US1917147A - Cable clamp - Google Patents

Description

Y rJuly 4, 1933- J. K. osTRANDER CABLE CLAMP original Filed Jan.

PatentedV July 4',` 1933,

UNITED. ASTATES JOHN K. OSTRANDER, for PHILADELPHIA, rinviasYLvAixIAy f CABLE CLAMP Application flied January 12'1931, Aserial No. 5:18307. Renewed May 18, 1933.

One object of the invention` is to provide.

aV cable-'gripping clamp in which the gripping force is automatically regulated by the Weight of thatportion of the cable supported by the individual clamp. i

Another robject of the invention is Vto provide a cablefsupporting clamp of thestated character having an automatic safety feature, in that increase of the load applied to 4the cla-mp through the cable to a predetermined maXimum results in a partial release of the gripping force .of the clamp, permit- 5520 ting longitudinal slippage' 0f @he Cable .throughthe clamp. A n v 'Another object of the invention is to provide a clamp in which any upward movement vof the cable in the supported part has the 25 eifectof temporarily releasing the grip,'for

a purpose hereinafter fully fset forth. n Still another object of` the invention is to Vprovide a cable-gripping clamp having certain desirable self-adjusting' characteristics,

30 as hereinafter set forth.

' The invention further resides lin certaindesirable structural features and-details hereinafter'described and illustrated in the at taehed drawing, in which:' v,

Figure 1 is an end elevation of ai clamp made in accordance with my invention, and

Fig. 2 is a sidel elevational view of the clamp. A Q

With reference tothe drawing, the clamp in a preferred form comprises a pairof ,arms

1 and 2`joined together attheir lower ends by means in the present instance of a pair of bolts 3, 3, said arms being provided with aligned openings 1 and 5, respectively, which 5 receivethe trunnions 6 and 7 respectively,

of a pair of segmental cable- grippingelementsV 8 and 9, adaptedin assembly and as illustrated'in Fig. 1 to lengage the oppositel sides vof av cable 10..From a point above the openingsl the arms land 2 liare outwardly away 4from each other, as indicated at 11, and each arm at its upper extremity is provided with an opening for reception of'a pinf1'2, these pins yfunctioningto secure to each of said arms afpair of links, 13, 13 and'14, l141, respectively. These pairs of links which` preferably occupy positions onroppo'site sides of their respective associated arms 1 and 2 converge upwardly and are pivotally connected through the medium ofV a pinv 15 to a. depending arm 16.v This arm is adapted to be securedto a bank of insulators which maybe supported on or suspended from any suitable supporting structure.

The retaining bolts 3, 3 are more orle'ss free 65 'in the arms 1 and 2 to permit a certain limited adjustability of the arms with respect to each other.y The construction described thereby produces through the' medium of the arms 1 and 2, the bolts 3 andthe links 13 and 14; a 70 toggle effect wherein the weight 'of the cable 10 tends to draw the upper ends of the arms 1 and 2 together. and consequently the ' elements 8 and 9 forcibly against'the opposite sides'of the cable. The` gripping force of 75 the . elements 8 and 9 upon'the cable, therefore, varies directly with the load applied to theclamp through the cable. It will be noted,

however, that the load constituted by the cable 10 vhas a tendency to cause the upper portions 11 ofthe arms 1 and 2 tok straighten out into the positions illustrated by the broken linesin Fig, 1. By a judicious proportioning off-the said arms, it is possible to introduce into the device a critical maximum-loadsustaining factor whereby at a given maXimuni load the said arms 1 and 2 will flex into positions approximately .as shown' in broken lines. y This has the effect ofvelongating the toggle by increasing the angle at the toggle joint, and thereby correspondingly reduces the toggle action andthe effective gripping force of the elements 8 and 9 upon the clamp. When so constructed, the effective gripfof the vclamp upon the cablewill increase inl direct ratio with the increase of the load applied through the cable to a predeterminedmaximum, at-which point the gripping force is automatically decreased a predetermined eX- n tent, this reductionin the grippingaction '100 being sufficient to permit longitudinal slippagel of the cable between the gripping jaws 8 and 9 in the event that the load at opposite sides of the said jaws is unbalanced.

