GB2191750A - Sling grip - Google Patents

Abstract

A sling grip for a loop of chain or the like comprising first and second components (1,2) capable of relative sliding movement in opposite directions, an anchorage for one end of the loop mounted the first component, and a rotatable profiled wheel (11) also so mounted, the other end of the loop engaging with the wheel. At one extreme of the relative movement of the two components eg farthest apart, the wheel is free to rotate and so release the chain, while at the other extreme, closest together, the wheel and chain are both engaged by a recess 16 on the second component (2) and the chain loop is therefore secured. When a load contained within a secured loop of chain is lowered onto the ground, the two components slide to the relative position in which the wheel becomes disengaged, thus releasing the loop so that the load may be released from it. Catch means are described for insuring that once the wheel is so released, it does not become engaged again - for instance, if the grip is hauled up by a crane - unless the catch means have first been reset. <IMAGE>

Description

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GB2 191 750 A

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SPECIFICATION

Improvements in or relating to sling grips

5 This invention relates to devices whereby a flexible and elongated member of profiled surface, such as a chain, capable of making positive engagement with a profiled wheel such as a sprocket, can be formed into a loop or sling of variable length and secured in 10 thatformation, wherebya load encompassed bythe loop may safely be raised or lowered by raising or lowering the device itself. Such a device will be referred to as a sling grip, and theflexible elongated member of which the loop is formed will be referred 15 to asthe sling material.

In particularthe invention relates to sling grips adapted to be suspended either directly or indirectly from the hook of a crane, and to be used to encompass loads that need to be transported bythe 20 crane and require to be automatically detached from the grip aftertransportation. Astructural beam is such a typical load: because of its length, it requires two slings, one at each end, and the slings can be attached to opposite ends of a lifting beam, the beam 25 being attached to the crane hook. Fitting of such loads with slings before transportation normally presents few problems to trained personnel, but the separation by hand of a sling from its load afterthe latter has been transported, especially when it is then 30 fixed into an elevated position e.g. into a structural framework, is notoriously hazardous. To reach the slings in orderto releasethem, an operator may have to climb out onto the load itself, which may be slippery and/or present only a limited foothold, so 35 that he is in danger of falling off.

Sling grips have been proposed including release mechanisms capable of being operated by remote control,for instance by radio signal, or electrically, or mechanically by a Bowden cable or the like. 40 However, reliable radio control can be difficult to achieve in the typical hostile environment where such sling grips are used, and the electrical and mechanical alternatives just mentioned involvethe extra hazard of trailing leads or cables between the 45 sling grip and the operator. Also, in the absence of elaborate safety devices and precautions, such mechanisms have the inherent danger that they can be operated inadvertently and disastrously while a load is still in transit.

50 An object of the present invention is to provide a simple sling grip, which can be caused to open when required without the need for remote operator control of the kind just described, yet which ensures to a high degree of reliability that a load cannot be 55 liftedandtransportedunlessthesling isfirmly secured by the grip. According to the invention a sling grip comprises a first component adapted for connection to lifting gear, and in engagement with a second component including means to promote a 60 stable landing when it is lowered onto a surface, the firstand second components being capable of relative sliding movement in opposite directions; an anchorage, formed on one of those components, for one end of a loop of sling material; a profiled wheel 65 mounted on one of those components, for engagement with the other end of the loop; and detent means operable both to prevent rotation of the wheel and also to mask it, that is to say to prevent the sling material escaping radially-outwardsfrom it, 70 wherebyfull relative movement of the two components in one direction facilitates free rotation of the wheel and the paying out of the sling material, whereasfull relative movement in the other direction engages the wheel and detent means and so secures 75 the second end of the loop to the device. Movement of the two components of the sling grip in such a way that the profiled wheel and detent means separate will be referred to as "apart"; movement in such a way that the wheel and detent means engage with 80 each other will be referred to as "together". The wheel may be mounted on the first component and the detent means on the second component, the detent means may engage with a member of symmetrical butnon-circularform 85 attached to and coaxial with the wheel, and the detent means may include a complementary recess to engage with that member when the two components slide together. The detent means may be fast with the second component. 90 Alternatively the wheel may be mounted on the first component and the detent means may include a pivotted arm, also mounted on thefirst component and capable of pivotting to a position in which it locks the wheel. The detent means may also 95 comprise a connection between the second component and the arm, operable to move the arm respectively towards and away from the locking position as the two components slide respectively together and apart. The connection may be of 100 pin-and-slottype, with the slot formed in the second component, and the pin mounted on the lever. The arm may carry a tooth or other projection adapted, when the arm is in its locking position, to make positive engagement with the chain or other sling 105 material passing overthe pulley. Another projection, carried by the second component, may also be adapted to make positive engagement with the wheel and so constitute further means to prevent it from rotating.

