bore in body member (1) and when the hook is suspended, securing arm (7) is also located in indentation (8) in body member (1), thus closing the gap between recess (4) and securing arm (7) . In contrast to the embodiment of Figures 1 and 2, arm (9) is attached to body member (1) by securing band (10a), (10b) and (10c).

When striker (5) is contacted during the lowering process, continued lowering causes locking member (2) to slide relative to body member (1). Securing arm (7) drops down with further lowering, releasing the connector and thus the load. Optionally the other end of the connector may also be attached at eye (6) of striker (5) .

Figure 4 shows a multiple self-releasing hook. In this embodiment body member (1) has two recesses (4) and (4') closed off by securing arms (7) and (7') respectively, which in their closed positions reside in indentations (8) and (8').

In the embodiment illustrated, securing arms (7) and (7') are part of a single locking member (2) which can be considered to have two "U"-shaped portions. A central arm (9) is located in a bore within body member (1) and terminates in striker (5) which possesses an eye (6) to which the load may also be attached. The hook of Figure 4 (shown in its closed position) may be suspended by means of loading links (3) and (3').

Lowering the loaded hook results in striker (5) being contacted by the load or ground once the load has been deposited. Body member (1) is further lowered relative to locking member (2) thus opening recesses (4) and (4') and releasing the connectors and thus the load.

Referring now to Figures 5-7, these illustrate a fourth embodiment of the present invention, in the form of a self-releasing hook (100) (which may also function as a self-releasing shackle, as will be apparent from the following description). The hook (100) comprises a body member in a generally "U"-shaped form (102) having a base (104) and free ends (106), (108).

A mutually co-axial pair of holes (110), (112) are formed in the free ends (106) and (108) respectively, to allow the insertion of a pin (not shown) for the attachment of a lifting cable (not shown) or a tow rope (not shown) to the hook (100).

The hook body (102) has a further pair of holes (114), (116) formed in the body base (104), the further holes (114), (116) being aligned mutually parallel and generally towards the free ends (106), (108).

The hook of 100 further comprises a second member in the form of a "IP-shaped rod-section bolt (120) dimensioned to be a sliding fit in the further holes (114), (116). The bolt (120) has a short leg (122) which fits within the hole (114), and a long leg (124) which passes through the hole (116) to extend below the body base (104) where it is fitted with a collar (126) retained by a screwed-on eye fitting (128).

A side opening (130) in the body base (104) extends

laterally about halfway across the base (104) to form a throat (132) laterally inwards of the intersection of the opening (130) with the hole (114).

Figures 5 and 6 show the bolt (120) in a first position with respect to the body (102), in which the bolt (120) extends downwards as far as possible, ie until the junction of the bolt legs (122), (124) impinges upon the saddle of the body (102) where the free ends (106), (108) are mutually joined by the base (104). In this first position of the bolt (120), the bolt by (122) closes the throat (132) such that any cable, chain link, sling or other load attaching connector (not shown), looped through the throat (132) is prevented from escaping therefrom.

The bolt (120) is capable of moving to a second position (not shown) with respect to the body (102), by upward linear sliding movement of the bolt (102) in general, and of the bolt legs (122) and (124) within the holes (114) and (116) in particular, to a limiting position in which the collar (126) abuts the underside of the body base (104). In this second (upper) position of the bolt (120) with respect to the body (102), the short leg (122) of the bolt (120) clears the side opening (130) such as to open the throat (132) to the release therefrom of any cable or other load- attaching connector previously retained by the bolt (120) being in its first (lower) position with respect to the body (102) .

Movement of the bolt (120) from its first (lower) position with respect to the hook body (102) to its second (upper) position with respect of the hook body (102) can be induced by lowering the hook (100) on the

end of a lifting cable attached by a pin passing through the holes (110), (112) until a load (not shown) carried by the hook (100) touches the ground or other load-receiving location to relieve the tension in the lifting cable, followed by further lowering of the hook (100) until the eye fitting (128) and/or the collar (126) rest on the upper surface of the load, where upon a slight further lowering of the hook (100) causes the hook body (102) to slide downwards relative to the bolt (120), this being mechanically equivalent to moving the bolt (120) from its first to its second position relative to the hook body (102) and releasing the cable or other load-attaching means from the throat (132). Assuming another part (eg the other end) of the cable or other load-attaching means to have been attached to the eye fitting (128), the cable will now be pulled free of the load by raising of the hook (100), leaving the load where it was deposited and now fully detached from the hook (100) without any direct intervention by an operator.

One or more springs (not shown in Figures 5 and 7) may be incorporated into the hook (100) to act in and between the hook body (102) and the bolt (120) such as to bias the bolt (120) from its first (lower) position with respect to the hook body (102) (as shown in Figures 5 and 6) to its second (upper) position with respect to the hook body (102). Spring-induced movement of the bolt (120) from its first to its second position is expected to be of particular use where the hook (100) is utilised to shackle a dragline (not shown) to a sling (not shown) encompassing a log (or other drag load) for the towing of the log, it being intended that the dragline be released from the log at the end of towing without on-the-spot intervention by

an operator. To prevent premature release during towing or lifting, but to ensure reliable release upon cessation of towing or lifting, the spring bias should be substantially less than the normal towing or lifting force applied through the hook or shackle (100) but sufficiently greater than the friction and any other forces inhibiting release upon cessation of towing or lifting as to ensure reliable movement of the bolt ( 120) from its first position with respect to the body (102) to its second position with respect to the body.