As a practical application of this principle, it will be understood that high tension and similar vcables are commonly-supported on l high towers placed atv reasonable intervals,

and that when oneof the transmission lines parts between any two towers, the normally balanced strain upon the adj acent towers is immediately unbalanced. In some instances,

these towers are made sufficiently streng to withstand these,V unbalanced strains, but this involves a relatively high expense in the con# struction of the towers, and for that reason is undesirable. With the' present device, the

supporting towers may bebuilt to withstand l 'a predetermined unbalanced strain, andthe varmsl and 2 of the y'clanfip may` be so con- 'structedthat they willftle-X under acorre- .spending load. Under these circumstances, :the clamp Vwill retainits normal securergrip uponithe cable under allfco'nditions except when the load upon the clamp approaches the vmaximum sustaining load yof the tower, whereupon.thefclamp will permit slippage or the cable,vinsuring a sufficient balancing kof the load upon the tower tov prevent damage .tothe latter. j i Y T g '.Ink addition tothe action described above, the device operates to relieve the towersot some of the shock resulting from therecnil of the loose ends of the cable at opposite sides of a break. The supported cables' are necessarilyv under a considerable tension which when a break occurs result-s in a heavy vrecoil of the wireat each side of the break. Where, as has previously been the practice, the cable is gripped rigidly by the clamps, vthe atoredescribed reaction is taken up entirely by the l kadj acent towers which must be built Vto withstand thisL sudden heavyunbalanced load. It ,s has been `found that theinitial recoil of the `wires has theeiiect of actually elevating the vwirewhere it is supported at the adjacent jaws 8 and `9, not sufficiently, however, to

entirely disengage the jaws fromthe cable. j

In addition to the automatic safety features described above, my invention provides a de.-

vicey of relative simplicity and low cost of manufacture which at the same time ishighly efficient in its intended function; j By mounting the clamping j awsupon trunnions as de,- scribed, the aws automaticallyadjust them,.-

selves to the normal position of the cable and thereby avoid undue strains upon the .clamp Y or upon the cable. The invention also aiifords by simple means an adjustment of the clamp to Iit cables of different diameters, this being accomplished by a tightening or loosening of the bolts 3 jaws Bland. 9L having an internal curvature corresponding to-the circumferential'dimenf sions of the particular cable to be supported'.

-ture from the invention. I -c'l'aim :V

the arms togethenadjacent their lower` ends,

,suspensionfmeansfconnected to said arms .and

There may bemodiication without deparv V1. Acarble clamp comprisinga pair of up! "wardly divergrngarms, *means-'fr securing 'andby use of clamping sov permitting movements ofthe upper, ends ofi 'di' the arms toward each other, and means fintermediate `v the endsfof saidiarms for engaging opposite sides of a cable, the diverging portions of 'saidfarrns being [so constructed 'and' arrai'iged v"t ieX .inwardly when; thefsaid load Y exceedsi .predetermined lmaximum whereby the gripping `force of saidarins upon the cable is automatically decreased.

2. In a cable-supportingclamp, ,the` i, bination with a pair 'of''.L'ipwardly.diverging-V arms,of a pairof oppositely arranged cableengaging j clamps, respectivelyV i pivotally mounted infsaid arms on axes' transverse to the direction' of the supported `cable, means forlpivotally connecting the said armsat a point below{thefgsaid c'ablefgrip'ping`y jaws, the upper ends of said arms beingadjustably secured to a supportingv structure whereby `the weight ofthe cable tends ,tn drawfthe Viippcl. ends of saidarmstogether.,

3. Acable clamp comprising afpair'ofin- `,terconnected clampingarms, andmeans for suspending the arms so thatfthey tend to draw together upon,I an interposed, cable, said arms being constructed' to bend under a prede- A l term'ined4 abnormal Htorce to decrease the clamping pressure thereof upon .the cable'. j

4. In a snepension clampvfor cables,- vthe combination' `with'a pairyot arms havingim `termediate'the ends thereof opposedcable gripping jaws," of means .for'pivotallysecuringsaid arms togetheriat a point below said jaws, said` arms comprising divergent portions above the jaws, meansfo'r suspending the arms from a supporting structure wherebythe weight :of a supported `cable inconl junction with.l the "divergent arms tends to draw: the jaws` iirmly'against the cable, and saidljdivergent' parts being jconstructed to vb'endtoward'-1each other under 'a .predetermined abnormal load to thereby decreasel the clamping'pressureon'the'cable., i

toggle suspension ron said Y, elements tending to elongateA undery l,weicht[of ,the cable, said toggledeteneiensthe pressure "Of @hesse u `5. lua 'cablefsuprertns .Clamrfth combin'ation ywith cable-gripping.elements,. oita toggles relieving a portion of the clamping pressure thereof upon the cable.

.7.l In a cable clamp, the combination With cable-gripping elements, of means including a cable-supporting member constructed, to distort under a predetermined abnormalload forreducing the gripping force on the cable of said elements when the load imposed'by the cable on the clamp reaches a predetermined maximum.,

JOHN K. OSTRANDER.

vso

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