US2410378A - Grip for hoists - Google Patents

Description

O. H. GALLAMORE lOct. 29, 1946.

GRIP FOR HOISTS Filed Jan. l, 1944 3 Sheets-Sheet 2 INVENTOR. @UVE/9j( f' OC. 29, 1946. o, H GALLAMRE 2,410,378

GRIP FOR HOISTS Filed Jan. l, 1944 3 Sheets-Sheet 5 K INVENTOR.

Patented Oct. 29, 1946 UNITED STATES TENT OFFICE Indiana Diamond Chain and Manufacturing Company, Indianapolis, Ind.,

a corporation of Application January 1, 1944, Serial No. 516,625

3 Claims. l

My invention relates to a sling adapted to grip cylindrical and similar objects and connectible to a hoisting cable or cables by means of which the object gripped can be elevated. It is the object of my invention to produce a sling which can be used to grip objects of varying diameters, and more particularly to produce a sling which will tighten itself upon the object as a result of the hoisting effort. Another object of my invention is to produce a sling which will not foul the hoisting cable or cables and which when released will quickly clear the object it previously gripped. Still another object of my invention is to produce a, sling which, when used to embrace an elongated object at or near its point of balance, will oppose any tipping of such object and will be especially effective to prevent the object from slipping through the sling. A further object of my invention is to produce a sling of the type described which can be simply and economically manufactured.

In carrying out my objects, I employ a exible chain connected to a hooked lever which is in turn connected to a hoisting cable. In the preferred arrangement, the chain comprises a series of links interconnected by transverse pivot pins the axes of which are all parallel to `each other, whereby iiexing of the chain will be confined to the single plane perpendicular to the pin-axes. The body of the chain passes around the object to be raised by the hoisting cable and is engaged by the hook of the lever, the hook and the points of attachment of the lever to the chain-end and the hoisting cable being so disposed that the forces involved will tend to tighten the chain upon the object it embraces when tension is applied to the hoisting cable. When the sling is used with a two-cable hoist, the hooked lever secured to one of the cables is disposed at one side of the object to be elevated, the chain passes downwardly beneath such object and then over it to be engaged by the hook on the lever, and the second cable is provided with a hook which engages the chain on the opposite side of theobject from the hooked lever. When the hook of the lever is disengaged from the chain after the object has been elevated, the free end of the chain passes over the top of the object, the weight of the chain is distributed between the two cables, and the latter may be permitted to descend under the influence of gravity.

The accompanying drawings illustrate my invention: Fig. 1 is an end elevation of an object embraced by my sling, the sling being shown as attached to two hoisting cables, and parts of the sling being broken away to illustrate the construction more clearly; Fig. 2 is an elevation on an enlarged'scale showing a hook employed to connect one of the hoisting cables to an intermediate point on the sling; Figs. 3 and 4 are plan and elevational views respectively showing the sling-tightening lever; Figs. 5 and 6 are frag-- mental views similar to Fig. 1 illustrating modied forms Yof sling-tightening levers; Fig. 7 is a fragmental View similar to Fig. 1 illustrating an attachment which may be employed in co-operation with the sling when the object has a shape such as might tend to prevent application of the sling at the point of balance; Fig. 8 is a vertical section on the line 3-8 of Fig. 7;`Figs. 9 to 12 are views similar to Figs. l and 5 showing slings used with single-cable hoists; 'and Fig. 13 is a view similar to Fig. 4 showing the sling-tightening lever of that gure used with a sling comprising tvvo` independent chain-strands.

The object which my sling is to grip is indicated by the reference numeral I0 in all figures of the drawings. The chain Il of which the body of the sling is formed may take various forms. That shown inthe drawings, which is of a preferred type, is made up of alternating bushing links and pin links, each bushing link comprising a pair of bushings l 2 pressed into holes in the ends of side plates i3, and each pin link comprising pins I4 pressed into holes in the ends of side plates I5. As is shown in Figs. 2, 3, and 4, the chain Il is a unitary, double-strand chain, the pins Ul being long enough to extend through' longitudinally coextensive bushing links of the two strands. It is not essential, however, that the chain be a doublestrand chain, nor is it essential that two chainstrands, if used, be combined into a single chain.

In the arrangement illustrated in Figs. 1 to 4 inclusive, one end of the chain l I is connected to an intermediate point on a sling-tightening lever I'l so arranged that when the sling is tightened it rwill extend generally radially of the object which the sling grips. The inner end of the lever Il is formed to provide for each strandv of the sling a downwardly opening hook I8, while the outer end of the lever is adapted for connection to, ahoisting cable I9. Conveniently, the outer lend' of vtheV lever Il is'bifurcated and receives Aa pin or bolt y2l) which passes through a thimble 2| about which the end of the cable I9 is secured, as will be clear from Figs. l and 3.

