US1660065A - Rope - Google Patents

Description

Feb. 21, 1928.

ROPE

Filed Jan. 2, 1927 w I71 U6 71 '0 1 Ellis w. Brewster MM Mr- 2' J Q'xtta 2 22296" 1,660,065' E. W. BREWSTER I 515 lay,

Patented Feb. 21, 1928.

UNITED STAT S ELLIS W. BREWSTER, OF PLYMOUTH, M

ASSACHUSETTS, ,ASSIGNOR TO PLYMOUTH COBDAGE COMPANY, OF NORTH PLYMOUTH, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

ROPE.

Application filed January 22, 1927. Serial No. 162,898.

This invention relates to improvement in rope. More particularly it provides an improvement in ordinary rope; that is, in rope consisting wholly of long and strong vege- 6 table fibres such as hemp or sisal. The invent-ion resides in the discovery of a articular arrangement of" elements by w 1i ch utility, strength, flexibility and durability are very considerably improved as compared 10 with rope made from the same material according to standards generally accepted as ood. It is one feature that the invention permits .of rope being made with a relatively softer and therefore with greater strength, than heretofore; while maintaining in the strand a sufficient stability of form and a sufficient resistance .to surface abrasion. In this respect the invention 'both preventsba'clg'kinking, which is .particularly liable to o'ccur in aloosely laid rope, and provides greater strength per v rope. It has been. found in practice that such a rope has longer life, as compared with a 2 rope of equal diameter but of standard 'con- 'struction, and that'it retains greater strength than is customary with standard rope after any lmeasure of service which may have been adopted for comparison. Also, for reasons whichare incidental to its structure, the rope .of the invention is easier to splice, iseasier to handle when in service, and is subject to less liability of being damaged by unskillful handling as by being drawn from a coil inthe wrong wa' By its superior stability it enables'the ubricant within it,

the strengtli of fibre, and the other characteristics of the rope to perform their several functions to better advantage, thus insuring 40 that at any paricular instant arope thus constructed will be in better condition than a rope of" former standard construction would be, for whatever service may be demanded of.it'.-

.These objects are strands together with a relatively soft lay, ginmakin'g the rope, andarranging yarns m .a special manner in the strands, the yarns being made from hemp or other long fibre in. '60 the usual. way. The said arrangement is that some'of the yarns constitute a core and others of'them a cover for the core, with the yarns in the core laid in a different direction from the Iayof the yarns in the cover. Preferpoundof hemp in the.

attained by putting" the ably also the twist of the individual yarns in the cores is opposite to the twist of the individual yarns inv the covers. The pitch of yarns in core and in cover may be equal or diverse, but the difference in directionof lay prevents the outside yarns from ever being drawn into the valleys between yarns of the core when a finished rope is twisted reversely. As neither untwisting nor further twisting of. such a soft laid rope will seriously disturb the structure of any of the strands, the rope can easily resume its normal structural form after any such chance twisting. The individual twist of the yarns at the surface can be as hard as desired.

It is intended that. the patent shall cover, by suitable expressionin the appended claims, whatever features of patentable novelty exist in the invention disclosed.

In the drawing:

The figure is a side elevation of a rope embodying the invention with one end unlaid to indicate construction, and the relations of fibres and yarns within.

Referring to the drawings, the three strands 10 of the specimen rope chosen for illustration. are laid together by twisting them in ordinary manner, except that the lay is preferably soft, that is, with a pitch longer than What has-hitherto been considered normal or necessary for the particular size and kind of rope. Each strand 10 is homogenous, in that it is is composed wholly of long vegetable fibres, such as hemp. These fibres are grouped in yarns 14 which are individually twisted. As illustrated in the figurethe yarns in each strand are arranged in two groups, one of which,;12,'includ1ng 12', is twisted as a group in one direction, herein being called a core," while the other, 16, herein. called a cover, is laidin a sheath around the core 12 in a direction opposite to the twistof the core. Preferably the relative-pitch of these two twisted groups may be such that when the rope is stretched the fibres in each group will reach their breaking-tension" at about the same distance of stretch of the rope; as a whole. The -described construction provides a rope'which has in the interior of each strand a substantial body 12-of yarns with lay in the same direction as the lay of the strand in the rope; and has exteriorly in each strand av body of cover yarns whose lay everywhere.

crosses the lay ofthecor'e yarns and is oppo 1 site to the lay of the strands. -When the rope is put into use rand by tension is stretched, the tightening-of 'the cover yarns may compress. the core severely.. But the core affords a,fir1nresistance,being-ofthe same material as the cover werelaid' in the same direction as the cover, or as mighthappen if the core were made of the same material as the cover but with varns laid parallel and straight. In the last mentioned case the core yarns would become taut and would break before the cover yarns had reached their breaking stress producing a rope of weak ultimate strength. And in the case where all yarns in a strand are laid in a like direction, any untwisting of the rope such as sometimes arises in handling or in use, mightso. tighten the'twist of the cover yarns,

upontheir core, as to draw some or other of the outer yarns in between adjacent core yarns with Which-they are lying parallel.

