Wire-Rope-User-s-Manual-AIS.pdf

8/13/2019 Wire-Rope-User-s-Manual-AIS.pdf

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WIRE ROPEUS RS M NU L

OMMITTEE WIRE ROPEPRODU ERSmerican Iron and Steel Institute


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This publication is a joint effort o f t he .COMMITTEE OF WIRE ROPE PRODUCERS/American Iron and Steel Institutea nd theW I RE R O PE TECHNICAL BOARD

The Wire Rope Technical Board WRTB) is an association of engineersrepresenting companies that account for more than 9 percent of wire ropeproduced in the United States; it has the following objectives: To promote development of engineering and scientific knowledge relating towire rope; To assist in establishing technological standards for military, governmental an dindustrial use; To promote development, acceptance and implementation of safety standards; To help extend the uses of wire rope by disseminating technical and engineering

information to equipment manufacturers; and To conduct and/,or underwrite research for th e benefit of both industry an duser.

Data, specifications, architectural/engineering information and drawings presentep inthis publication have been delineated in accordance with recognized professionalprinciples and practices, and are for general information only. Suggested proceduresand products should not, therefore, be used without first securing competent advice withrespect to their suitability for any given application.The publication of the material contained herein is not intended'as a warranty on thepart of American Iron and Steel Institute-or that of any person named herein-thatthese data are suitable for any general or particular use, or of freedom from infringementof any patent or patents. Any use of these data or suggested practices can only bemade with the understanding that American Iron and Steel Institute makes no warrantyof any kind respecting such use and the user assumes all liability arising therefrom.COMMITTEEOF WIRE ROPE PRODUCERSAmerican Iron and Steel Institute1 16th Sfreet,N.W.Wasl1 ngt9n, D.C. 2 36Copyright 9 9 by American Iron and Steel InstituteAll rights reservedPrinted in U.S.A.Permission to reproduce or quote any portion of this book as editorialreference is hereby granted hen making such reproductions or quotationsthe courtesy of crediting this publication andmericanIron andSteelInstitute will be appreciated


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23.4

5

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APPENDIX AAPPENDIXBAPPENDIX CAPPENDIXDAPPENDIXEAPPENDIX F

CONTENTSINTRODUCTION / 5BASIC COMPONENTS / 7WIRE ROPE IDENTIFICATIONAND CONSTRUCTION / 9HA NDLINGWIREROPE /17Receiving, Inspection and Storage /1 7Wire Rope Installation / 18Unreeling Uncoiling / 19Seizing Wire Rope / 22Cutting Wire Rope / 24End Attachments / 25Efficiency ofEnd Attachments /2 5Socketing/ 28Wire Rope Clips / 29How to Apply Clips / 29Wedge Sockets / 33Drums-Grooved / 34Drums-Plain Smooth) / 35Drums-Multiple Layers / 36OPERAnON AND MAINTENANCE OF WIRE ROPE / 37Sheaves Drums / 37Bending Rope Over Sheaves Drums / 39Inspection of Sheaves and Drums / 42The X-Chart -Abrasion Resistance vs. Bending-Fatigue Resistance / 44Breaking in aNew Wire Rope /45Wire Rope and Operations Inspection / 45Strength Loss of Rope Over Sheaves or Stationary Pins / 47Fleet Angle / 48Factors Affecting the Selection ofWire Rope / 49Guideline to Inspections and Reports / 52Field Lubrication / 68Wire Rope Efficiency Over Sheaves. /70PHYSICAL PROPERTIES /73.Elastic Properties of Wire Rope / Design Factors / 76Breaking Strengths / 77 _O rdering Storing and Unreeling Wire Rope / 97A Glossary of Wire Rope Terms /99Wire Rope Fittings / 1 9Socketing / 12

. Shipping Reel Capacity / 125Weights of Materials / 126CONTENTS IN ALPHABETICAL ORDER /1283


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knowledgementsTabular data and accompanying reference drawings for wire rope clips wereprovided by The Crosby Group. All other illustrations used throughout were.furnished by member companies of the Committee of Wire Rope ProducersAISI . Drawings were prepared especially for this publication and are basedwholly or in part on graphic material that originally appeared in literature issuedseparately by various member companies of the Committee.Numericaland factual data, not otherwise credited, were obtained frompublished and unpublished sources supplied by the Committee AIS ) and by theWire Rope Technical Board WRTB).

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ntrodu tionma chine: an assemblage of parts . .. that transmit forces motion n energy oto another in some predetermined manner and to some desired end . ..

Webster s Third New International DictionaIn and of itself, wire rope is a machine. The geometry--{)r configuration--{)f itcross-section and the method and material of its manufacture are preciselydesigned to perform in some predetermined manner and to some desired end.Hence, as befits any useful machine, it is imperative that the rope s potential ube fully recognized, that its functional characteristics be understood, and thatprocedures for proper maintenance be scrupulously adhered to. ygiving actirecognition to these generally accepted concerns, the user can be reasonablycertain that maximum service life and safety will be realized for every ropeinstallation or application.Full recognition of the inherent use-potential for wire rope derives fromrealization of the great number and wide variety of ropes available for generalspecial operating needs. Every particular style in all sizes, constructions, gradeand cores is designed to meet some special set of functional requirements.Fabricated to close tolerances, wire rope is inspected at all significantmanufacturing intervalsto assure the user of a uniformly high quality product.

