US2850316A - Load-transfer cable equipment - Google Patents

Description

Sept. 2, 19.58 D. J. PHILIBERT 2,850,316

LOAD-TRANSFER CABLE EQUIPIVIENT` Filed Maron 27. 1955 United States Patent ce 2,850,316 @talented Sept. 2, 1958 2,850,316 LOAD-'IRANSFER CABLE EQUIPMENT Dollard J. Philibert, Meriden, Conn. Application March 27, 1953, Serial No. 344,984 15 Claims. (Cl. 294-74) This invention relates to load-transfer cable equipment; and it relates more particularly to equipment of this kind characterized by the employment of a load loop or cargo loop that is non-collapsible by reason of its including bracing means, most desirably a spreader device which is itself also of novel type, acting to maintain said loop at all times open a minimum distance or width even under maximum load conditions. The invention is of especially great utility in connection with apparatus for the loading and unloading of ships and other cargo or freight carriers, for example.

In transferring heavy objects or loads of material from one location to another through a relatively short distance, as for example in transferring cargo from dock to ship or from ship to dock, it is common to make use of a crane or derrick of some description which, in whatever specic form it may take, includ-es hoisting tackle carried by a swingable arm or boom. Such tackle includes a stranded steel wire rope or cable reeved through a pulley block secured to the boom and having one end made fast to the winding drum or barrel of a poweroperated winch, While the other end portion is formed to provide an eye or loop, which may be on the order of 2 or 3 feet in length under no-load con-ditions, by splicing or otherwise securing the cable end to the cable at a point thereon far enough back from said end to give a loop of the desired length. To the opposite or rounded free extremity of the loop thus formed is secured by appropriate fastening means of some kind, such as a shackle, a load or cargo hook which releasably engages, or from which is releasably suspended, the load to be hoisted and transferred. A

Crane or derrick `equipment of this general type is widely used in stevedoring operations, for example, where it isrsubjected to extremely rough usage. Although the load required to be handled at one time in such service does not ordinarily exceed about 5 tons dead weight,

standard safety regulations require that the wire cable employe-d shall test at least 20 tons breaking strength. This is because, due to sudden starting or stopping of the winch, often through careless operation, or to any of various other causes, the strain -which the cable is actually called upon frequently to withstand momentarily under such severe service conditions often greatly exceeds 5 tons. A 'Xs-inch diameter hoisting cable of twisted steel wire strands is commonly employed in such equipment.

Despite the considerable stiffness and resiliency of such a cable, whereby it strongly resists being bent at a sharp angle, the cable is flexible enough to permit its being readily bent on a reasonably long-radius curve, as in forming the end of such above described terminal loop. Under heavy load, the cable loop naturally elon! gates and narrows more or less. Upon release of the load, the loop normally tends, because of the rather sti resiliency of the cable, to spring back immediately, undamaged, into its original more rounded or widely open form and shorter length. However, if through careless operation of the power winch, for example, the cable is given a quick jerk in lifting or arresting descent of a heavy load engaged by the cargo hook, the resultant large force suddenly concentrated upon the cable, acting transversely thereof within the relatively small surface area thereof contacted by the shackle at the lower extremity of the loop, may cause the cable to be bent so sharply at this locality as to narrow or collapse the loop considerably or, in extreme but by no means uncommon cases, to close it virtually completely. Where such virtually complete closure or collapse occurs, the result is not uncommonly such acute-angle permanent deformation of the loop at its lower end as to require forcibly wedging apart the thus frozen loop sides or branches, in order to open the loop suiciently to free the shackle. This is because, at the vertex of such angular deformation, the cable strands have been stressed by the sharpness of the bending or ilexure beyond their elastic limit and have taken a permanent set. Wedging the loop sides apart and thereby partially reversing this acute bend in the cable necessarily results in serious strand weakening and more or less strand breakage at the bend, an effect externally evidenced by fraying of the cable surface at this locality. Considerations of safety require that the entire loop thereupon be cut off, and a new loop spliced in the cable as before described.

