[1]Patented Dec. 3, 1935 UNITED STATES -PATENT OFFICE 2,022,683 ROPE Charles MacKinnon and Ellis W. Brewster, Plymouth, mass., assignors to Plymouth Cordage Company, North Plymouth, Mass., a corporaUon ofMas&uhusetts Application October 10, 1932, Serial N6. 637,008 8 Claims. (Cl. .117-2) This invention relates to improvements in rope. More particularly it relates to rope twisted of vegetable fibre, whether single strand, or formed of a plurality of strands. Thus the invention may be considered as applicable to rope in general except wire rope. And while its greatest utility may probably be found in ropes made of long and hard fibres, such as manila and sisal, utility will be found also in rope made of the lo -horter and softer fibres. It is a result of the invention that the making of rope with a softer lay of the strands becomes practicable, without danger of the aris'mg of internal back kinks. In ropes of ordinary construction such kinks may occur when the rope is back-twisted, or is so handled that some of the yarns become tighter than normal and work into the midst of others, as by iriner yarns being bulged into the outer. In such cases.a restora20 tion of the normal rope structure is difficult, or even impossible. The consequencies are sometimes serious. It is not merely that the work in which the rope is engaged must be suspended, for 6orrection or replacement of rope; but the 25 kinking is destructive of the rope; and the failure may occur at a moment when failure or unavailability of therope is disastrous to surroundings. The danger is present in all rope of ordinary construction, according to prevalent stand30 ards, particularly in those types of rope which are made soft for easy handling. Among large rope3 back kinking is perhaps the most frequent cause of premature destruction of the rope. - It may result, for example, from wrong judgment, 35 ignorance or carelessness in the repeated coiling of a rope; and it may occur in a free rope as well as in a rope which is in capstan, or other severe use. As compared with ropes hitherto known, the .4o rope provided by the invention is consider-ably more stable and resistant to distortion- In consequence it can safely be made with a relatively loose and long lay. With the long la and I y stability come considerable, improvements in 45 st.rength, in general utility -and in durability. There may pLIso be increase of flexibility, as compared with rope made from the very same stock accordance to standards which h.eretofore have been generally accepted as good. Strength re50 sults because a pull on rope which has a longer I-ay produces less of a shearing stress on the fibres, since their angle to the direction of pWI is less. This angular improvement contributes also to durability, because the friction of fibre 5r) across fibre becomes I ' ess, during that slipping which occurs as the rope when in use becomes repeatedly bent and straightened, or stretched tight and relaxed. ent yarns are niaintained -against disarrangement, and especially the disarrangement known a3 "back-kinlsing", in handling, use or abuse of the rope. The element by whose introduct' I ion into the strand this is accomplished; has no 6 fundtion of contributing directly to the tensile strength of the rope. Its structure and ftmetion are those of a septum, a means for positively holding the yarns of adjoining groups against mutual disarrangement. Specifically, it hinders. 10 the yarns of one course, when tightened by a back twisting of the rope as a whole, from ixitruding theniselves between yarns of an adjoining course, by force of that same back twisting. A further feature of the invention resides in 15 the fact that paid introduced means may carry a suitable substance absorbed or adsorbed within it, liquid, plastic, or colloidal, which may 9,.rve any of.several functions, for contributing to the flexibility of the rope, and for prolonging 'ts 20 useful life. Thus, it may hold material which constitutes a lasting source of lubricaxit, for gradual distribution among the yarns;. or which provides lubricated slip surfaces between inner, and outer courses @ of yarns, over wliich surfaces 25 said yarns readily may slip dur'mg flexing of the rope; or it may be a substance which prevents or delays the entrance of water, or of other deleterious liquid or fume@. Still another feature, which is an incident of 30 the soft lay of the elements togetlier, is that the improved rope may'be easily spliced. Thus, in general, the invention provides for the making of rope which has greater strength per pound of its 'own weight than a rope of similar 35 dimension and stock, made according to hitherto customary specifications; has greater stability; and may be s6 designed as to have increased and easy flexibility; all without danger of back kinking. These improvements tend to increase its 40 utility; to prolong its u eful life; to facilitate its handling; and, in the operation of the rope, to reduce the power required and to iiierease the efficiency of the rope as an instrument transmitting power. 