Athoroughunderstandingof wire rope characteristics is of course,a primessential. This involves intimate familiarity witlioperating conditions, loadfactors, rope grades, and constructions.Immediately after manufacture, wire rope care becomes an overriding,necessity. At no point can aproper regard forcare and maintenance be neglecit must be exercised in handling, shipping, storage, and in installation. Then,after the rope is put into operation, approved maintenance practices and rigorinspection (qf both the rope and its associated equipment) must be carried ouon a continuous basis. Only strict adherence to these procedures can the rooperate with safety and effiCiency throughout its entire life span.Prepared for the long-time user as well as those unfamiliar with the produor its technology, this publication represents a joint effort by the wire ropeindustry. Those who already have a working knowledge of wire ropes will findin these pages a comprehensive and convenient source of reference data on suareas as properties and characteristics, handling, storage, operation andmaintenance in short, a handy checklist.As for the not-too-well informed or new user, this publication can serveas a broad-ranging introduction. Fo r these readers, the information provided chelp establish sound practices; practices of selection and application that are aonce safe, efficient and economic.As a cooperative industry effort, this manual brings together a significantportion of the enormous collection of data now scattered about in th e filesand publications of many individual companies. The text offers manyrecommendations, both explicit and implied. bu t these have been made solelyfor the purpose of providing some initial judgment point from which ultimatedecisions as to design and use may be made. The reader is urged to consult withe wire rope manufacturer as to the specific application planned. Themanufacturer s experience can then help the user make the most appropriate5


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choice. In the filial analysis, responsibility for design and use decisions rest withthe user. .The selection of equipment or components frequently influenced by the

special demands of an industry. An equipment manufacturer may, for reasons ofspace, econom.y, etc., feeic0111pelled to depart from suggested proceduresgiven in these pages. It important to remember that such variations fromrecommended practices should be regarded as potential dangers. However, whensuch circumstances are unavoidable they demand compensating efforts on thepart of the user. These extras should include but not necessarily be limited tomore frequent and more thorough inspections by skilled, specifically trainedpersonnel. Additionally, these circumstances may demand the keeping of speciallubrication and mainteriaricerecords, and the issuance of special warningsregarding removal and replacement criteria.


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2 asic omponents

(STRAND

;.; .

Figure 1. The three basic components of atypical wire rope.

Wire rope consists of three essential components. These, while fewin number ,vary in both complexity and configuration so s to produce ropes for specificpurposes or c h r ~ c t e r i s t i c s Basically, these three components of a standard wirerope design are: 1) wires that form the strand, 2) a core and 3) the multi wirestrands laid helically around the core (Fig. 1) .

Wire for rope, s made in several materials and types; these include steel,iron, stainless steel, monel, and bronze. By far, the most widely used materials high-carbon steel. This s available in a variety of grades each of which hasproperties related to the basic curve for steel rope wire. (Wire rope manufacturselect the wire type that s most appropriate for requirements of the finishedproduct.)

iron typ wire s actuaEy j,jh -carbon steel and has fairly limited useexcept for older elevator installations. However, when iron s used for other thaelevator application, it s most frequently galvanized.Steel wire strengths are appropriate to the particular grade of the wire rope inwhich they are used. These grades of wire rope are traction steel, mild plow steelplow steel, improved plow steel, and extra improved plow steel. (While steel granames originated at the earliest stages of wire rope devt lorment, they ~ ; V e beenretained and serve as indicators of the strength of a particular size and grade ofrope). The strength of plow steel forms the basis for calculating the strength of asteel rope wires, and the tensile strength of any grade s not constant, but varieswith the diameter-being highest for the smallest wires.

The most common finish for steel wire s bright or uncoated. Steel wiresmay also be galvanized (zinc coated). Drawn galvanized wire has the samestrength s bright wire, but wire galvanized at finished size s usually 10%lower in strength. In some special applications, tinned wire s used. but it shoulbe noted that tin provides no sacrificial (cathodic) protection for the steelas does zinc.

Listed in order of frequency of use, stainless steel ropes are made of AISITypes 302/304, 316, and 305. Contrary to general belief, hard-drawn stainlesType 302/304 is magnetic. Type 316 s less magnet ic and Type 305 has apermeability low enough to qualify s non-magnetic.

Monel Metal wire s usually Type 400 and conforms to FederalSpecification QQ-N-281.

Bronze wire s usually Type A Phosphor Bronze (CDA 510) althoughother bronzes are sometimes specified.

The core s the intrinsic foundation of wire rope; and s made of materialsthat will provide proper support for the strands under normal bending andloading conditions. Core materials include fibers (hard vegetable or synthetic)steel. The steel core consists either of stranded wires or of another independentwire rope. The three most commonly used core designations are: fiber core(FC), independent wire rope core (lWRC). and strand core (WSC) (Fig. 2).Catalog descriptions of the various available ropes include these abbreviationsto identify the type of core.

Strands are made up of two or more wires, laid in one of many specificgeometric arrangements. or in a combination of steel wires with some othermaterials such s natural or synthetic fibers. Although it s conceivable that a7


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strand can be made up of any number ofwires or that a rope can have any numberof strands in the United States the majority of wire ropes are designed with sixstrands. Major U.S. strand classifications are 7- 19- 37- 61- 91- and 127-wire.

Despite their numerical characteriiations it should be noted that theclassifications do not necessarily refer t the actual wire count in each strand.In standard manufacturing practice rope constructions do not necessarily havethe specific wire counts given by their respective classifications. The followingsection WIRE ROPE IDENTIFICATION provides a complete descriptionof the construction of each classification.

To summarize: a wire rope consists, in most cases, of three components:wires, strands, and a core Fig. 2 . To these may be added what may beconsidered a fourth component: the wire rope s lubric nt factor vital to thesatisfactory performance of most operating ropes.

FIBER FC INDEPENDENTWIRE ROPOR IWRCWIRESTRANDWSC

Figure 2. The three basic wire rope cores. Inselecting the most appropriate core for agiven application a qualified manufacturershould be called upon for guidance Fibercores for example are not recommended forapplications involving elevated temperaturesor high peak loads.