As previously indicated, the sling shown in Fig. l is adapted for use in connection with a twocable hoist. One cable oi such hoist is the cable i9, already referred to. The other cable,'indi 3 cated at 23 in Fig, 1, has its end secured around a thimble 24, such thimble being received between the ends of a U-shaped strap 25 and held in place by a pin or bolt 26. The strap 25, before being bent into its U-shaped form is provided with a longitudinally extending slotl 28 for each strand of the chain II; and after the strap is bent each of the slots 28 receives a hook 29. Where a multi-strand, unitary chain is used, or where a plurality of independent strands form the sling, the several hooks 29 are desirably secured together in spaced relation by a rivet 39 and are jointly held in place in the strap 25 by means of a common pivot pin 3|. The lower ends of the hooks 29 are formed to engage over alined bushings I2 of the double-strand chain Il, as will be clear from Fig. l,

In use, the chain I I is wrapped around the object to be elevated in the manner shown in Fig. l, the hook I8 of the lever I'I is engaged over bushings I2 so that the lever I1 will extend generally horizontally and radially of the object I9, the hook' 29 isengaged with the chain at the opposite side of the object, and the object is lifted by the application of tension to the cables I9 and 23. Whenthe object has been elevated and secured in the desired position, the cables are slackened and the hooks I8 disengaged from the chain. l Under the influence of gravity, the chain drops free of the object, the free end of the chain passing over the object from right to left. When the chain is free of the object, its weight will be divided between the two cables I9 and 23, which then may be permitted to descend under the inuence of gravity.

' lBecause the hooks I8 can be engaged with any ofthe bushings of the chain, the sling is adapted to grip objects of Various sizes. However, when the circumference of the object to be gripped is less than the Veffective length of the sling, some provision must be made for preventing the excess lengthof. chain from interfering with proper functioning 1 of the hooked lever I1. For this purpose, the chain illustrated in Figs. 1 to 4 of the drawings is connected tothe hooked lever I'I through the use of links or straps 3| which are secured to the end'bushing links of the chain by a'pin 32'and which, beyond such pin, are offset outwardly with respect to each other so that the space between themV will' be great enough to receive the free end of the chain, Vshown sectioned inFig. 4. The opposite ends of the links 3| are secured to the lever I1 by a pin or rivet 33, spacing collars 34 being positioned upon such pin to space the ends'of the linksv 3I from the side of thelever.`

"The modiedsling-tightening lever 40 shown in Fig. comprises abody portion adapted to extend generally radially from the object I0 and provided at its outer end with holes for the reception of the bolt by means of which it is connected to the associated cable I9.l At its inner end, the lever 49 is provided, for each chainstrand, with two vertically spaced hooks each of which is adapted to engage transverse elements of the chain. Il, The upper one of such hooks, indicated at 4l, opens obliquely inwardly and downwardly, while the lower hook 42 opens outwardly.

In using the lever 40 shown in Fig. 5, the upper hook 4I is engaged with one end of the chain, and the latter passes upwardly over and around the object I0, the lower hook 42 engaging the chain at Such a point that the lever will extend generally horizontally at one side of the object I0 so =andere that an upward effort applied to the cable I9 will tighten the sling. The cable 23 (not shown in Fig. 5) at the opposite side of the object is connected to the chain, as by the hook 29, in the manner shown in Fig. l. After application of the sling, the object I9 is hoisted and secured in elevated position, whereupon the cable I9 is slackened and the hook 4I disengaged from the end of the chain. By further slackening of the cables, the sling may be permitted to descend, that end of thev chain previously secured to the hook 4I passing over the top of the object I0. As in the arrangement shown in Figs. l to 4, the weight of the descending` chain is divided between the two cables.

When a hoist embodying the sling of Fig. 5 is to be used for successive elevation of objects I0 of the same size, the hook 42 is left permanently in engagement at the proper place with the chain II. By properly shaping the exterior of the hook 42, the possibility that such hook may accidentally become dislodged from its proper place of engagement with the chain may be reduced; but in any situation where the sling is liable to be used repeatedly to hoist objects of the same size, it is desirable to provide the lever 4D with some releasable means for holding the hook 42 in engagement with the chain at the desired point thereon. The means shown in Fig. 5 comprises a disc 43 rotatably mounted on the body of the hook 49 in position to engage the ends of the side plates associated with a bushing I2 entering the slot of the hook and thereby interfere with movement of such bushing into or out of the slot. This disc is relieved at one point, as indicated at 44, so that when the relieved portion of the disc is in association with the slot of the hook, clearance is provided for the side plates. After the hook 42 has been engaged with the chain, the disc 43 may be rotated slightly so as to prevent the hook from' leaving the chain. If the relief is provided in a form of an arcuate notch, Vas indicated, so that the disc will necessarily be rotated as a bushing enters or leaves the slot of the hook 42, the latching action of the disc will be made more effective.