But even where a sudden jerk or quick pick-up of the load is not heavy enough to close the loop but only to narrow (and elongate) it to a lesser degree not resulting in too sharply bending the cable at the curved lower extremity of the loop, the severe conditions under which the equipment is normally required to operate in actual service necessarily involves constant recurrence, over and over again of (l) narrowing or partial collapse of the loop under applied load, alternating with (2) rebound or spring-back of the loop into the more open or rounded form in which the inherent springlike character of the steel cable tends, so long as the cable does not become permanently bent at the loop vertex by local over-stressing at this point, constantly to maintain the loop open. Consequently, when such a cargo loop' is in use, there is always occurring at its shackle-engaged extremity a back-andforth bending movement of the cable strands in greater or less degree, due to the alternating load pick-up and load release. This cycle of alternating transverse bending stresses occurs a very large number of times in one ordinary days operation of such equipment. It is also accompanied, naturally, by considerable friction between the twisted wire strands. All this eventually results in metal fatigue, wear and more or less breakage, externally manifested by surface fraying at the aifected locality. Under the severely rough service conditions encountered in stevedoring operations, this effect is often produced in a surprisingly short time. Here again, even though such complete loop collapse as to freeze the loop branches together may at no time have occurred, the appearance of fraying is the signal rendering it mandatory to cut oir" of the cargo loop and splice a new one.

While the strand-deteriorating effect produced at the lower end of the loop by the cyclical back-and-forth or inandout movement of the loop branches has been more particularly stressed hereinabove, it should be noted that this effect may be produced also at the upper or spliced end of the loop, although generally in much less noticeable degree.

Not only does the necessity for relatively frequent replacement of a damaged cargo loop entail loss of time and consequent expense by reason of the interruptions in equipment operation thereby necessitated, but an even more important consideration is that, for any given hoisting cable, the number -of times it is possible to cut olf a defective or unsafe loop and to re-loop a further portion of the cable by splicing as described, is small. After only a few such loop replacements, the cable, although it may still be perfectly sound, has become useless for further service in such equipment and must be discarded. This is because its length has reached the minimum at ment involved. Such cables, being Yfabricated of high grade steel wire,;are costly. Their relatively short service life in such equipment gives rise, therefore, tol a frequently recurring expense item of substantial magnitude.

The lengthlimitation just referred to arises from the fact Ythat the pressure exerted upon a layer of cable turns on'the winding drum of the winch by succeeding layers wound thereonurider heavy load tension is so Vgreat that it is not practical to have the cable sufficiently long at the Vstart t-o provide more Vthan a relatively very small reserve fon 'the winding drum. It a greater reserve Vwere provided, thus materially prolonging the time beforek progressive shortening of the cable by loop replacements would require paying out and re-windingV the lowermo'st layer or layers of the reserve cablewturns, these turns would have become so set or fixed in curvature by theaforesaid pressure of superimposed layers that serious lrinkingtof the cable would result from any attempt to pay them out and re-wind them, as part oi"V the necessary working length of the cable. For this kmovement of the loop sides or branches toward each Y other, insuicient to cause excessive bending or Yiexure of t Y the cable under load, is permitted. Y

While the invention may be embodied in various specie forms, one especially desirable practical embodiment thereof isV shown, by way yof illustrative example, in the accompanying drawings, wherein Fig. l showsfthe hovelcable loop construction in side elevation, with attached cargo or load hook, the parts being in no-load position; 1 Y

' Figs. 2 and 3 are enlarged sections Ion the lines 2-2 and 3'-?a,'rrespectivre'ly, of Fig. l;V .t Fig.' 4 is a section, partly in elevation, on the hne Y of Fig..V 3, but with the parts in the position asreason, hoisting'cables of the type here in question are supplied by the'manufacturers in standard lengths varying, of course, with the particular equipment set-up in which they are designed to be used, the cable in any given Vinstance being of a length not much exceeding the working length required for the particular set-up aforesaid.V VAn over-all length on the order of 175 feet or thereaoouts for a new cable as supplied by the manufacturer represents common practice in'stevedoring work. Another difliculty incidental to use of cargo loops heretofore available has'been the severity and sharpnessV of the shocks to'which the cable as a whole is sub- Y jected, and lwhich are transmitted by the cable -to fthe Y' blocks'on the derrick as well-as to the power winch and -V other equipment parts, du'e to sudden pick-up ofheavy loads andthe resultant quiclV narrowing or collapsing (partial or complete) of the loop to its Vnal load position. VThis 'is very hard on the equipment as a-whole, necessitating frequent shutdown for repairs and `causing rapid deterioration.