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Wire Rope Identification n onstructionWire rope is identified not only by its component parts, but also by constructLe by the way the wires have been laid to form strands, and by the way thestrands have been laid around the core.

In Figure 3 drawings a and c show strands as normally laid into therope to the right-in a fashion similar to the threading in a right-hand bolt.Conversely, the left lay rope strands (drawings b and d ) are laid in theopposite direction.Again in Figure 3 the first two drawings a and b ) show regular layropes. Following these are the types known as lang lay ropes. Note that the wirin regular lay ropes appear to line up with the axis of the rope; in lang lay ropethe wires form an angle with the axis of the rope. This difference in appearancea result of variations in manufacturing techniques: regular lay rope's aremade so that the direction of thewire lay in the strand is opposite to the directioof the strand lay in the rope; lang lay ropes c and d ) are made with bothstrand lay and rope lay in the same direction. Finally, the type e calledalternate lay consists of alternating regular and lang lay strands.

a

d Fi llre 3. A comparison of typical wire rope Jays: a) right rl gular ray b) Il ft rl glliar ray

right lang lay d) Il ftlang lay e right altanCltl lay.

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R GUL R L Y

_ I\

. Of all wire rope types in current use right r gul r l y is found in the widestrange of applications. Many applications related to excavation constructionor mining require l ng lay rope. Currently l ft l y rope is used less frequently.In any case where left lay and/or lang lay are required the manufacturer/suppliermust be so informed before ordering. As for lt rn t l y ropes theseare used for special applications.

Circumstances that favor the use of lang lay ropes derive from two uniqueadvantages over regular lay ropes. Lang lay ropes: 1 are more resistant tobending fatigue and 2 have a greater wearing surface per wire across the crownof the strand. The total wearing surface area of the rope is for practical purposest he same f or both regular and lang lay ropes with the same geometricconstruction and depth of wear the eventual wear on the equipment and theservice life of the rope favors laI1glay construction on applications wherefatigue or abrasion are controlling factors.

To illustrate this point Figure 4 compares a regular lay with a lang lay ropeeach of which has been w or n t o the same amo un t of reduction in theirrespective diameters.

Hence it is not the total of the rope s worn surface area that governs thelife span of rope and equipment. is rather the inherent characteristics ofproperly used lang lay ropes that gives them a significant advantage in resistanceto both abrasion and fatigue.

However lang lay ropes have some disadvantages. They are moresusceptible to damage resulting from: handling abuses bending over extremelysmall sheaves pinching in undersize sheave grooves crushing when improperlywound on drums and they are subject to excessive rotation. In fact this lattertendency for the rope and the strands to unwind in the same direction requires thatlang lay ropes should be secured at both ends to prevent unlaying or spinning out.

Preforming is a wire rope manufacturing process wherein the strands andtheir wires are shaped during fabrication to the spiral form that they willultimately assume in the finished rope or strand.

As previously noted wire rope strands are made up of a number of wires.

F ig ur e 4 . A c om pa ri so n of wear characteristics hetween l //IR l y and r{ Rular l y rdpes. The line a-b indicates the rope axis.


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The wire arrangeme nt in the strands will determine the rope s functionalcharacteristics, i.e., its capacity to Dleet the operatjng conditions to which it wibe subjected. There are many basic design constructions around whichstandard wire ropes are built; some of these are shown in Figure 5.

Four typical strand cross-sections, designed around the Warrington, Sealand Filler Wire basic constructions are shown in Figure 6

Wire ropes are identified by a nomenclature that is referenced to: 1 thenumber of strands in the rope, 2 the number nominal or exact andarrangement of wires in each strand, and 3 a descriptive word or letter indicatthe type of construction. i.e., geometric arrangement of wires Fig. 7 .

Under the earlier section BASIC COMPONENTS, mention was madeconcerning the manner in which wire rope constructions are grouped or classifThe most widely used classifications are listed and described in Table 1.

At this point, it may be useful to discuss wire rope nomenclature insomewhat greater detail. is a subject that may easily generate somemisunderstanding. The reason for this stems from the practice of referring torope either by class or by its specific construction.

Ropes are classified both by the number of strands and the nurriber of wirein each strand, e.g., 6x7, 6x19, 6x37 ,8 x J 9, J 9x7, etc. However, these are nomiclassifications that mayor may not represent the actual construction: Fo r examthe 6x19 class commonly includes constructions such as 6x21 filler wire, 6,,25 fwire,and 6x26 Warrington Seale. Despite the fact that none of these have, 19wires, they are designated as being in the 6x19 classification.

Hence, a supplier receivingan order f or 6x 9 rope may assume this to be al ss reference and is legally justified in furnishing any construction within thiscategory. But, if the job should require the special characteristics of 6x25 W, ana 6 x1 9 Se al e F ig . 5 is supplied in its stead, a shorterservice life can be expect

To avoid such misunderstanding, the safest procedure is to order a specifconstruction if such geometry is essential for the intended purpose, or to order

, both by class and construction, e.g., 6x19 6x26 Warrington Seale).Identifying wire rope in l ss groups facilitates selection on the basis of

strength, weight/ft. and price since aU ropes within a class have the same nomstrength, weight/ft a nd p ri ce . As for other functional ,characteristics, these canbe obtained by referencing the specific construction within the class.

Only three wire ropes in the 6x19 classification actually have 19 wires:6x19 2 operation, 6x19 Seale, and6x19 Warrington. All the rest have differecounts. There is a greater proportion of 37-wire constructions in the 6x37 clabut these are infrequently produced. The more commonly available 6x37constructions include: 6x31 Seale. 6x31 Warrington Seale WS . 6x36 WS,6x4l Seale FiUerWire SF W), 6x41. WS, 6 x4 3 F W, 6x46 WS, etc,-none ofwhich contains 37 wires.