110 A stop may be provided that is operable, as the first and second components slide apart awayfrom their fully-together position, to take up a first position in which it prevents the two components from sliding fully together again andthus leaves the 115 wheel free to rotate. There may also be retaining means to hold the stop in an opposite, second position to which it can be returned, and in which it permits the two components to approach their fully-together position again, and there may be 120 means, as the first and second components approach theirfully-together position, to disengage the retaining means so that the stop is free to move to its first position once the two components move apart again.

125 The invention will now be described byway of example, with reference to the accompanying drawings in which:-

Figure 1 is a perspective view of one sling grip, in thefully open position and from the front; 130 Figure 2 is a perspective view of part of the same

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sling grip, half closed and from the rear;

Figure 2a shows a detail of Figure 2 in alternative positions;

Figure 3 is a perspective view of a second sling 5 grip, in the open position and from the front, and

Figure 4\s a simplified section, taken on the line IV-IV, through parts of the grip of Figure 3.

The sling grip of Figures 1 and 2 comprises first and second components indicated generally at 1 and 10 2. Atthe top of component 1 is an aperture 3to receive the pin of a shackle by which the grip may be suspended from the hook of a crane orfrom a lifting beam. Belowthe aperture 3 thefirst component presents a stop 4, and belowthat a 15 rectangular-section spine 5, the base of which is integral with one end of a cross member 6, the other end of which is integral with the base of an upstanding flange 7. A carrying handle 8 is mounted on a boss 9 atthe upper end of flange 7, and the 20 flange and spine between them support an axle 10 supporting a profiled wheel 11. Side walls 12 attached to the wheel have the shape of regular pentagons, the centre of each of which coincides with the wheel axis.

25 The topmost element of the second component 2 is a massive block 15 the lower face of which is formed with a recess 16of part-pentagonal shape complementary to that of the walls 12. Block 15 is securely bolted to flanges 17 themselves fixed to the 30 upper end of a spine 18, the lower end of which is turned into one end of a cross member 19. The other end of member 19 is turned into a short upright flange 20. As Figure 1 shows, cross member 19 is longerthan cross member 6, so that spine 18 lies 35 behind spine 5 and flange 20 lies in front of flange7. Beneath the member 19, and attached to it by a nut 23, is mounted an open-work structure 24, roughly of saucer-shape, the purpose of which is to promote a stable landing of the sling grip when it lands under 40 gravity on an upward facing surface, so that ittends notto topple overbutto rest with spines 5,18 reasonably upright.

Spine 5fits with sliding clearance within an aperture 26 defined by spine 18 and a cutaway in the 45 rearface of block 15. Components! and 2 are therefore free to si ide relative to each other i n opposite directions, which will be referred to as together and apart. In Figure 1 the two components are shown atthe extremity of their movement apart, 50 in which the top face of block 15 abuts the stop 4. At the other, fully-together extremity of their relative movement, it will be apparentthatthe wheel 11 will have entered the recess 16, and that reaction between the recess walls and the side walls 12 will 55 have imparted the slight rotation (ifany)tothewheel that is necessary forthe pentagonal sides 12to registerfully with the complementary shape of recess 16, so that wheel 11 is locked against rotating.