- An important object of the present VVA further object of the invention is, lby thus prolongiiig the, service life of such a cable loop, to ,render replacement; of the cable as a whole less frequently neces` sary. l t i Y Still another object of the invention is to'enable lessening V.the intensity or sharpness of stress shocks impartedV Y to the cable and the equipment with which it is associated by the sudden pick-up of heavy loads attached Yto Y ythe cable loop, thereby materially cutting down over-all wear and tear.V t

More specifically, it is any object of the invention to Y provide Ya novelrtype of cable loop construction whereby invention is, theretore, to prolong substantially the service life of a cable Yloopofrthe general type hereinabove referred to, particularly kof cargo loops such as those widely used in Ystevedoring operations. Y Y

sumed under load suiciently great to narrow the cable loopto the minimum width permitted by the stilening Y or bracing means; n

Fig. 5 is a fragmentary view in side-elevation, looking in the direction of arrow Y5 in Fig. `4; and

t Pig. 6 is another fragmentary view in side elevation, lookingih the direction of arrow 6 in Fig. 1.

Referring to 'the drawings, and more particularly to Fig. `l thereof, 10 designates generally a loop on a ilexibleY hoisting cable 12, which in this instance is formed of twisted-steel wire strands. The Vloop 10 is usually formed of a length of the flexible cable itself bentinto loop form and having its end suitably secured tothe cable, iii'this instance by splicing as indicated at 13. A

secured inthe usual mannerto the lower extremity of Y th'ec'able loop for free swinging movement with respect thereto by suitable fastening means such as a shackle of well-known type indicated generally at S (Figs. l and not occur, and that said movement takes Vplace. lessV abruptly .than with cable loop .constructions heretofore known. Y

' In acoordancewith the-principles of the invention, the foregoing objectsrand attendant'advantages, as well fas others which will become apparent hereinafter, are 'at-V cable loop of the characterV de-f eribed with stitening or bracing means, Vmost desirably Vin the formof a compressible spreader device, extending transversely of the loop and engaging the cable at the Y 'opposite sides or branches 4of the loop; the arrangement Y being such that complete closure orcollapse ofthe loop tained t byY providing a under Vload tension is positively prevented, Vwhile limited 6). TheV cable Vloop is rendered ynon-collapsible under loadtension by'bra'cing or stiffenihg means, indicated generally at 14, extending within the vloop crosswise thereof and terminally secured to the cable at opposite sides of saidloop at an intermediate location in its length.

Said' bracing or stiffening means functions to maintain the loop armsY or branchesrpositively spaced or spread apart at least a predetermined minimum distance at the t location where it is placed in the loop, regardless of the the loop and the cable as a whole load tension to which may be subjected;v

Y Y As hereinabove indicated, the bracing means or spreader device 14 is most desirably compressibleto a limitedextent between the loop arms or sides by the inwardly directe'd thrust they exert upon itV whenjthe loop is subt jected to heavy load tension, thereby-tending to narrow or even collapse the loop. As here shown, therefore, and referring moreparticula'rlyto Figs. 2 and 3, Vsaid means 14Vcomprises two telescopin'g Vmembers 18 and 2.0,V member 18 having a tubular portion openr at one end 22, while the cooperating member Ztlhas a portion formed as Va plunger iitting and axially Vslidable within the tubular portion of member 18. Within the ,tubular portion of member 18,7a compression-type coiled spring'30 of Suitablypheavy gauge steel 'wire is Vconinedrbetween the bottom 24 of'said tubular portion and the annular shoul- Vder 28 on plunger 20, Awhose forwardly projectingY reduced portion 21v serves, in yconjunction with theadjacent wall of member 18,-to prvide an annularrecess'26.

In order to limit positively theextent to which theV spreader device isfcompressible by inward pressurey or thrust of theY cable loop sides Vagainst its ends, as well as to prevent separation of the telescoping members 18 and 29. by the action of., the spring upon cessationbf Ysuch thrust, the

` plunger Y20 is in this instance provided Vwit-h a longitudinally'extending'diametral slot 32, through which and also through aligned apertures in member 18 adjacent the openV end 22V thereof extendsa cross-pin 34, whose ends are peened or headed over,'as Vshowntin Fig. 3, to

prevent its being accidentally dislodged: v In the fully t expanded conditionV infrwhich members VV`18 and 20 @are shown in Figs. 1-3, the spring 30 is already somewhat compressed. In this condition, engagement of cross-pin 34 with member 20 at the left-hand end of slot 32 positively prevents further expansion of spreader 14 and hence, also, any further widening of the cable loop. On the other hand, in the fully compressed condition shown in Fig. 4, further contraction or shortening of the spreader, with further narrowing of the cable loop is positively prevented primarily by abutment of the annular end 70 of member 18 with the annular shoulder 72 provided on member 20, also by reason of the fact that cross-pin 34 yis now at or near the opposite end of slot 32. Shoulder 72 and a cross-pin 34 in slot 32, therefore, comprise stop means for positively preventing compression of the spreader device beyond a predetermined limit.