While a strand s interior has some significance. its important characterisrelate to the number and, in consequence, the size of the outer wires. This isdiscussed in somewhat greater detail in the section titled FACTORS AFFECTTHE SELECTION OFWIRE ROPE p. 49 .


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Wire rope nomenclature also defines: length, size Le., diam.), type, directionof lay, grade of rope, type of core. and whether it is preformed (p/f) ornon-preformed (np/f). I f the direction and type of lay are omitted from therope description, it is presumed to be. a right regular lay. In addition, if no mentionis made as to preforming, this will be presumed as a requirement .for preforming.On the other hand, an order for elevator rope requires an explicit statementsince p/f an d np/f ropes are used extensively.

An example of a complete description would appear thus:6 00 f t 6x25 FW Left lang lay

Improved plow IWRC ope described above would be madePREFORMED

\ . ~;i ::.t :: ;> : ft:,....6125 FW

Figure 5. Basic constructions around which standard wire ropes are built.

i e s :eo: :; :;:x:;:. : :0; ' : i : e: ll r ~

6.21 SEALE WITHWITH IWRC

\\t . t::e.e::: :teE : ~ : . . . : ::J :; te6.31 WARRINGTONSEALE WITH IWRC

Figure 6. A fewcqmbinations of basic design constructions.

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SEALE STRAND19 WIRE SEALE

19 9

Figure 7. A singlewire rope strand. Wirerope is identified by reference to its numberof strands, as well as the number and geometric arrangement of wires in the strand.


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T BLE I WIRE ROPE CL SSIFIC TIONSBased on the Nominal Number of Wires in Each Strand

.

Classification6x7

. 6x19

6x376x61

6x91

6x127

8x19

19x7and18x7

DescriptionContaining 6 strands that are made up of 3 through 14wires, of which no more than 9 are outside wires.Containing 6 strands that are made up of 5 through 26wires, of which no more than 12 are outside wires.

Containing 6 strands that are made up of 27 through 49wires, of which no more than 18 are outside wires.Containing 6 strands that are made up of 50 through 74wires, of which no more than 4 are o u t s i d ~ wires,

Containing 6 strands that are made up of 75 throughl 09wires, of which no more than 30 are outside wires.Containing 6 strands that are made up of 110 or morewires, of which no more than 36 are outside wires.Containing 8 strands that are made up of 15 through 26wires, of which no more than 12 are outside wires.Containing 9 strands, each strand is made up of 7 wires. is : llanufactured by covering an inner rope of 7x7 leftlang lay construction with 12 strands in right regular lay.Therotation-resistant property that characterizes thishighly specialized construction is a result of the countertorques developed by the two layers.) When the steel wirecore strand is replaced by a fiber core, the decriptionbecomes 18x7.

When centerwire is replaced by a strand, it is considered as a single wireand the rope classification remains unchanged.There are, of course, many other types of wire rope, but they are usefulonly in a limited number of applications and, as such, are sold as specialties.Usually designated according to their actual construction, some of these specialconstructions are listed in Table 2 and shown in Figure 8


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5119 M RLINE L D 6 4 TILLER ROPE

Figure 8. Three special purpose constructions that suggest wire rope s inherentdesign potential.

TABLE 2 SPECIAL CONSTRUCTIONS3x7 Guard Rail3x19 Slusher6x12 Running Rope6x24 Hawsers6x30 Hawsers6x42 6x6x7 TiIle.r Rope6x3x19 Spring Lay5x19 Marline Clad6x19 Marline Clad

Tab le 2 s a much abbreviated listing of ropes designed for highly speciaiizedapplications. Within the scope of this publication it s not feasible to list themany uses nor to describe the possible design variations.

Cro ss -se ct ion s o f wire r op e s hown in Fig ur es 9 a nd 1 0 are a mo ng t he m os tcommonly used and they are arranged in their respective classification groups.Because they are in greater demand they are more generally available.

There s however one specialized wire rope category that requires somediscussion here elev tor rop In this application selecting the right roperequires more than ordinary care.

Elevator rope can be obtained in four principal grades: 1 iron. 2 tractionsteel 3 high-strength steel and 4 extra-high-strength steel. In addition. bronzerope is sometirnesused for a limited number of functions within this category.It should be noted that demand for the iron grade is decreasing markedly andits use s gencralJy limited to older existing equipment.

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Figure 9. Cross-sections of some commonlyusedwire rope constructions.

6 7 WITH FIBER CORE6 x7 CLASSIFICATION

. ..A ' ' ....... } . : : :...... ~ t. .e G;,&$. e l e ~ ~ .... f i.:......... .. .6,25B FLATIENED STRANDTRIANGULAR CENTER WIRE.... .......

: ~ : ~ : ~ : ..... .. .: : ....... ... .......: ;.............. ..... ....... ..... ......i x30 GFLATTENED STRANDBRANGLED CENTER 6 x19 CLASSIFICATION

. ..:.:.. ... .:e:- . .:..: .e.:e -, e:e:.,. ....: : xl 9 SEALE WITH IWRC. ~ ~ . ....:.... ... .. ,' , ...i ~ . i ~ . .e l.,.:i:::',:::. 1:.-... .. ..-:.:~ 6,25 FILLER WIREWITH IWRC 6 2 6 WARRINGTONSEALE WITH IWRC

~ .... e t . ~ ~ e ; , ~ - . J 1 I : ~ ..... ..:::.:......:;:: :: : 0:':::',' . . . . . ..... . . . l ..... ......,,3 1 FI.LLER WIREWITH IWRC .