The material of which the sling loop is to be 60 formed, and which is to be gripped by the sling grip just described, is a chain 30, one end of which is fixed to an anchorage (where indicated generally by 31) on the side of block 15 which, as already explained, is part of the second component 2. Thatanchorage 65 forms one end of thesling loop. The other end of the loop is in effect the location where chain 30 contacts wheel 11. That wheel, while free to rotate on axle 10, is of chain-pulley form including teeth 33 which engage positively with the chain. When the walls 12 70 are in full engagement with the recess 16 the wheel is prevented from rotating and therefore the chain 30 is prevented from paying in orout: also, the closeness of the wheel to the block 15 is such that the block effectively "masks" the wheel, preventing the chain 75 from escaping radially-outwardly from it. Both ends of the loop of chain are therefore securely held, so that a secure sling of fixed length is defined and ready for use.

Atypical sequence of operation of a sling grip as 80 shown in Figures 1 and 2 will now be described, beginning with components 1 and 2 fully apart as shown in Figure 1. Component 1 will be attached to the hookof a crane (not shown) which will manoeuvre to locate the grip above the load which is 85 to be lifted, and then to lower it until structure 24 rests on top of the load, with the crane line just taut.

The operator now passes the chain 30 down and underneath the load, making a first limb of the sling, and then in a second limb up and overthe wheel 11 90 so that the loop is completed, ensuring thattheteeth 33 engage cleanly with the links of the chain. He will now pull on thefree end 35 of the chain until the loop is without undue slack. The free length of chain hanging toone side ofthe wheel 11 should now be 95 longer- and therefore heavier-than the limb ofthe sling loop lying to the other side, thus avoiding the possibility that the chain will run backwards off the pulley when the operator lets go of thefree end 35. When the crane driver now hauls in his line gently, 100 structure 24 and the rest of component 2 will remain seated on top ofthe load, due not only to gravity but also to being held down bythe tautening first limb of thesling loop. The components 1,2 will however move together because the first component 1 will 105 rise, so that spine 5 slides upwards within aperture 26. Any rotation of wheel 11 asthishappenswill cease as soon as the shaped sides 12 of the wheel enter and register with the recess 16. The crane driver continues to gently take in his line until the 110 sling loop becomes quite taut, and then the load is lifted. While the load is in the air, the opposed forces ofthe crane line upon component 1 and the weight of the load upon component 2 prevent disengagement of wheel 11 from recess 16, and therefore ensure that 115 thesling loop remains securely fastened.

Once the load has been transported, positioned and secured, the first consequence as the line is payed out is that the two limbs ofthe sling loop both slacken progressively, but the wheel 11 and recess 120 16 remain in engagement because the component 1 is supported from the crane li ne whereas the force of gravity acts upon component 2. As the crane continues to pay out, downward motion of component 2 ceases when structure 24 comes to rest 125 on the load, the shape ofthe structure being such as to promote a stable landing in which spine 18 remains reasonably upright. As the crane pays out still further, components 1 and 2 move apart because component 1 continues to descend so that wheel 11 130 fallsoutofengagementwithrecess16.

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An operator could then undo the sling by simply removing chain 30 from wheel 11, and pulling the free end 35 out from under the load in the reverse of the operation by which he previously formed the 5 sling. Howeverthis operation can be dangerousfor reasons already described. Figures 2 and 2a showa mechanism whereby such danger is avoided by effecting disengagement ofthe chain from the load in a manner requiring no participation bythe 10 operator. A latch 37 is pivotted to the rear face of block 15 about an axis defined by a bolt 38, which engages with a tapped hole (not shown) in the biock 15. A magnetic catch 39, fixed to one of theflanges 17, is located so as to receive and hold the latch 37 in 15 the position in which it is shown in Figure 2, and which is the anti-clockwise extreme (as shown in that Figure) of its pivotal movement. A second bolt 40, which like bolt 38 projects from the back of block 15, provides a stop to hold latch 37 atthe opposite 20 (clockwise as in Figure 2) extreme of its pivotal movement: this extreme is shown in broken lines at 37a in Figure 2a, and the end ofthe latch also appears at this position in Figure 1. Afinger 41 (omitted from Figure 1) is mounted on the rear face of spine 5 which 25 also carries a boss 42 complementary to boss 9. A lug 43 projects from boss 42.