Referring now to further desirable structural features of spreader device 14, the telescoping members 18 and 20 are provided at their outer ends with outwardly projecting shanks 36 and 38, respectively, which are adapted to bear against the opposite sides 16 of the cable loop 10. In order to atord maximum seating area for the loop sides 16, the ends of the shanks 36 and 38 may be concavely rounded or grooved as indicated at 37 (Figs. 2 and 3). The members 18 and 20 are further provided with shoulders 40 and 42, respectively, against which bear the internal shoulders 44 of knurled coupling nuts or sleeves 46 and 43, respectively. There are further provided two identical clamping plugs or yoke- pieces 50 and 52, each of which is externally threaded at 54 for releasable connection with the adjacent nuts 46 and 48. Each of the plugs 50 and 52 is provided in one end thereof with round-bottomed open recess or groove 56 of a width sutiicient to accommodate the cable and of a depth considerably greater than the cable diameter. The rounding of the bottom of the groove 56, as at 58, is in order to afford maximum seating area for the cable forming the loop.

In applying the brace, strut or spreader device 14 to the cable loop, the plugs 50 and 52 are removed from the nuts 46 and 48 and the device is placed between the loop with the ends of the outwardly projecting shanks 36 and 38 of the members 18 and 20 bearing against the respectively adjacent inner faces of the arms 16 of the cable loop. The plugs 50 and 52 are thereupon positioned with their grooves 56 over the loop arms and then connected with the adjacent nuts 46 and 48 by turningV the latter. By tightening the nuts 46 and 48, the rounded groove bottoms 58 in the plugs 56 and 52 and the complementarily grooved ends 37 of the shanks 36 and 3S of the members 18 and 20 are drawn into firm clamping engagement with the cable at opposite locations on the loop arms, as shown. The spreader 14 is now rmly anchored to the loop at a location intermediate its upper and lower extremities. sharp bending of the cable is greatest at the lower extremity where the loop is engaged by the shackle, spreader 14 should ordinarily be located, as shown in Fig. l, somewhat closer to the lower extremity 62 of the loop than to the upper.

The yielding contractibility of the spreader device 14 is an important factor in prolonging the useful life of the cable loop. By reason of this characteristic, the device acts as a very efficient shock absorber which functions to especial advantage when a load is picked up suddenly. Thus, a considerable part of the initial shock of a sudden load pick-up is taken up and absorbed by the spreader device instead of being almost instantly transmitted with full intensity to the cable loop, the cable as a whole, and the associated operating equipment. In this connection, the limit imposed upon the yielding contractibility of the device 14 is of'further advantage, in that the latter will' under no circumstances permit flexure at the curved extremity 62 of the cable loop much beyond that indicated in Fig. 4, even if a heavy load on Because the danger of too a sudden or jerky pick-up should quickly contract the spreader to its minimum length.

By appropriately varying the design of the spreader device in respect to type and characteristics of its shockcushioning member (specifically spring 30) employed and/or other constructional details, in a manner obvious in view of the present disclosure, the degree of resistance offered by said device to inward thrust of the loop arms, as well as vthe range within which variations in loop width are positively confined, can be predetermined as may be necessary to meet the requirements of any particular situation involving equipment of the general character here in question. For the usual -run of stevedoring work, it is good practice to so construct said spreader device that an inward or horizontal thrust against its ends amounting to at least about 500 pounds must be exerted by the loop sides or branches in order to compress or contract the loop to minimum predetermined length as illustrated in Fig. 4.

The ease with which, through provision of the releasable cable clamps, the position of the spreader or bracing means on the loop may be quickly shifted so as to afford maximum protection against dangerously sharp flexure of the cable in a given equipment set-up or under given operating conditions, is a valuable feature of the novel load or cargo loop construction.