, The sling-tightening lever illustrated in Fig. i

6 is substantially the same as that shown in Fig. 5 except `for the fact that'the hook 4I is elimi- 0 nated and the chain-end permanently secured to the lever as by a pin or rivet 46. This construction has the disadvantage that when the sling is released from the object after elevation of the latter, either the lever 45 or the full length of the 5 chain must pass across the top of the object. In the former event, clearance for the lever 45 would have to be provided, and the cable I9 would be carried'across the object I9 with the lever 45, thus placing it out of position to lift the next succeeding object. If the lever 45 and cable I9 descend without crossing over the top of the object, it would be necessary to disconnect the other hook 29 from the chain to prevent its associated cable from being carried over the object I0; and with 5 that hook disengaged, there would be no weight on the cable 23 to cause it to descend.

AAny of the hooks 29 and levers IT, 49, and 45 can be made of solid, one-piece construction; but it may be desirable in certain instances to form m the hooks and levers of laminated sheet-metal stampings, as clearly shown'. in Figs. 2, 3, and 4. In the case of the lever Il, I employ two sets -of laminations 59 which extendvfor the Vfull length of the lever` and which are *formed* with lthe 5 heOkS. I8 .et one en@ and with h'oles'ferthe 1e,

ception of the pin 2D at the other. Between the two sets of laminations 53, there is a third and shorter set 5I which serves to space the two -sets 5!! the proper distance apartv so .that the hooks I8 thereon may engage alined bushings of the .double-strand chain. The pin or rivet 33 passes through all three .sets of laminations, and serves tohold them together; but -i-f desired; one or more additional rivets 5,2 passing through all three -sets of laminations may be used. vIn the case of the hooks 29, each hook may be built up of identical laminations, the two sets being held in properly spaced relation Aby the use of the kpin orfrivet 3i?. The pivot pin 3|, which desirably Yhas a press -fit within the hooks, serves to prevent any independent rotation of the individual laminations `about the axis of the rivet 3,0. As will be apparent from Figs. 1 to 4, the various laminations all lie in vplanes parallel to the forces imposed on each element (hook or lever)l built up from such Vlaminations. As a result, each laminated element is substantially as strong as 'if made in one piece of the same material. Practically no relative movement of the sling parts occurs when the `sling is under load, so that any tendency to wear is extremely slight. Moreover, since the sling is self-tightening when under load, any wear that does occur is unimportant. For all these reasons, hooks and levers built up of laminated sheet-metal stampings are as satisfactory for practical purposes as if made of onepiece construction and possess the distinct present advantage that they can be manufactured without using machine-tool equipment of types in which serious shortages now exist.

Any number of the slings described may be used at points distributed along the length of the object II! to be hoisted; but where that object is not of excessive length, a single sling disposed in or near the transverse plane of the center of gravity may be employed. Where an irregularity, such as the lug 55 shown in Fig. 7, would interfere with the application of the sling at the transverse plane containing the center of gravity, I may employ on the sling a bridge 55 adapted to straddle the lug 55 and bear at its ends against the sides of the object I0. As shown, the bridge 56 is tubular in cross section and the chain I passes through it.

Slings embodying my invention are not limited to use in association with two-cable hoists where the sling-tightening lever will project generally horizontally from one side of the object being lifted. Thus, as indicated in Figs. 9 to 12, such a sling may be used with a single-cable hoist where the lever will be disposed above the lifted object. If the sling is to be used with a single cable hoist, it is desirable to so proportion the lever that its point of attachment to the cable is displaced from the perpendicular bisector ofthe line joining its points of attachment to the chain, as is the case in all the levers indicated.

When the sling is used with a single-cable hoist the lever may operate in either of two different ways depending upon whether the effective length of the sling -is small enough to maintain the lever in contact with the object being lifted (as in Figs. 9 and 11) or great enough to permit the lever to move away from such object as in Figs. 10 and 12. In the former event, the lever fulcrums about its point of contact with the object being lifted and tension in the cable tightens the sling in much the same manner as when the sling is used with a double-cable hoist. In the latter event, since the two forces applied to the lever by the chain are necessarily efiual and since their resultant must be verticalto oppose cabletension, the two chain-stretches ,extendingv away from the lever are disposed at equal angles to the Vertical and tensionin the chain will equal onehalf the load multiplied by the secant vof onehalf the anglebetween such two .chainestretches Ifhthe Apoint atv whichthe lever is connected to the cable vis spaced from the perpendicularbisec-J tor of the line joining the two-points at which the lever is vconnected to the chain,'the latter :line will be displacedangularly from the position it occupies when the effectivelength of .the sling is a maximum. In other words, as a result 'of the dis-1 placement referred to the effective length of the sling is reduced, thusincreasing the angle between the two change-stretches and increasing chaintension.