~ . R . :. i e................... :i::::i: E ~ . .:...:::.\

l 6 3 i WARRINGTON SEALEWITH'IWRC ....... .... ......: i r : . r . . ~ ~ ~ . ~..........'...:-;:.:= :-.:.: : : J . ::::::::: ...... ........ . te....: . . .... . ~ : . : . ' ...... ...6,41 SEALE FILLERWIRE WITH IWRC

\ . . ~ ~ ..... ~ 4 ' . . ., . : ~ : : : . . . . . ~ : : - : - ..:,.-::::::::: 1. : :. ........:......, ;............ ' .:. .P .. .....

6 3 6 FILLER WIREWITH IWRC ~ : . : ~.: . . ~ . . . . :. : ....' : ... ~ ~ ; ; / : :i: ..: :: :: :i:: ::i: ..':.:.................. ...... ....:. . 4 6 SEALE FILLERWIRE WITH IWRC 6,49 FILLER WIRE SEALWITH FISER CORE

Also manufactured as 6x27H and 6x25B. Alsomanufactured as 6x27V.

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6:x37 CLASSIFICATION


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The mostwidely used constructions forelevatoTT9pe are.6x25 FW, .8xI9 Seale, and 8x25 FW. But,on occasion, anumber of other constructions r, . ; I . 1 ~used. In any case, these ropes differ significantly from one another in their wearand fatigue characteristics, thus they should not be inter-changed indiscriminately.There are in fact some a p p l i c a t i o n s ~ s u c h sgovernor rope where the ropesm y not be interchanged either in grade or construction without re qualification.A special construction 6x42) is still used from time to time a hand ropeto control the elevator, and small diameter ropes of 7x 9 construction areused as control ropes for operating floor selection equipment.

From reel to reel, there are slight yet significant differences in the elasticproperties of wire rope. Because of such possible variations, it is stronglysuggested that all rope for a given elevator be obtained from a single reel.Recognizing the need for such precaution, many codes and purchasingspecifications make this a standard requirement.As noted, it is beyond the scope of this publication to discuss, in depth, designand selection considerations for elevator rope. Information concerning sheavediameters, design factors ratio of nominal strength to working load), groovecontours, etc. can be found in the ANSI Code Al 7.1.To obtain current data and sound technical guidance on elevator rope orany other special requirements, a reputable wire rope m a n u f a c t u r e ~ shouldbe consulted.

~ ~ . ~....:l fI t; etl f ~ 1 ~ t = - eW b ':e l:iji eO:::. . . . O: :1817 ROTATION RESISTANT 19>7 ROTATION RESISTANTWill i FIBER CORE WITH WIRE STRANO CORE

I ~ J 7 a 1917 CLASSIFICATIONS

.\, ..1::::. : :. r ; it.eM _ -:.-:-.:- eif:-. . ..: : :... e . ~ A'yti , W8 I Z5 FILLER WIREWITH IWRC8 9 CLASSIFICATION

. p4t :. - f :- iJ .:i:. . -\.. \..: :. ...............' --:i:-- . - . .; : . , ~ \ : ;. :8 9 SEALE WITHIWRC

Figure 10. Cross-sections of wire ropes designed for specific functions. Note that the tworotation resistant constructions are identical except for the core--one of which is wire strandand the other fiber. The wire strand core increases the number of strands.from 8 to 19.

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Handling Wire RopeRECEIVING INSPECTION ND STOR GEThe right time to start appropriate.care and handling procedures for wire ropeis immediately on delivery. When th,e rope arrives it should be carefully checkefor size construction and core making certain that the delivered product matcthe description on the tags requisition forms packing slips purchase orderand invoice.Following these preliminaries the question of storage should be considere the wire rope is to be held for a considerable time before being used it musbe protected from the elements. A dry well-ventilated building or shed is aproper storage place. Avoid closed unheated tightly sealed buildings because. condensation will form on the rope when warm moist outside air envelops thcolder rope. Although wire rope is protected by a lubricant this is nottotallyeffective since condensation can still occur within the small interstices betweenstrands and wires thereby creating corrosion problems.

If on the other hand the delivery site precludes the use of an inside storaspace and the rope must be kept outdoors it should be suitably covered witha waterproof material. Weeds and tall grass should be cut in the assigned storagarea and the reel itself should be on a platform elevated so as to>keep it fromdirect contact with the ground. Providing an adequate covering f r the reel wilalso prevent the original lubricant from drying out with a resuit;:;,rjt loss ofprotection.

Wire rope should never be stored in areas subject to elevated temperatureDust grit or chemically laden atmosphere are also to be avoided. Although thelubricant applied at the factory offers some degree of protection every normalprecaution should be taken with each coil or reel of wire rope.

Whenever wire rope remains in position on an idle machine cr ane hoistetc. it should be coated with an appropriate protective lubricant. n thesecircumstances as with ropes stored outside moisture in the form of condensatrain or snow may form on the wire rope. Some of the moisture may easilybecome t ra ppe d inside the rope and cause corrosion problems. .

the wire rope is to be kept inactive for an extended period while wounon the drum of the idle equipment it may be necessary to apply a coating of. lubricant to each layer as the rope is wound on the drum; Cleaning inspectionre-Iubrication should precede start-up o the equipment.

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WIREROPE INSTALLATIONCHECKING THE DIAMETERIt is most important to check the diameter of the delivered rope before installation.:This is to make certain that the rope diameter meets the specified requirementsfor the given machine or equipment. With an undersize diameter rope, stresseswill be higher than designed for and the probability of breaking the rope willbe increased; an oversize diameter rope will wear out prematurely. This happensbecause of abuse to the rope caused by pinching in the grooves of the sheaveand drum.

In checking, however, the true rope diameter must be measured. And thisis defined as the diameterof the circumscribing circle, i.e., its largest cross-sectionaldimension. To insure accuracy this measurement should be made with a wirerope caliper using the correct method b) shown in Fig. 11. For measuringropes with an odd number of outer strands, special techniques must be employed.