45 The invention attains these results by introducing a septum between groups of yarns or flbres which are adjoining each other in a rope strand. In most cases these will be groups which adjoin in interior and exterior relation. The septum r)O may beformed of strips of a suitable material, wrapped helically or otherwise around the one group and separating that from the adjoining group. Th., material may be various, as paper, cloth, rubber, etc., strips, which are materials'55 in sbeet form, simple or composite, or even may 'be a winding of suitabISr strong twine, thread or fibre. The wrapping of the strips may be exeIt is therefore one object of the invention to cuted with successive convolutions i3verlapping, GQ provide a strand structure wherein the constitumaking a closed sheatli; or the convolutions may 60
[2]have open spaces betweeti them, as desired, and the pitch thereof may be greater or less than the pitch of the yarns. Also the strips may he wrapped in the direction of twist of the strand, or couhter thereto, or may be merely folded about the groups which they enclose. Or in some cases the septum may be a strip which is fed in with the yarns, into the strand forming tube, and is thereby folded, laterally and without individual 10 twist, around the body of fibres or yams with which it is to be associated. The septum when arranged between exterior and interior groups@ for example, maintains a barrier which ptevents the yarns of the interior 15 group, next inside the septum, from bulging out into the exterior group, between yarns thereof, when the rope is back twisted; and on other occasions it would constitute a barrier support at the surface of the interior group, effective to pre20 vent tightened exterior yarns from sinking between loosened iiiterior yarns if the eiterior should ever become constricted thereon at a time when those inner yarns were loose. As a result the yarns, botl@ exterior and inte25 rior in a strand, may be assembled togetb.er with a much softer and straighter lay than has been usefully practicable heretofore; and the greater strength and other said benefits are attained with safeguard against"back-kinking". 30 It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty exist in the invention disclosed. In the accompanying &awing, which is a 35 schematic representation of different embodiments of the invention, Figure 1 shows a piece of three strand rope embodying features of the invention, with end portiojas of two strands unlaid; 40 Figures 2, 3 and 4 are cross sections through strands of other ropes in which;-in Figure 2, the septum is arranged around a group of' center yarns to separate them from their cover yarns, but is laid straight along the axis and is wrapped 45 by being folded around the center group; in Flgure 3 the septum is between adjoining groups of interior yarns, as well as around them; and in Mgure 4 the interior tensile elements are unspun fibres whose groups are separated by septa 50 that lie between these groups but do not surround them; and Mgure 5 shows material that may be used for the septum, being tw . o plies of paper with uns,@pun fibre between them. 55 Referring to the drawing, it will be understood that the pitch at which the strands IC of a rope are laidl,,,or the core yarns 12 of each strand, or the intermediate yams 14 or the exterior yarns 60 16 thereof, is a matter- whieh is determined by the rope maker, and that it may vary@ over a wide range, according to the desired duty of the rope and the judgment of the maker. The drawing therefore, in these respects, is merely 65 conventional to represent a rope structure. When the invention is to be embociied in a rope, the rope may safely be designed with its angle of lay more nearly parallel to the axis, due regard being had to the expected duty of the rope, 70 than would be good practice if the rope were to be of the style hitherto customary. This lesr, angle and greater parallelism produce what is herein called a longer or softe'r lay. This statemerit applies to all elements of the rope. It is 76 especially useful when a high degree of flexibility of the core is desired, that the lay may be made particularly long. 'Each strand 10 comprises whatever kind of stock is customary or desired, herein maumed to be manilla or other long and strong vegetable 5 flbre stock; and each mgy embody a multiplicity, of spun flbre yarns 12, 14, 16, which themselves are grouped and twisted together into the strand form, according to any choice among the many desirable relations. 