This makes back-kinking which is a serlous evil because it spoils the rope, and which is always possible in ordinary'rope because when outer and inner yarns are laid in the same direction back twisting of thegrope as a rotation in the twist applied, The danger whole tightens the outer yarns more than, it does the inner yarns per degree of angular of such back-kinking is one reason Why the lay of ordinary rope is made so tight, and why it.cannot safely be made more soft as would be desirable in order to utilize a greater" proportion of the strength of the fibers. But in a'rope of the inventioneach strand has permanent stability of form notwithstanding severe nntwi'st lng ofthe rope,

,and notwithstandi-ng abnormal; twisting of r it, for no 'amount'of twisting or untwlsting the valley between two adjacent yarns-in the 1 can move any yarn in the cover of the strand so that it comes into parallelism with core thereof.- The cover yarns inevitably pass from crest to crest of the outer yarns 'of the core. However tight the coveryarns be drawn, by an untwisting of the rope, or however much they be relaxed by a twisting of the rope (which act holds the core yarns ,the more firmly in shape) they arein each ,case sustained on this interior support of rounded crests. Other advantages follow. Thus,'a surface of cleavage whereon slip can easily occur, and 'which may if desired be themselves in proper position. they can, if. desired, run with less pitch,-

- desirab specially ldhricated, is-provided in the midst of .each strand, and this makes-for flexibility of the completed rope. Inasmuch as the cover yarns are firmly binding the core yarns in their laid relations, the core y'arnsdo not have to be twistedso-tightly in order to hold Therefore more nearly longitudinally of the rope; or they may, as shown,.be ofa pitch approximating equality with the pitch of the cover yarns; or they may have greater pitch. .The yarns 14 are represented as being individually twisted-all in one direction in the core 12, and all in the other direction in thecover 16. The interior group of yarnsl2 in the coreis preferably twlsted with the case illustrated all of them together do not make as many yarns as are. in the cover. This, however, is a matter to be given congroup of core yarns surrounding it, as in the sideration when anyparticular'rope is de signed, and-if the interior body 12' were so large that the dangers indicated above were liable to arise, the remedy indicated. herein should be applied by reversing their direction of lay with respect to the outer yarns 12 of the core. In case of a strand having such a second reversal of direction of lay for its interior yarns, those yarns which constitute the outside layer of the core make a slip cover or sheath over the said reversed yarns within them, and a second surface of cleavage between yarns is thus provided, en

hancing flexibilityof rope and, as, above de scribed, further preventing any back kinking arising by-inter-engagement of interior yarns in case-the rope as a whole is untwisted In the making of the rope the yarns 14; are made according to ordinary methods of suchmatei'ial or mixture and of such size and degree of twist as may be considered e; and then for-the making ofthe core 12 a bundle of such yarns is twisted, so that its'yarns are, for example,-laid to the right, using machinery of any suitable type operating upon principles already known. Over thiscore the cover yarns are laid in the opposite direction. For ordinary purposesthis would complete a strand, 10.

The threeestrands 10,- or whatever other number of strands is to beused, may then be twisted together to make a rope-in the usual manner, preferably (laid at a pitch which is longer than .what is considered safe and necessary inrope made for the same duty but of the type at present standard in the rope industry.

This softness need -not result in dangerof greater surface abrasion, for the cover yarns may bemade' with individual twist hard enou' h to resist such. 5 v

Nor nee the softness of lay result in a slipping between fibres of the core and a disseminated throughout the whole body of.

the core, by a less intense constriction of the cover than if the fibres of the core lay all in parallelism with each other in one large mass. The force imparted at the surface of the core by the constriction of cover yarns 'upon it is transmitted throughout the core more readily in a case, as here, where a concentration of the core can occur by slight cross slip of yarn upon yarn, laterally, and then the frictional holding of fibre upon fibre, increased by this concentration, is aidthe local twist of the fibre in its own yarn, all tending to prevent the fibres from slipping longitudinally upon its adjacent fibres. Thus each fibre becomes capable of contributing to the rope whatever strength ,it has regardless of slip or weakness which may occur in ,some other part of the core. This point being safeguarded it follows from the greater length of pitch of strands (softness of lay) which thus becomes permissible that the resultant or average lines of all fibres and yarns become more nearly parallel to the axis than in the type of rope prevaili'ng hitherto. 'Therefore, when the rope of the invention is under. tension, the stress of fibres resultin from a given total tension is less than is t e stress of fibres in a rope of ordinary construction, wherein the angle of strands to the axis is greater. And this produces the consequence that the new rope as a whole in a given duty puts less 130135101131 'strees on its fibres, and is stronger, size for size, besides having greater flexibility, and being secure against kinking. By way of confirmation of this and as a further advantage, it has also been observed that experimental rope, embodying the invention and used for rtain work through a period equal to the life time of an ordinary rope in that service,

I claim as my invention:

1. A rope composed of a plurality of strands twisted together, each of said strands having a core of yarns of long vegetable fibres, said yarns bein twisted together, and a cover of yarns of laid around the core in direction opposite to the twist of the core.

2. A rope composed of a strands twisted together, each of said strands having a core of yarns twisted together and a cover of yarns twisted around the core in direction opposite to the twist of the core the said yarns in core and cover being sevplurality of s is at the end of the period still in good condition.

long vegetable fibres erally coinposed of long vegetable fibres twisted together to make the several yarns; the twist of individual yarns in the core being opposite in direction to the twist of individual yarns in the cover.

3. A ropefcomposed of a plurality of ELLIS w. BREWSTER.

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