When an operator engages chain 30 with wheel 11 to form a sling loop, as already described with reference to Figure 1, he ensures that latch 37 is held 30 by catch 39, as shown in Figure 2. As the crane driver then starts to haul in his line, so that component 1 rises while component 2 remains resting on the load, just before these two components reach full engagementthefinger41 contacts the latch 37 and 35 pivots it slightly clockwise so that it loses contact with catch 39, which exerts only a slight magnetic force. This leaves the latch in the position indicated in broken lines at 37b in Figure 2a. As components 1 and 2 now proceed into theirfully-together position, 40 which they retain throughoutthe ensuing lift ofthe load, the latch remains in position 37b and is prevented from further clockwise pivotting bythe engagement of its heel 44 with boss 42. However when the load is put down again, the component 1 45 descends relative to component 2 in the manner already described, first boss 42 and then lug 43fall out of register with heel 44 so that latch 37 is free to pivot to position 37a. Wheel 11 will also have fallen out of register with recess 16, and if the crane driver 50 now hauls on his line so as to raise component 1, before the wheel and recess comes into register again the upper end of lug 43 will come up against latch 37 at about location 45 (Figure 2a) and so prevent components 1 and 2from moving further 55 together. As the crane line continues to haul, it will therefore lift both components together clear ofthe load, so that the chain tautens and the free end 35 automatically unwinds over wheel 11 andfallsfree. Continued hauling-in bythe crane driver would 60 remove the device and sling away from the load. To put the device in a condition in which it is ready for its next load, the operator must then flick latch 37 back into engagement with catch 39 in the manner already described.

65 In the second version ofthe invention shown in

Figures 3 and 4, components 50 and 51 are analagousto items 1 and 2 ofthe previousfigures. Component 50 presents an orifice 3 (containing a shackle 52, Figure 3) and supports a profiled wheel 70 53, and the openwork structure 24 (not shown in Figure 4) is attached to component 51. The mutual sliding of components 50 and 51 is guided by a slot 54formed within component 50 and the shaft 55 of wheel 53 which passes through the slot and is 75 supported at one end by the component 50 and atthe other end by a forward flange 62, itself secured to component 50 by spacer blocks 74. An arm 56 is pivotted about an axle 57 mounted on component 50, carries a pin 58 engaging with a slot 59formed in 80 component 51, is formed with an arcuate edge at 60 and presents a projection 61. Aspring-loaded pin 70 is mounted within a housing 71 fixed to component 50, and a hole 72 is formed in component 51. When components 50 and 51 are in the relative position in 85 which they are shown in Figures 3 and 4-that is to say, when they have moved "fully apart" as previously described - the tip 73 of pin 70 enters hole 72 underthe influence ofthe spring, so locking the two components in that relative position.

90 With components 50 and 51 fully apart as shown, the sling grip of Figures 3 and 4 is ready for use. Typically an operator first rests the structure 24 on top ofthe load to be lifted, so that the device stands as upright as possible. Then he passes the chain 30 95 so that it hangs downwardly from anchorage 31, passes underneath the load, then up and again over wheel 53 so as to form a sling loop. Then with one hand he will withdraw pin 70 out of engagementwith hole 72, while with the other hand he presses down 100 on arm 56, giving it a slight movement clockwise as shown in Figure3.Throughtheengagementof pin 58 with slot 59, this causes components 50 and 51 to move slightly "together" so that pin 70 and hole 72 are no longer in register. If nowthe crane raises 105 component 50 (by way of shackle 52) while component 51 remains at rest on top ofthe load, the relative movement ofthe two components continues until they are "fully together" when arm 56 has moved fully clockwise so that arcuate edge 60 comes 110 closetothematching upperrim75offlange62,so "masking" the wheel and preventing the chain 30 from escaping from it in a radial direction. Also,the projection 61 engages positively with the chain preventing it from paying in oroutcircumferentially, 115 andtherebysecuringthesling.Asameansof ensuring accurate engagement ofthe projection 61 into the chain, the rearface 63 ofthe wheel 53 may be formed with radiating vanes 64 (of which two are shown in Figure 4) which engage with a stop 65 on 120 component 51 when the two components move into theirfully-together position, as they are of course when a lift is in progress. When the lift ends andthe load is secured in the position to which it has been transported, the structure 24 alights on the secured 125 load, and the crane line continues to pay out so that component 50 continues to descend while 51 is stationary. The interaction of pin 59 and slot 58 now pivots arm 56 back to the position in which it is shown in Figure 3, and raises stop 65 clear of vanes 130 64, backtothe position in which it is shown in Figure

