US3691751A

US3691751A - Interlocked type wire strand

Info

Publication number: US3691751A
Application number: US136687A
Authority: US
Inventors: Carl Duane Hiller; Harold W Karge
Original assignee: Bethlehem Steel Corp
Current assignee: WILLIAMSPORT WIREROPE WORKS Inc A CORP OF PA
Priority date: 1971-04-23
Filing date: 1971-04-23
Publication date: 1972-09-19
Anticipated expiration: 1989-09-19

Abstract

A lock type wire strand for aerial tramways and the like has the bottom portions of the interlocked outer wires prolated, or bulged. The prolated portions of the interlocked wires extend into the interstices between wires in the next adjacent layer of wires under the interlocked layer of wires and contacts adjacent wires in said next adjacent layer to provide additional resistance against compression forces and relieve secondary bending strains in the interlocked wires of the strand.

Description

United States Patent Hiller et al. [451 Sept. 19, 1972 [54] INTERLOCKED TYPE WIRE STRAND 2,106,060 l/l938 Ostrander "57/145 X [72 Invemo C D 2,385,24l 9/l945 White.. ..57/l45 1 rs :1 w 22 i" 3,188,791 6/1965, Grimes et al ..57/l6l x both of 3,425,207 2/1969 Campbell ..57/ I45 [73] Assignee: Bethlehem Steel Corporation Primary Examiner-Donald E. Watkins [22] April 23, 1971 Attorney-Joseph J. O Keefe [2]] Appl. No.: 136,687 [57] ABSTRACT I r p A lock type wire strand for aerial tramways and the [52] us. Cl. ..57/145 like has the bottom p i of the interlocked oute s1 rm. Cl. ..D07b 1/06, D07b 1/08 wires prelated. or s The Prelared Portions of the [58] Field of Sear h 57/144, 145 4 1 1 1 3 interlocked wires extend into the interstices between 57 9, 15 39 wires in the next adjacent layer of wires under the interlocked layer of wires and contacts adjacent wires in 5 References Cited said next adjacent layer to provide additional resistance against compression forces and relieve secon- UNITED STATES PATENTS dary bending strains in the interlocked wires of the 338,9l3 Batchelor ..57/l46 Smmd' f 1,818,845 Fess] ..57/l6l X 12 Claims, 7 Drawing Figures Murmur 19 m2 INVENTORS Carl Duane ///'//er Hora/0 144 Aorye BY ATTORNEY INTERLOCKED TYPE WIRE STRAND BACKGROUND OF THE INVENTION The present invention relates to lock type wire strands and more particularly to lock type strands which are particularly resistant to fatigue failures due to transverse loadings.

lnterlocked outer wires are frequently used on wire strands which are to be subjected to transverse compressional forces such as may result from the passage of tramway wheels or the like over the strand. The interlocked sections give the strand a smoother outer surface and extended wear resistance and also provides additional bearing strength'over that which is available with the use of round wires. The two most common types of interlocked strand are so-called half-lock, or O-H lock, and full-lock, or Z-lock strand. Full, or Z- lock, strand consists or one or more outer layers of interlocked Z-shaped wires. Half-locked strand is comprised of alternating H, or rail, shaped wires and substantially round wires. The round wires are interposed between the extensions on the H, or rail shaped wires.

Customarily, the interlocked wires of a fully locked strand are superimposed or supported upon a subjacent layer of half locked wires to provide a more even supporting surface for the Z-shaped wires. The half-lock layer of wires is then supported in turn upon a layer of conventional round wires. An example of this preferred construction is shown in US. Pat. No. 2,385,241 to White. Frequently, however, the full-lock layer of wires may be superimposed directly over a layer of round wires. As shown in the White patent, there may also be several superimposed layers of full-lock or half-lock wires or both in one strand. In any of these constructions, however, an interlocked layer of wires of some nature is finally superimposed upon a layer of round wires. When a transverse compressional load is applied to the strand, such as may occur when a tramway wheel passes over the strand, the momentarily high compression loading may cause such high secondary stresses and strains in the outer portions of the strand as to cause breakage of the interlocked wires even though their tensile strength is not exceeded, or even approached. This problem of breakage has been found to be particularly troublesome in a layer of interlocked wires which directly overlies a subjacent layer of round wires, and is particularly acute when the layer of interlocked wires overlying a layer of round wires happens to be a layer at or near the surface of the strand.

Since a layer of interlocked wires directly supported upon a layer of round wires is usually a half-locked layer, the problem of breakage more often occurs in half-lockedstrand. Full-locked strand, however, can also frequently suffer such wire breakage. The reasons for these breakages appears to be that the heavy transverse compressional loads placed upon the strand by tram car wheel loadings and the like subject the outer wires of the strand to secondary bending stresses which are above the fatigue endurance limit of the individual wires. Many tramway tracks strands consequently develop numerous wire breakages at a very early date relative to the actual wear of the strand and its normally expected life. Such premature breakages of the wires may cause sudden and disastrous failure of the entire strand if the wire breakages are not promptly detected. It is frequently difficult to detect breakage of an individual interlocked wire, however, because the wire will be locked in the strand rather than protruding from the strand as will usually occur in a normal rope or strand in which broken outer wires occur, and it is uneconomic in any event to have to replace an entire strand when only the outer wires are damaged.