Design specifications for wire rope are such that the diameter is slightly largerthan the nominal size, accqrdingto the allowable tolerances shown in Table 3.TABLE 3OVERSIZE LIMITS OF WIRE ROPE DIAMETERS*

Nominal Rope Diameter Allowable LimitsThru ;;a 0 +8

Over Ih thru 0 +7Over thru 1 4 0 +6Over 1 4 and larger 0 +5

*These limits have been adopted by the Wire Rope TechnicalBoard WRTB). and are being considered for inclusion in theforthcoming revised edition of Federal Standard RR.W410.In the case of certain special purpose ropes, such as aircraftcables and elevator ropes, each has specific requirements.

TRUE DIAMETER

~1 ~ 1 i .fI ::Wly ~ - a : 81\ :l , : . : ; : - . : ~ m ' ~ 1 1 ~ \ l ;---A

B. CORRECT C. INCORRECT

Figure 1I. How to measure (or caliper) a wire rope correctly. Since the true diameter (a)lieswithin the circumscribed circle, always measure the larger dimension (b).18


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UNR LIN AND UNCOILINGWire rope is shipped in cut lengths, either in coils or un reels. Great care shoube taken when the rope is removed from the shipping package since it canbe permanently damaged by improper unreeling or uncoiling. Looping the ropover the head of the reel or pulling the rope off a coil while it is lying on theground, will create loops in the line. Pulling on a loop will, at the very least,produce imbalance in the rope and may result in open or closed kinks Fig. 12 Once a rope is kinked, the damage is permanent. To correct this condition, thekink must be cut out, and the shortened pieces used for some other purpose.

Figure 12. Improperhandling will help create open a or closed b kinks The open kinwill open the rope lay; the closed kink will close it. The starlin loop Cc : do not allow the rto form a small loop. f however. a loop forms and is removed at the point shown, a kinkwbe avoided. The n Cd : here the looped rope has been put under tension, the kink hasformed, the rope is permanently damaged and is of little value.


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PREFERRED

REEL

LLOWABLE IF NOT CLOSE COUPLEOFigure 15. Winding wire rope from reelto drum.nwin ing wir rope rom its r l also requires careful and proper procedure.There a re three methods to perform this step correctly:

1 The reel is mounted on a shaft supported by two jacks or a roller payoffFig. 13 . Since the reel is free to rotate the rope is pulled from the reel by workman holding the rope end and walking away from the reel as it unwinds.A braking device should be employed so that the rope is kept taut and thereel is restrained from over-running the rope. This is necessary particularlywith powered e ~ r e e l i n g equipment.

2 Another method involves mounting the reel on an unreeling stand Fig. 14 .It is then unwound in the same manner as described above I . In this casehowever greater care must be exercised to keep the rope under tensionsufficient to prevent the accumulation of slack a condition that will causethe rope to drop below the lower reel head.3 In another accepted method the end of the rope is held while the reel itselfis rolled along the ground. With this procedure the rope will payoff properly;however the end being held will travel in the direction the reel is being rolled.As the difference between the diameter of the reel head and the diameter ofthe wound rope increases the speed of travel will increase.

i ~ u t e i3. The wire rope teeI is mounted on a Shaft supported by jacks. This permits the reelto rotate freely. and the rope can be unwound either manually or by a powered mechanism.20

Figure 14. A vertical unreeling stand.


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When r ~ r l i n wire rope from a horizontally supported reel to a drum, it ispreferable for the rope to travel from the top of the reel to the top of thedrum; or, from the bottom of the reel to the bottom of the drum Fig. 15Re-reeling in this manner will avoid putting a reverse bend into the ropeas it is being installed. a rope is installed so that a reverse bend is induced,it may cause the rope to become livelier and, consequently, harder to handleWhen unwinding wire rope from coil there are two suggested methods fo

carrying out this procedure in a proper manner:1) One method involves placing the coil on avertical unreeling stand.The stand consists of a base with a fixed vertical shaft. On this shaft thereis a swift, consisting of a plate with inclined pins positioned so that the comay be placed overthem. The \vhole swift and coil then rotate s the ropeis pulled off This method is particularly effective when the rope is to bewound on a drum.2 ) The most common as well as the easiest uncoiling method is merely to holdone endof the rope while rolling the coil along the ground like a hoop Fig. 1Figures 17 and 18 show unreeling and uncoiling methods that are mostlikely to provide kinks. Such improper procedures should be strenuously avoi

in order to prevent the occurrence of loops. These loops, when pulled taut, willinevitably result in kinks. No matter how a kink develops, it will damage stranandwires, and the kinked section must be cut out. Proper and carefiirliandIingwill keep the wire rope free from kinks.

Figure 16 Perhaps themost common andeasiest uncoiling method is to hold oneend oft he ropewhile the coil is rolled along theground. Figure 17. I llus tr at inga wrong method ofunreeling wire rope.

Figure18 Illustrating a wro method ouncoiling wire rope.


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Figure 19. METHOD A Lay one end of theseizing wire in the groove between two strands;wrap the other end li tly in a close helix overn position of the groove using a seizing iron(a rOl lnd bar 2 to diam. x 18 long) asshown above. Both ends of tbe seizing wireshould be twisted together tightly, and tbefinished appearance as shown below. Seizingwidths should not be less than the ropediameter. METHOD B The procedureillustrated at right is the second of the two(A and B) accepted methods for placingseizing on wire rope.

S IZIN WIR ROP While there are numerous ways to cut rope, in every case. certain precautions ust be observed. For one thing, proper se izings are always applied on bothsides of the place where the cut is to be made. In a wire rope, carelessly orinadequately seized, ends may become distorted and flattened. and the strandsmay loosen. Subsequently, when the rope is put to work. there may be an unevendistribution of loads to the strands; a condition that will significantly shortenthe life of the rope.