Figure 8 illustrates a shackle according to the invention. In this Figure, the body member 1 includes a mounting for a roller (11). Roller (11) can rotate in either direction as directed by the arrow. The locking member (2) is again "U"-shaped with the locking arm (7) closing off the recess (4) of body member (1). The other arm (9) of locking member (2) is located within a bore of the body member (1). The locking member (2) is biased toward a load-releasing position by a spring means located within the bore holding arm (9) of locking member (2) and/or a spring means located at the apex of the of the "U" portion of locking member (2) (not shown). Premature release of the load may be prevented by a lock or catch which counteracts the biasing of the spring means whilst the shackle is under tension.

The load connector may be held by locking arm (2), pass around the load and around roller 11 to the lifting or pulling apparatus. The presence of the roller helps to keep the connector, which is usually a chain, free running.

The shackle illustrated in Figure 8 is especially

suitable for dragging or pulling applications.

Figure 9 shows details of a device according to the invention with biasing means to urge the device into a load-releasing configuration. The device illustrated also includes a catch arrangement to prevent premature release of the load. The catch arrangement may be located at other convenient locations within the hook.

Figure 9A shows the device in a closed, but pre- tensioned state. The spring biasing means (12) is compressed, but is prevented from releasing the locking arm due to the engagement of protuberance (13) with the corresponding recess (14) in locking arm (7). The diameter of bore (8) is wider than the cross-sectional diameter of locking arm (7) so that when the device is tensioned by applying a tractile force thereto, the locking arm (7) moves within bore (8) to disengage recess (14) from protuberance (13), adopting the configuration shown in Figure 9B.

The spring biasing means (12) is unable to cause locking member (2) to move relative to body member (1) whilst the device remains subjected to the tractile force. Once the tractile force is reduced or removed, the spring biasing means (12) urges locking member (2) upwards, opening the device and releasing any connector held in the gap between recess (4) and locking arm (7).

Referring to Figures 10A and 10B the self-releasing device comprises a body member (1) in which is slideably located the locking member (2). Locking member (2) has a "U"-shaped portion with the two arms of the "U" being located in bores within body member (!)• The device operates essentially as described for

the embodiment illustrated in Figure 1. In Figure 10A the "U" portion of locking member (2) abuts a curved face (15) of safety catch (16). Locking member (2) is unable to move relative to body member ( 1) due to the position taken up by safety catch (16). Safety catch (16) is pivotably mounted in body member (1) via pivot (17) and includes a loading link (3). In the embodiment illustrated, the device is shown in the first configuration, with the loading force applied via safety catch (16). Safety catch (16) is prevented from rotating completely about the pivot (17) by stopper (18), here shown as a ledge within body member (1).

In order for the device to release the load, safety catch (16) must first rotate around pivot (17) in the direction of arrow A as shown in Figure 10B. Rotation occurs when striker (5) contacts the surface on which the load is to be released, or the uppermost portion of the load placed on that surface. The tractive force in safety catch (16) is thus released enabling rotation in the direction of arrow A. Optionally the safety catch may be biased towards rotation, for example by insertion of a spring in stopper (18).

The curved face (15) of safety catch (16) is thus rotated away from the "U" portion of locking member (2). Body member (1) is then able to move relative to locking member (2) and the securing arm (7) of locking member (2) rises, opening the mouth of recess (4). The connector (not shown) attached to the load may then fall free of the device.

A pivoted striker (5) is also present in the embodiment shown in Figures 10A and 10B. The pivot (19) ensures that body member (1) must fall in the direction of

arrow B. Optionally this is achieved by the use of stoppers (20). A pivoted striker allowing the device to be put down in a particular direction is advantageous for safety reasons. It is preferred that the device pivots around striker (5) so that the mouth holding the load connector(s) faces downwards; this assists in achieving unloading without any manual interference since the momentum from the body of the device falling downwards helps to expel the load connector(s) from their position.

In the embodiment shown in Figures 10A and 10B the two pivots (17) and (19) permit rotation in opposite directions. This arrangement is advantageous since the device essentially folds up on itself during unloading and reduces the space required for the unloading operation.

Figure 11 shows a further embodiment of the present invention. A locking member (2) having a substantially "U"-shaped portion is located within body member (1). The non-securing arm (9) of locking member (2) terminates in a wedge-shaped portion (21). This wedge- shaped portion (21) has two angular faces (22) and (24). The device will be loaded via loading link (3).

Face (22) of wedge-shaped portion (21) abuts a co- operating face (23) of pin (25) which acts as a striker. When pin (25) contacts a surface, body member (1) moves relative to pin (25) in the direction of arrow C. The interface between face (23) of the pin (25) and face (22) of locking member (2) causes movement of locking member (2) in the direction of arrow D, relative to body member (1). Securing arm (7) rises with locking member (2) opening the mouth of

recess (4). The load connector (not shown), previously secured between securing arm (7) and recess (4) may then fall free of the device.

In place of abutting faces (22) and (23), it is possible to use any mechanism capable of converting movement in one direction to movement in a substantially transverse direction, for example a camming action.

The embodiment illustrated may be particularly useful for applications where the device is to be used at an angle to the vertical, for example in lifting sections of piping where one device is secured at each end of the pipe, but both are ultimately lifted by a single crane.

When locking member (2) moves in the direction of arrow D during the unloading operation, face (4) moves into recess (4) and fills the innermost portion of recess (4). Thus, as locking member (2) rises to open the mouth of recess (4) enabling release of the connector(s) the volume of recess (4) available to hold the connector(s) is reduced and thus the connector(s) previously secured by the device are urged out of recess (4) and unloading is facilitated.