In Fig. 13, I have illustrated a sling-tightening lever I similar to that embodied in the sling'of Figs. 1 to 4. Inthis instance however `the sling comprises two independent, single-'strand chains 6I) lwhich are respectively connected, through the medium of straps 5I to the ends of aboltor pivot pin 62 passing through /thelever ITI. Collars 53, disposed on the pin ,'62 on opposite sides `of the lever il space the ends of' the chains 6il-far enough apart to permit the bodies of the chains to be engaged by the hooks I8 and to pass downy wardly between the two chain-ends after embracing the object which is to be lifted. Where the width and pitch of the chains 60 are small compared to the diameter of the object to be lifted, it is possible to distort the chain from a single plane to an extent sufficient to produce the result indicated in Fig. 13.

Wholly apart from the form of chain-tightening lever used, slings of the type illustrated possess several advantages. Since the pins Ill are always held in substantially parallel arrangement no matter to what extent the chain is flexed in a plane perpendicular to the pin-axes, the relatively narrow edges of the side plates I3 or I Ei are presented to and engage the surface of the object I 0. Because of this, the gripping effort of the chain is concentrated at points each of very small area; and at those points the sling tends to bite into the surface of the object being lifted, thus effectively opposing any tendency of such object to slip through the sling. The fact that the chain is relatively rigid against deiiection other than deflection in the plane perpendicular to the pin-axes facilitates positioning the sling longitudinally of the object to be lifted, and also tends to oppose tipping of that object should the sling not be accurately positioned at its balance. Further, even if the sling is accurately located at the balance of the object being lifted, the rigidity of the sling-chains against sideways bending opposes any tendency of 'such object to oscillate or ,f

rock. The short and uniform spacing of the hook-receiving openings in the sling chain facilitate engagement of the hook or hooks on the chain tightening lever and adjustment of the sling to grip objects of different size.

It will be noted that in each of the chain-engaging hooks shown the outer surface of the hook,

- for a considerable angular extent, is substantially concentric with the chain-bushing I2 which the hook engages and that its radius of curvature is such that the hook-body substantially iills the space between adjacent chain-bushings I2. As a result, each chain-tightening lever must be brought into a particular angular relationship with the chain-link which is to receive the hook before the latter can be inserted or removed.` 'The opening of each hook is sopresented that when the sling is under load the chain-tightening lever and the link which receives the hook. will be so angularly disposed thatJ disengagement of the hook from the chain is impossible. Thus, for example, with the hook I1 under load, as shown in Fig. 1, the hook I8 cannot become disengaged from the chain bushing I2 it receives because of engagement of the upper surface of the hook with the next bushing I2 immediately above it. Moreover, the tension in the cable I9 tends to swing the lever Il in a direction opposite to that in which it must move before disengagement of the hook I8 from the chain can be effected. This makes for security in that it insures that the lever cannot become disengaged from the chain when the sling is under load.

I claim as my invention: Y

1. A hoisting device, comprising a iiexible chain having a series of longitudinally spaced transverse elements, a lever, one end of said chain being connected to said lever, said lever being provided with a hook engageable with any of said transverse elements to retain the chain in position embracing an object to be hoisted with the lever projecting generally radially from such object,` a hoisting member connected t0 said lever near the outer end thereof, said hook and the points of connection of said lever to said chainend and hoisting member being so arranged that lifting eiort applied to the hoisting member will tend to rotate the lever and tighten the chain on the object it embraces, a second hoisting member and a hook on said second member, said last named hook engaging said chain at a point approximately opposite said lever.

2. A sling, said sling comprising a flexible chain having a series of spaced transverse elements, and a lever for tightening said sling on an object located Within it, said lever extending outwardly fromfsaid sling and having at its inner end two hooks for engagement respectively with transverse chain elements, one of said hooks opening inwardly of the sling and the other opening outwardly, said lever being adapted at a point near its outer end for connection to a hoisting member.

3. The invention set forth in claim 2 with the addition that the point at which said lever is adapted for connection to the hoisting member is nearer to the base of said outwardly opening hook than to the base of said inwardly opening hook.

OLIVER H. GALLAMORE.

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