SUMMARY OF THE INVENTION The foregoing difficulties of prior lock-wire strands subject to transverse loading have been successfully obviated according to the present invention by stranding the interlocked layer of wires and the immediately subjacent layer of round wires in the lock-strand with the same lay length and direction and providing a prolated profile to the bottom of at least some of the interlocked wires. The prolated sections of the interlocked wires are oriented so they extend into the interstices between adjacent wires of the subjacent layer to provide support against transverse loading of the interlocked wires.

The arrangement of the invention substantially eliminates premature breakage of the interlocked wires of the strand due to transverse loading of the strand since the prolated lock wires are. supported not only by the contiguous lock wires on either side but are also provided with contiguous support by the underlying layer of wires. Secondary bending stresses are thus so far eliminated that what little bending stress remains does not begin to approach the fatigue endurance limits of the individual lock wires of the strand. Premature breakage of the outer wires of the stand is thus largely eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a portion of a half-lock wire strand according to the invention partially cut away to reveal the lay of the wires.

FIG. 2 is a cross section of FIG. 1 at 2-2.

FIG. 3 is an enlargement of a portion of FIG. 2 to better show the prolate profile of the interlocked wires.

FIG. 4 is a portion of a full-lock wire strand according to the invention partially cut away to reveal the lay of the wires.

FIG. 5 is a cross section of FIG. 4 at 5-5.

FIG. 6 is an enlargement of a section of FIG. 5 to better show the prolate profile of the interlocked wires.

FIG. 7 is a cross section of a wire strand according to the invention in which a full-lock layer of wires is supported-upon a half-lock layer of wires having the prolate profile of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1, 2 and 3 there is shown a half-lock wire strand 11 comprised of a center wire 13, four wires 15 laid about the center wire 13 in a right hand layer, or operation, l6, 10 wires 17 laid about the wires 15 in a left hand operation 18 and an outer layer 19 of 20 wires laid in a left hand operation about the wires 17 with the same angle of lay as the wires 17. There are two types of wires in the layer 19 which comprises a so-called half-lock or 0-H type interlocked layer. Layer 19 is comprised of round wires 21 alternating with H, or rail, shaped wires 23 which extend partially about the circumference of the round wires 21 so that the entire layer of wires is gripped or locked together into a unitary layer. The bottom of each rail section 23 is prolated as shown at 25 so that it extends down partially into an interstice between two adjacent wires 17 of the subjacent layer of wires 18 and is partially supported against two contiguous wires 17 of the layer of wires 18. The alternating round wires 21 on each side of the rail sections 23 are meanwhile supported directly upon the underlying wires 17. The rail sections 23, therefore, which constitute, because of their shape, a major proportion of the surface contact area of the strand, are supported against transverse compression forces by their gripping action on adjacent round wires 21 of the interlocked layer 19 and also by direct contact through their prolate bottom sections with two contiguous wires 17 of the subjacent layer of wires 18. EAch rail section 23, therefore, because it is nested within a pocket between four adjacent wires is so supported that it suffers substantially no secondary bending stress when subjected .to transverse compression forces and the fatigue limit of the rail sections 23 is thus not exceeded before the remainder of the strand is subjected to substantial wear. 1

While the support of the rail sections 23 is particularly'important when the layer of half-lock wires is the surface layer of the strand, it will be understood that the half-lock layer might itself constitute an underlying operation or layer of the strand.

in FIGS. 4, and 6 there is shown a full-lock, or Z- lock, strand 31 having a central wire 33 surrounded by a layer 34 comprised of six round wires 35 having a right hand'lay, a layer, or operation, 36 of 12 wires 37 laid about the wires 35 with a left hand lay, and 24 Z- profile wires 39 laid about the wires 37 with a left hand lay and the same lay angle as the wires 37 to form a fully locked layer of wires 41. The bottom section of every other Z-profile wire 39 is bulged, extended or prolated as shown at 43 so that it extends into the interstice between two adjacent wires 37 of the subjacent layer, or operation, of wires 36 and is supported by two contiguous. wires 37 in this layer. If desired the Z- profile wires 39a between the prolated wires 39 may have a slight depression 45 formed as shown on their undersides which seats partially over the immediately underlying wire in the subjacent layer of wires 37.

It will be seen that due to the prolated bottom portionof every other 'Z-profile wire 39, that each

wire

39 and 39a of the full locked section or layer 41 is thoroughly supported against transverse compressional forces.