There are two widely accepted methods of applying seizing (Fig. 19). Theseizing itself should be a soft, or annealed wire or strand. The seizing wire diameterand the length of the seize will depend on the diameter of the wire rope. Butthe length of the seizing should never be less than the diameter of the rope beingseized. For preformed rbpes, one seizing on each side of the cut is normallysufficient. But for those that are not preformed. a minimum of two seizings isrecommended (Fig. 20). Seizings should be spaced 6 rope diameters apart.

Table 4 lists seizing lengths and seizing wire diameters suggested for usewith some commonly used wire ropes.


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TABLE 4 S IZINGSuggested iameters and Lengths:: :

Rope Diameters Seizing Wire Diameters Seizing Lengthsinches mm inches mm inches mm

V s ~ l j 1 6 3.5-8.0 .032 0.813 6.0 ~ 6 9.5-14.5 .048 1.21 1 6 13.00/8 _10/10 16.0-24.0 .063 1.60 19.01-1 26,0-33.0 .080 2.03 11 4 32.0

1 -111;10 5.0-43.0 .104 2.64 1 44 01 -21,6 45.0-64.0 .124 3.15 21 6 64.0

.;;2 ~ 0 3 1 6 65.0-89.0 .124 3.15 3 th 89.0

*The diameter of seizing wire for elevator ropes is generally smaller than indicated in thistable. The wire rope manufacturer should be consulted for recommended,sizes.

23


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UTTINGWffi ROPWire rope i s ~ u t f t r being properly s e i z ~ Fig. 20 Cutting is a reasonablysimple operation provided appropriate tools are used. There are several types ofcutters and shears commercially available. These are specifically designed tocut wire rope.

Portable hydraulic and mechanical rope cutters are available. In remoteareas, however, it may at times be necessary to use less desirable cutting methods.For example, using an axe or hatchet must be recognized as dangerous.

NONPREFORMED

~ ~EFORE CUTTING~FTER CUTTING

~ I I I I l I I I I I I I ~PREFORMED I

~ ~ ~EFORE CUTTING I

~ E ~ ~FT R UTTIN

Figure 20. Seizings, either on non-preformed or preformed wire rope, are applied for cutting.


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: : d > ~ ~ ~ , , - , ; , , ~ ~ - , . ~ ~ ~ , = - ~WIRE ROP SOCKET SPELTER OR RESIN ATTACHMENT

WIRE ROPE SOCKET SWAGED

~ ~ ~ ~ ~MECHANICAL SPLICE LOOP OR THIMBLE ATTACHMENT

WEDGE SOCKET

CLIPS NUMBER O CLIPS VARIES WITH ROPE SIZE

n ~ ~LOOP OR THIMBLE SPLICE HAND TUCKED

igure End fittings or attachments are available many designs some of which weredeveloped for particular applications he six shown are among the most commonly used6


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- , . - ~ - - ~ ~ - - - , ~ - ~ - ~

TABLE 5 TERMINAL EFFICIENCIES APPROXIMATEEfficiencies r based on nominal :strengths

Method of Attachment. Efficiency

Rope with IWRC* Rope with FCWire Rope Socket-Spelteror Resin Attachment

Swaged SocketMechanical Spliced Sleeve

1 dia. and smaller11A3 dia. thru 12 dia. and larger

10095

9592 Ih90

100(Not establish

92V2908 iZ

9089888786848280

80797877 .76 '747270

Loop or Thimble Splice-Hand Spliced (Tucked)(Carbon Steel Rope)'~0/16

'iZ

thru2'iZLoop or Thimble Splice-Hand Spliced (Tucked)(Stainless Steel Rope)

l}166Ih

0/8

Wedge Sockets***(Depending on Design) 75 to 90Clips***(Number of clips varies with size of rope) 80. *IWRC = IndependentWire Rope Core **FC = Fiber Core

***Typical valueswhen applied properly.Refer to fittingsmanufacturers for exact values and method.

27

9089888786848280

75 to 90

80


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U BOLT IST RIP

SOCKETINGImpropetly attached wire rop e te;:rminals lead to serious-possibly unsafeconditicms. To perform properly alI wire rope elements must be held securelyby the terminal. If this is not accomplished. the strands will loaf on the joband there is every likelihood that a strand will become high . A high strandcondition is illustrated in Figure42. In the case shown. selective abrasivewear of the loose strand will necessitate early removal of the rope.Poured Sockets-SpeIter or ResinWhen preparing a wire rope for socketing. it is of extreme importance to followrecommended procedures. (See Appendix D: SOCKETING PROCEDURES.)Procedures other than those stipulated here. may develop the required strengthbut this cannot be pre-determined without destructive tests. I t is far safer-and ultimately less costly-to follow well-established practices.There are many ways to go wrong in socketing procedures. Some of themore common pitfalls that should be guarded against include:I ) Turning back the strands-inward or outward-before the broom is

inserted into the socket;2) Turning back the strands and seizing them to the body of the rope;3) Turning back the strands and tucking them into the body of the rope;4) Tying a knot in the rope;5) Driving nails, spikes, bolts, and similar objects into the socket after the rope

is in, so as to jam it tight; this is particularly dangerous-and ruinous. oavoid these and many other dangeroLls practices play it safe by followingcorrect procedures.

WIRE ROPE CLIPSWire rope clips are widely used for attaching wire rope to haulages, mine cars,hoists, and for joining two ropes.Clips are available in two basic designs; the V bolt and fist grip (Fig. 23).The efficiency of both types is the same.

When using V boll clips. extreme care must be exercised to make certainthat they are attached correctly. i.e., the V bolt must be applied so that the Usection is in contact with the dead end of the rope (Fig. 24). Also. thetightening and retightening of the nuts must be accomplished as required.

Fil:ure 23. Wire rope clips are obtainablein two basic designs: V bolt and fist grip.Thei r efficiency is the same.