10 The invention, however, in the form illustrated in Pligure 1, makes a distinction between interior and exterior layers of the yarns; and introduces septa i3, 15, which segregate the yams of each group. 15 The septum may be In the form of stril)s of tough flexible sheet material, as paper, cloth, rubber or other, but it is believed that some variety i)f tough flexible organic material wiU ordinarily be found best, wound around the interior group 20 of yarns. The winding may be either with an overlapping of successive convolutions of the strips (as at th6 extreme left of Mgure.1) or without such (as gt the extreme right); or even'there may be open spaces .(not illustrated) between the -@3 convolutions. The strips 13, 1 5 may be laid with pitch equal to or greater than the pitch with which the yarns are laid in their strand, or with a shorter pitch as illustrated, in which latter case a greater binding effect is attained. ALso 3o the shorter piite,,h of the strips approximates more nearly a 90' ctossing betweeri strips and yarns, and produces a firm support for the exterior yams 14 or 16 which are laid directly upon the wrapping. 35 The strips 13, 15 may be wrapped with direetion of lay opposite to the direction of lay of their en@wrapped yams, if desired. Also, the exterior groiip of yarns may be laid in direction opposite to the direction of lay of the interior 40 yarns,, if that be preferred. The segregation of yarns in groups within a strand, and the provision of a septum or wrapping; for the Interior group 12 or 14, which septuxn underlies the exterior group 14 or i 6 in a finished 45 strand, is particularly important in that it permits of the yams of each gr6up being assembled with a soft lay. The rope stabilizer, which is the septum or wrapping 13, 15, provides means for preventing subsequent intrusion of yarns of one groUP 50 into the other. The stabilizer is a barrier which exercism its most important function whenever the rope exPeriexices distortional stresses which tend, to thrust yarns of one group into the midst of yarns 55 of the other group. It will be understood that in an ordinary threestrand rope, for example, each strand is composed of spun yarns; or sometimes may contain a body of flbres which are laid in *ithout be- oo ing spun, or being only slightiy twisted. D31tiaUy, this group of yarns and/or fibres was twisted in one direction, right Qr left, to make a strand; and then three of these strands were laid together and twisted in the opposite direction to make the rope. 65 After it is in use, such a rope may happen to experience aback twisting force, in the course of being handled in either of several, ordinary ways; and when this occurs to the rope as a whole, the untwisting of the rope produces a bulging of the 70 strands, and in each strand makes a complex distortion and displacement of the mutuill relation of the component Zxa-rns. By the invention the yarns are held in their original group formation, and are held against 75
[3]the tendency toward extrusion of local nubs or kinks. The sheet material 14, bridging adjacent yaxns, affords a barrier to the ext-rusive force by which Interior yarns would tend to thrust apart their adjacent exterior yarns. It prevents deep or permanent penetration of the outer yarns by kink or.nubs of the inner. The introductipn of the septum makes the particular rope somewhat stiffer than it would have 10 been without the septum; biit the presence of the septum makes it possible to design a rope so that even when thus somewhat stiffened it Is more flexi ' ble than would be practicable for, a rope of the same order without the septum. 15 The material of this septum 13, 15, if suitably laden with oil or grease, may serve also as a lubricating agent, and can hold the,grease for gradual distn'bution through the strand. Whether or not it thus distributes lubrication, the slip 2o surface, which the septum presents between interior and,exterior groups of yarns, help@ the respective groups of yarns to execute that slipping tvhich occurs when a rope b,-nds around a pulley, and when a rope is subjected to tensile stress, 25 because it mak?s less friction and less fibrebreaking stress. For the holding of a lubricating compound as a source of distribution to yarns during life of the rop.e, a sheet-material baving absorbing power 3o may be employed, as felt; for affording an easy slip surface, a tough paper with calendered surface. If the core yarns have extra lubricant, and this paper wrapping be laid with its own convolutions not mutually overlapping, then the in35 terior yarns can serve as somewhat of a reservoir for lubri@ant that will eventually work its way to the exterior yams. Cellophane may be regarded as a variety of paper, and this special characteristic Is noted, that whereas ordinary pa40 per lias a surface of distinguishable, fibres, cellophane or hke material has a smooth continuous surface, and the abrasive effect'of yarns slipping over its surface wiD be le'ss, and the lif6 of the septum will not so soon be affected by abrasion. 