It may be desirable in some cases rather than using a prolated Z-profile wire as explained supra, to use a preferred prolated half-lock layer under the outside full-locked layer of wires as illustrated in cross section in FIG. 7. As shown in FIG. 7, a regular Z-profile layer 50 of wires 51 is directly supported upon the relatively even surface of a subjacent layer 52 of half-locked

wires

53 and 55. The bottoms of the rail section wires 55 of layer 52 are prolated according to the present invention for complete support against any transverse compression forces such as may arise from tramway car loadings or the like. Since the half-lock layer, or operation, 52 of

wires

53 and 55 is completely supported against transverse loads, it will be seen that the superimposed layer or operation 50 of full-lock wires 51 is also completely supported against transverse compression loads. I

In the construction shown in FIG. 7 every wire 51 overlying a prolated'wire 55 in the half-lock operation of wires 52will have a conventional flat bottom profile, while every other wire 52a overlying a round wire in a half-lock layer 52 will preferably, as shown, have a slightly concave bottom profile to provide additional bearing surface area between the Z-profile wire 51a and the subjacent round wire 53. In this case, of course, the two operations of interlocked

wires

51 and 52 will have the same direction and angle, or length, of lay. If

I the two operations of interlocked wires are not, as may portions of the prolated wires 55 of the subjacent-halflock layer 52.

While the prolated sections of the various interlocked wires according to the invention are shown as rounded extensions on the normally flattened under portions of the interlocked wires, the prolated sections may actually take different shapes so longas they are extended between and into contact with adjacent wires of a subjacent layer of supporting wires. The profile of the prolated sections might, for instance, be angular or even depressed on the portions which contact the adjacent wires. It will ordinarily be found more convenient, however, to make the profile substantially evenly rounded as shown as this contour is more easily attained in a conventional wire drawing operation such as is usually used to shape the constituent interlock wires. A fairly evenly rounded profile may also be beneficial in an interlocked strand which is to be subjected to bending or the like.

It will also be recognized that the conventionally round wires of the subjacent supporting layers may have more or less conventional cross sections other than round such as oval, ovoid such as, for example, egg shaped or the like, or may even almost approach a rectangular shape. The shape of the underlying wires is not significant so far as the invention is concerned so long as there are interstices between the underlying wires for the prolated portions of the overlying wires to extend into a secure support for the superimposed interlocked wires.

We claim:

1. A wire strand comprising:

a. a first interlocked layer of wires having prolated lower profiles on at least some of the constituent wires,

b. a second subjacent layer of wires immediately under said interlocked layer of wires having the same lay angle and direction of lay as said interlocked layer of wires,

0. the prolated sections of said first layer of wires extending into the interstices between wires of said second subjacent layer and being in substantial contact with adjacent wires of said second layer.

2. A wire strand according to claim 1 wherein said wires of said second layer have cross-sectional profiles selected from the group consisting of substantially round, oval and ovoid profiles.

3. A wire strand according to claim 1 wherein said first interlocked layer of wires is comprised of halflocked wires.

4. A wire strand according to claim 3 wherein each rail section of said half-locked wires has a prolated bottom portion.

5. A wire strand according to claim 4 wherein said half-locked layer of wires is the outermost layer of wires in said strand.

6. A wire strand according to claim 4 wherein said half-locked layer of wires is overlain by a full-lock layer of wires.

7. A wire strand according to claim 6 wherein said half-locked layer of wires and fully locked layer of wires have same direction and angle of lay and the bottoms of the alternate wires of said fully locked layer overlying subjacent round wires of said half-locked layer of wires have slightly concave profiles providing v substantially greater than line contact between the said fully locked wires and the said round wires of said halflocked layer of wires.

8. A wire strand according to claim 7 wherein said fully locked layer of wires is the outermost layer of wires in said strand.

9. A wire strand according to claim 1 wherein said first interlocked layer of wires is comprised of fully locked wires.

10. A wire strand according to claim 9 wherein at least every alternate wire of said first fully locked layer of wires has a prolated lower profile.

l l. A wire strand according to claim 10 wherein said first fully locked layer of wires is the outermost layer of wires in said strand.

12. A wire strand according to claim 11 wherein the fully locked wires which are not prolated have depressed lower portions contacting underlying wires.

I! III i i

Claims

1. A wire strand comprising: a. a first interlocked layer of wires having prolated lower profiles on at least some of the constituent wires, b. a second subjacent layer of wires immediately under said interlocked layer of wires having the same lay angle and direction of lay as said interlocked layer of wires, c. the prolated sections of said first layer of wires extending into the interstices between wires of said second subjacent layer and being in substantial contact with adjacent wires of said second layer.

3. A wire strand according to claim 1 wherein said first interlocked layer of wires is comprised of half-locked wires.

7. A wire strand according to claim 6 wherein said half-locked layer of wires and fully locked layer of wires have same direction and angle of lay and the bottoms of the alternate wires of said fully locked layer overlying subjacent round wires of said half-locked layer of wires have slightly concave profiles providing substantially greater than line contact between the said fully locked wires and the said round wires of said half-locked layer of wires.

11. A wire strand according to claim 10 wherein said first fully locked layer of wires is the outermost layer of wires in said strand.