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4, and pin 70 re-engages with hole 72 so locking components 50,51 in their "fully-apart" position. The crane line can then be raised so thatthe chain 30 tautens and thefree end 35 automatically unwinds 5 overthewheel53andfallsfree.

Claims (1)

1. Asling gripcomprising:-

10 a first component adapted for connection to lifting gear, and in engagement with a second component including means to promote a stable landing when it is lowered onto a surface, the first and second components being capable of relative sliding 15 movement in opposite directions;

an anchorage, formed on one of those components,foroneendof a loop of sling material;

a profiled wheel, mounted on one of those components, for engagement with the otherend of 20 the loop; and detent means operable both to prevent rotation of the wheel, and also to mask it, that is to say to preventthesling escaping radially-outwardsfrom it, whereby full relative movement of thetwo 25 components in a first sense facilitates free rotation of the wheel andthe paying-out ofthe sling material, whereas full relative movement in the opposite and second sense engages the wheel and detent means and so secures the second end ofthe loop to the 30 device.

2. Asling grip according to Claim 1 inwhichthe wheel is mounted on thefirst component and the detent means on the second component.

3. Asling grip according to Claim 2 in which the 35 detent means is arranged to engage with a member of symmetrical but non-circular form attached to and coaxial with the wheel, and the detent means includes a complementary recess to engage with that member as the two components slide relative to 40 each other in the second sense.

4. Asling grip according to Claim 3 in which the detent means isfast with the second component.

5. AslinggripaccordingtoClaiml inwhichthe wheel is mounted onthefirstcomponentandthe

45 detent means includes a pivotted arm, also mounted on thefirst component and capable of pivotting to a position in which it locks the wheel.

6. Asling grip according to Claim 5 in which the detent means also comprises a connection between

50 the second component and the arm, operable to move the arm respectively towards and away from the locking position as the two components execute relative sliding in the second and first senses respectively.

55 7. Asling grip according to Claim 6 in which the connection is of pin-and-siottype.

8. Asling grip according to Claim 7 in which the slot is formed in the second component, and the pin is mounted on the lever. 60 9. AslinggripaccordingtoClaim5inwhichthe arm carries a tooth or other projection adapted, when the arm is in its locking position, to make positive engagement with the chain or other sling material passing overthe pulley.

65 10. Asling gripaccording to Claim 2 including a stop operable, as the first and second components slide relatively in thefirst sense, to take up afirst position in which it prevents the two components from reaching the extremity of their relative

70 movement in the second sense and thus ensures that the wheel remains free to rotate.

11. Asling grip according to Claim 10 in which there are retaining means to hold the stop in an opposite, second position to which it can be

75 returned, and in which it permits the two components to reach the extremity of their relative movement in the second sense.

12. A sling grip according to Claim 11 inwhich there are means, as the first and second components

80 approach the said extremity of their relative movement in the second sense, to disengage the retaining means so that the stop is free to move to its first position once thetwo components move relatively in thefirst sense once more.

85

Amendments to the claims have been filed, and have thefollowing effect:-

(a) Claims 7,8 above have been deleted ortextually amended.

90 (b) New ortextually amended claims have been filed asfollows:-

7. Asling grip according to Claim 6 in which the connection is between a pin and an orifice.

95 8. AslinggripaccordingtoClaim7inwhichthe orifice isformed in the second component, and the pin is mounted on the arm.

13. AslinggripaccordingtoClaiml, substantially as described with reference to the

100 accompanying drawings.

Printed for Her Majesty's Stationery Office by

Croydon Printing Company (UK) Ltd, 11/87, D8991685.

Published by The Patent Office, 25 Southampton Buildings, London, WC2A1 AY,

from which copies may be obtained.