45 Mgure 5 represents a composite septum, having two strips 15a, 15b of flexible sheet material, which may be of any of the.niaterials mentioned. in connection with the septa 13, i 5. These strips are stuck together by a suitable water-proof ad5o hesive substance, such as asphalt, embedded In which is a series of longitudinally disposed filaments 15c @vhich, preferably, are unspun fibres of vegetable origin, as hemp or- sisal, forexample, extending side by side in approximate parallelism. 55 The flbres may be introduced by laying them on one of the strips 15a, 15b, duting the operation of puttin.- the strips together, which preliminaruy will have been coated on one face with the adhesive; and by pressure these fibres become firmly ,.co secured in the two-ply structure. Such a septum, having superior qualities of strength, durability and tenacity, may be employed in place of the single-ply and unreenforeed. septa previously dezcribed. 65 It is preferable that the septum surface presented to the yarns be a c6ntinuous sheath, but owing to difference of pitch a septum made of discontinuous small barriers may provide the desired protection especially if wrapped at a pitch . 70. diverse from those of the tensile yam-groups which are to be kept separated. As the septum is not one of the.tensile elements of the rope, being merely a partition among such, the flat helical s.trips of paper niight continue to serve as septa, 75 even ff they should become rent by extreme bending of the'rope, because the resulting fragmentary, discontinuous, sheets would still remain in place, being inescapably enclosed. Moreover, the paper may be on one side adhesive. For waterproofing a rubber treatment may be employed, 5 vulcanized or not as may be suitable. Constructions emb(>dying the invention are not limited to single ply of paper, and, if there be more than one ply any us-,ful material may be incorporated between them. Io More than one ply may be desirable when the rope Is large or the number of center yarns very large, or the core made of a single large body of unspun fibres, which last, so far as the claims herein are concerned, is to be regarded as the 15 equivalent of a body of spun yams. Figure 4 illustrates a. strand having a core of a larger body of unspun fibres; and Mgure 3 a core of a large body of yarns. Through the midst of this body, in each instance, are septa which pre- 20 vent disarrangement of fibres or yarns from one part of the core into another. These are shown in order to indicate thai the septa are not necessarily laid helically, and that th@y may sub-divide a body. In Mgure 3 the body of yarns is in,quad25 rants 14", and a septum 15" covers three sides of each quadrant, two radial and one peripheral. Each strip 15" may be applied to its own group of yarns.before the groups are assembled, either being wrapped helically, or being laid parallel to 30 the axis and formed about its quadrant by a special die or by the general die which forms this part of the rope. If having adhesive surface, these septa may adher-e to each other after being assembled. 35 In Flgure 4 the septa 15... are for each of two opposite quadrants, and each is V-shaped, thus holding the bodies of unspun fibres 14... in order among themselves but not circumscribing them. In Pigure 2 a large core of spun yams 14', 4U within outer yarns 16', is shown surrounded by a s eptum 15' which is laid parallel to the axis and is formed around the core 14' by mere bending; a nd to indicate this in the drawing the edges are r epresented as being not quite closed together. @45 However, considering the extent of bending w hich most ropes must undergo, the helical lay of s eptum indicated In Flgure I will probably be fo und better for most putposes. And for a Simll ar reason the use of flnely wrinkled stock, as 5 0 c repe, will faeflitate a bending of the rope with le ss fracture of the septum. If a metal strip be employed for the septum it s hould be laid so loosely that it will not interfere w ith the proper functioning of the tensile ele5 5 m ents of the rope, which, being of fibre, are aubje ct to considerable variation of dim6nsion -bet ween stress and. slack conditions, and dry and h umid conditions. Such a metal strip may be u sed if it be sufriciently :Oexible and sufficiently 6 0 lo ose in dimension to accommodate itself to these c onditions. It wiU be understood that in the cordage Industr y strands such as are heie represented as belng compounded with other strands, to miake a plural 65 strand rope,. are well known to be each capable of use as a rope by itself; so that the terms "strand" and "rope" are more or less interchangeable. The
