US809386A - Rope. - Google Patents

Description

PATENTED JAN. 9, 1906.

E. D. METGALF.

ROPE

APPLICATION FILED OUT. 19.1905.

Witnaooeo .UNITEI) STATES PATENT OFFICE.

EDWIN D. METOALF, OF AUBURN, NEW YORK, ASSIGNOR TO COLUMBIAN ROPE COMPANY, OF AUBURN, NEW YORK, A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Jan. 9, 1906.

Application filed October 19, 1905. Serial No. 283,455.

To all whom it may concern:

' reference marked thereon.

This invention relates to improvements in fiber ropes, the invention being more especially, though not exclusively, applicable to cable-laid ropes.

The object of the invention is to provide a strong and durable rope of that type wherein strands of substantially equal cross-section are twisted about each other.

The invention willbe best understood from a description of a cable-laid rope as distinguished froma rope formed of successive cylindrical layers of yarns arranged in opposite spirals or so that the lay in the concentric layers is left and right handed alternately. A cable-laid rope is, as is Well understood by those skilled in the art, composed of three or more hawser-laid ropes twisted together. The hawser-laid ropes are each composed of three or more strands twisted together, and the strands are composed of an indefinite number of yarns twisted together. In forming the rope the fiber is usually twisted to the right to form the yarns. The yarns are twisted to the left to form the strands. The strands are twisted to the right to form the hawser-laid ropes, and the latter are twisted to the left to form the cable. Under strain the tendency is to untwist the cable-laid rope or, in other words, straighten the spirals formed by the hawser-laid ropes, this untwisting being resisted by the hawser-laid ropes,as any straightening of the spirals of the latter instantly results in the tightening of the twists of the same. The tightening of the twists of the hawser-laid rope does not tend to increase the twists of the strands, however, but, on the contrary, tends to untwist the individual strands.

Under such conditions if the strands, as isis that the yarns break sem'atvlm instead of each, both inside and outside yarns, carrying its own proportion of the load. This will be clear when it is remembered that the yarns forming a strand such as described are all given the same number of turns or twists in a given length of the strand, and consequently the outside yarns, as they extend through the longer path, are necessarily considerably longer than the inside yarns, and any untwisting relieves the tension on the outer yarns Without relieving proportionately the tension on the inside yarns. To overcome this defect, the yarns of the strands are in accordance with my present invention arranged in concentric layers all twisted in the same direction in the strand, but with this difference, that in a given length of strand the inner yarns are given a greater number of twists than the outer yarns.

In the practical embodiment of the invention the inner yarns take the form of acore, each yarn being as near as may be equidistant from the center, and the outer yarns take the form of a sheath, each yarn also being as near as may be equidistant from the center. The core is first twisted and the sheath and core then twisted together, the direction of twist being the same in both the core and sheath; but the number of turns in the core is greater than the number of turns in the sheath. For illustration the proportions may be approximately one and one-half turns or more in the'core to one turn in the sheath in a strand for a one-and-one-fourth-inch cable-laid rope. With this formation of strand while the yarns of the core and sheath are not of the same length, yet the range of elasticity of the yarns in both is approximately equal, and untwisting of the strand acts to proportionately re-v lieve both the inside and outside yarns, so that each at all times bears its due proportion of the strain, and the breaking strength of the rope will therefore more closely approximate the sum of the strength of the individual yarns.

In order that the invention may be more clearly understood, reference is made to the accompanying drawings, in-which Figure 1 is a View of a short section of cable-laid rope with one end opened out to show the component parts. Fig. 2 is a detail elevation of one of the strands, the outer layer or sheath being shown in dotted lines.

In the drawings like letters of reference in dicate the same parts.

The body of the cable-laid ropeis indicated at A, the three hawser-laid ropes at B, the strands of the hawser-laid ropes at C, the'yarns of the sheath or outer part of the strands at I), and the yarns of the core at E.

The whole body of the finished strands 0., the core and sheath-it will be noted, is twisted in the same direction; but the core is given a greater number of turns for a given length. Thus while the action of each strand as a whole or unit in the rope is the same in so far as maintaining the form of the rope is concerned, yet strain is distributed evenly to all of the yarns in the strand, the yarns will yield and stretch to a uniform degree before rupture, and the effect of untwisting does not, as heretofore, throw the entire strain on the internal yarns of the strand.

The strands formed as described are twisted reversely into the hawser-laid ropes B, and the latter are in turn twisted reversely of their own twists into the cable-laid rope A.

The number of turns in the sheath of the strands in the hawser-laid ropes and cable-laid rope may and preferably do conform to ropes of this type as now manufactured; but the cores of the strands are given a greater number of turns than the strands, as will be readily understood from the foregoing specification.

What I claim is 1. A rope consisting of strands each twisted about the other and each strand formed of yarns arranged in a core and a sheath therefor, both twisted in the same direction and the core being twisted a greater number of turns than the sheath in a given length of the strand.

2. A cable-laid rope embodying strands, each composed of a core and asheath formed of yarns, and both core and sheath twisted in the same direction, the core having a greater number of turns than the sheath in an equal length of rope.

3. A rope composed of twisted yarns, the yarns being arranged in cores, and a sheath surrounding each core, said cores and sheaths all being twisted in the same direction but with a greater number of turns in the cores than in the sheaths. to form strands, said strands being twisted about each other and in direction opposite the twists of the strands to form hawser-laid ropes and said ropes being twisted about each other in direction opposite the twists in the hawser-laid ropes to form a cable-laid rope.

4:. The process of making rope strands which consists in twisting a bundle of yarns to form a core then applying a sheath of yarns to the twisted core and twisting said core and sheath in the same direction, whereby the twists in the core and sheath will be in the same direction but with agreater number of turns in the core.

EDWIN D. METOALF.

WVitnesses:

HAROLD Gr. Mn'roALr, SMITH B. KIMBALL.

Images