The invention may be carried out in specic ways other than those herein set forth without departing from the spirit and essential characteristics of the invention. The present embodiments are, therefore, to be considered as being only illustrative and not restrictive, it being intended that all changes coming within the meaning and equivalency range of the appended claims shall be embraced therein.

What is claimed is:

1. Load-transfer cable equipment, comprising, in combination, a exible and resilient stranded wire cable having an end portion formed into a load loop which has a curved extremity that is adapted for attachment of a load thereto, together with loop-bracing means extending across said loop intermediate its extremities and terminally secured to its opposite sides; said `bracing means having shock-absorbing means compressible -under inward thrust of the cable at the loop sides to yieldingly resist narrowing of the loop under load tension, said bracing means being provided with stop means for positively arresting such narrowing of the loop beyond a predetermined limit to prevent unduly sharp bending of the cable at said curved extremity.

2. Load-transfer cable equipment comprising, in combination, a flexible and resilient stranded wire cable having an end portion formed into a load loop which has a curved extremity that is adapted for attachment of a load thereto, together with loop-bracing means extending across said loop intermediate its extremities and terminally secured to its opposite sides; said bracing means having shock-absorbing means compressible under inward thrust of the cable at the loop sides to yieldingly resist narrowing of the loop under load tension and stop means for positively arresting such narrowing of the loop beyond a predetermined limit to prevent unduly sharp bending of the cable at said curved extremity; said bracing means being further provided at each end with a clamp comprising parts separable to engage the cable between them, and means for connecting said parts and causing them to grip such cable firmly.

3. Load-transfer cable equipment as set forth in claim 2, wherein such shock-absorbing means comprises members telescoped one within the other, a compression spring interposed between them to yieldingly oppose relative movement thereof to contract or shorten the brace, said stop means limiting such contracting movement, and stop means limiting relative movement of said members to lengthen or expand the brace.

4. Load-transfer cable equipment comprising the coml"7 Y bination, with a'resilient steel cable Yhaving la terminal portion self-spliced to form acargoloop having a normally'rounded lower extremity, together with means for 7 attaching a load to said lower extremity, said meansincluding a member having'a portionof Vsmall surface area in engagement with said lower extremity of the loop such thatsudden pick-up of a heavy load tends to collapse the p looppandthereby to bend its said extremity out of the latters normally rounded form and into relatively angu- Vlar form, of strut orV brace means extending Ytransversely across saidloop and secured to said cable at the opposite.

sides or branches of Ysaid loop to prevent Ynarrowing of Ythe loop beyond a predetermined limit, said'brace means comprising telescopically cooperating members relatively Vmovable with respect to each other transversely of said loop without affecting the securement of the brace means to Vsaid cable, wherebyrtorpermit variation ineffective length of` said brace meansy and hence of the loop widthV under varying load conditions, said brace means further including' stop means limiting such relative' movement ofrsa'id members.

5.V Load-transfer cable, equipment comprising the comsecurelyA clamped between them; saidjbrace. comprising t members telescopedone within the other, acompression spring interposed :between them to yieldingly oppose vrela- 'e tivemovement thereof `to contract or shorten thebrace, stop means limiting such contracting movement,` and stop means'limiting'relati-ve movement of saidfinembersV to lengthen or'expand the brace.V f Y i 9. A spreader device as set forth Vinfclaim 8, wherein the Y telescoped members'are pin-and-slot connected, Y A l0. YA spreader device as set forth in claimV 9, which further includes shoulder `means provided on one ofsaid Y telescoped members for engagement with the other-0fY said members and in order to stop `brace-shortening relative movementof said members. Y

Y1l. A Yspreader Adevice for bracing Yand stabilizing a loador cargo-loop of a load-transfer cable, whichcomprises a longitudinally'compressible braceYV adapted to .extend across the loador cargo-loop 'of'a' load-transfer cable between the sides thereof, and aV releasable cable-` clamp at each end of said brace .operative to 'griplthe cable at the opposite sides of said loop irrespective of the extent to which .said brace may .be compressed, and wherein said brace has Aa laterallyprojecting shoulder adjacent each. end thereof, .while each cable-clamp comprises .an externally threaded plug provided with a transverse ret cess wide enough to receive .the cable and deeper than the narrowing of the loop beyond a predetermined limit, saidY brace means comprising ycooperating membersV relatively movable withV respect toV each other transverselyofsaid loop without aecting thesecurement ofthe brace Ameans to said cable, whereby toV permitvariation in eective length of said -brace means and hence of Vthe-loop width under varying load conditions, said brace meanspf-urher including stop means limiting such relative movement of Vsaid membersgsaid equipment being further characterized by Vthe fact that the brace means-is secured to the cable Vat each side of the loop by Yclamping meanslcomprisinga threaded yoke-piece which engagestthe cableY externally of the loop in alinement with the adjacent brace member,"and a coupling nut rotatable upon such Vbrace mem-Y ber, retained thereon by suitable abutment means, eng'a'g-` in cooperation therewith to clampfthe cable between said y,yoke-piece and said ybrace member',Y

f 4, whereinV the load-attaching includes' a shackle e ing the threaded portion ofsaid yoke-piece and `operable Vandthe en d ofthe brace.

cable diameter, together with a-coupling sleeve which is rotatable on said brace, which is provided internally with a shoulder adapted, upon outward movement ofthe sleeveY along said brace,=to engage the adjacentbraceV shoulder for arrest yof such movement, and whichy is internally threaded/forconnecting engagement with the threaded"r4 portiontof said plug; whereby -upon the thr'eaded sleeve f being so engaged with receivedtin'said'transverse recessand upon said sleeve: being turned to Vtighten the coupling connection thus.- made, the cable is firmly clampedbetweenesaid plug l2. Arspreader device as set forth-in claim l-l`rwherein ysaid'brace comprises al member having a tubular portion closed -atone end only, a plunger member longitudinally y slidable in such tubular portion and extending outwardly Ybeyond the open end thereof,and a compression spring..

in said tubular portion interposedV between the closed end thereof and said plunger member.

l3. A spire der device' as set forth inclaim'ilrZgwhere-jlin ,the end Yfaces of said brace and the bottom oftheftrans-V member engaging the lower extremity of said loop, and e wherei'npcompressible means is interposed between the relativelyY movable members of said brace. vmeans and V1s arranged yieldinglyto resist shortening of` the effective length `of said braceV means before said stop means for limiting such relative movement of said membersV cornesY l into action. Y

7. .A spreader device for bracing and stabilizing aY load orcargo loop of a load-transfer-cable, Vwliich'comn Y prises a longitudinally compressible brace Yadapted to extend across the load or cargo loop of a load-transfer V cable between the sides thereof, with its endsconcavely rounded for terminal engagement with the cable internally -o'fY the loop, a pair of members each recessed yto tit over the cable externally of the loop in alinementrwith said brace, andr coupling means operable to so connect each recessed l mem-ber with the adjacent braceend that the 'cable jis securely clamped between them.

8.V A spreader device for braclng and stabilizing a load.V

' or cargo loop. of a load-transferfcable, which comprises a longitudinally compressible brace'adapted to extend across VYthe "load orcargo loop of aloadtransfer 'cable between the sides thereof, with its ends'concavely yrounded for terminal engagement with the cable internally of the loop,-a,pair of members yeach'recessed topt over the cable externally of the loop VVin alinement with said brace, and coupling means operable to so connect, each reeessed member withthe adjacentV brace end that the cable is.

verse recess of each said plug areconcavely curvedfor effective `clamping engagement ofthe cable between them.Y 14.` A-spreader device as set forth'` in claim 13, wherein said plunger member has an external shoulderadapted and arranged to abut ,the open end of said tubular portion. ofthe other member` after the brace has been-compressed to.V a predetermined fextent, whereby to. prevent further shortening thereof. i L Y' .Y l5. A spreader device as 'set forth in claim 14,/ where-V in said spring is pre-compressedin the predeterminedfull length condition of said brace, said 1oracemembers being p'in-and-slot'connected Vto prevent lthe pre-compressed spring Vfrom expanding the brace beyond saidpredetermined .fu1l'length, while permitting compression -of the brace from its full lengthr'to predetermined Y Great Britain alan, 20, 14927 the threaded plug after the'cable length. t e

References Cited in the file of this patent e ',.uNrrnD VSTATES 'PATENTSV Y Y -V 194,448 Y tenue l i Aug. 21, 1877 t 1,229,705 Bolus g- June l2, 19.417 1,444,754 Y Pruden 1 en Feb.6', 1 923' .1,655,744 SwanbyY p Jan. 10,1928V 2,643,109V f wood Y Y Y V June 23,1953

. FOREIGN .PATENTS 1 Y v'675,502 Germany en May'f10,f19}39 r *7264,263

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