W T APPLYCLIPSU-BOLT CLIPS Table 6, page 30)Recommended Method of Applying U-Bolt Clips to Get MaximumHolding P ier of the Clip1 ) Turn back the specified amount of rope from the thimble. Apply the first clip

one base width from the dead end of the wire rope (U-bolt over dead end-liveend rests in clip saddle). Tighten nuts evenly to recommended torque.

2 Apply the next clip as near the loop as possible. Turn on nuts firm but donot tighten.

3) ,Space additional clips if required equally between the first two. Turn on ut -take up rope slack ---tighteh alI nuts evenly on alI clips to recommended torque.


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4) NOTICEl Apply the initial load and retighten nuts to the recommended torqRope will stretch and shrink in diameter when loads are applied. Inspectperiodically and retighten. .

A termination made in accordance with the above instructions and usingthe number of clips shown has an approximate 80 efficiency rating. This ratinis based upon the catalog breaking strength of wire rope. a pulley is used inplace of a t hi mb le f or t ur ni ng b ac k the r op e add one additional clip.

The.number of clips shown is based upon using right regular or lang laywire rope 6 x 19 class or 6.x 37 class fibre core or IWRC IPS or XIPS. Seal

. construction or similar large outer wire type construction in the 6 x 19 classis to be used f or sizes 1 i nc h a nd larger a dd o ne a dd it ion al clip.

The number of clips shown also applies to right regular lay wire rope8x 19 class fibre core IPS sizes 1 inch and smaller; and right regular lay wirrope 18 x 7 class fibre core IPS or XIPS sizes 13 and smaller.

For other classes of wire rope not mentioned above it may be necessary toadd additiqnal clips to the number shown.

a greater number of clips are used than shown in the table the amount orope turnback should be increased proportionately. ABOVE BASED ONUSE OF CLIPS ON NEW ROPE.

IMPORT NT Failure to make a termination in accordance withaforementioned instructions or failure to periodically check and retighten lOtherecommended torque will cause a reduction in efficiency rating.

RIGHT W Y OR M XIMUM ROP STRENGTH

WRONG WAY: CLIPS STAGGERED

W RO NG W Y CLIPS REVERSED

Figure 2 ; The correCI way 10 attach U-bolts is shown at the top: the U section is in conwith the rope's dead end.

29


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T LE 6*Min. no. Amount of TorqueClip of rope to Weight

Size A B C D E F G H :tlips turn back Ib/ft Ib/100 .22 .72 .44 .47 .41 .38 .81 .94 2 ~ 4.5 5.25 .97 .56 .59 .50 .44 .94 1.16 3 7.5 9

.31 1.03 ,50 .75 .66 .56 1.19 1.44 2 4 15 18 .38 1.38 .75 .88 ..72 .69 1.31 1.69 2 5 ~ 30 30 .44 1.50 .75 1.00 .91 .75 1.63 1.94 2 6 ~ 45 426 .50 1.88 1.00 1.19 1.03 .88 1.81 2.28 2 7 65 70

.50 1.88 1.00 1.19 1.13 .88 1.91 2.28 3 l ~ 65 75 .56 2.25 1.25 1.31 1.22 .94 2.06 2.50 3 12 95 100 .56 2.38 1.25 . 1.31 1.34 .94 .2.06 '2.50 3 12 95 100 .63 2.75 1.44 1.50 1.41 1.06 2.25 2.84 4 18 130 150 a .75 3.13 1.63 1.75 1.59 1.25 2.44 . 3.16 4 19 225 2401 .75 3.50 1.81 1.88 1.78 1.25 2.63. 3.47 5 26 225 250

~ .75 3.88 2.00 2.00 1.91 1.25 2.81 3.59 6 34 225 310 ~ .88 4.25 2.13 2.31 2.19 1.44 3.13 4.13 6 37 360 4601 .88 4.63 1.31 2.38 2.31 1.44 3.13 4.19 7 44 360 520

~ .88 4.94 2.38 2.59 ..53 1.44 3.41 4.44 7 48 360 59010/8 1.00 5.31 2.63 2.75 2.66 1.63 3.63 4.75 7 51 430 7301 1.13 5.75 2.75 3.06 2.94 1.81 3.81 5.28 7 53 590 9802 1.25 6.44 3.00 3.38 3.28 2.00 4.44 5.88 8 750 13402 1 1.25 7.13 3.19 3.88 . 3.94 2.00 4.56 6.38 8 73 750 15702 Ih 1.25 7.69 3.44 4.13 4.44 2.00 4.69 6.63 9 84 750 17902 1.25 8:31 '3.56 4.38 4:88 2,00 5.00 6.88 10 100 750 22003 1.50 9.19 3.88 4.75 5.34 2.38 5.3i 7.63 10 106 1200 3200

From TheCrosby Group30


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FIST GRIP CLIP S Tab le on following page)RECOMMENDED METHOD OF APPLYING FIST GRIP CLIPS1 Turn back the specified amount of rope from the thimble. Apply the first clione b as e width from the dead end o f the wire r op e. Tighten nuts evenly to

recommended torque.2 Apply the next clip as near the loop as possible. Turn on nuts firmly but do

not tighten.3 Space additional clips if required equally between the first two. Turn on u t

take up rope slack-tighten all nuts evenly on all Clips to recommended torq4 NOTICEl Apply the initial load and retighten nuts to the recommended torq

Rope will stretch and shrink in diameter when loads are applied. Inspectperiodically and retighten.A termination made in accordance with the above instructions, and usingthe number of clips shown has an approximate 80 efficiency rating. This ratin

is based upon the catalog breaking strength of wire rope. a pulley is used inplace of a thimble for turning back the rope, add one additional clip.The number of clips shown is based upon using right regular lahg laywire r op e, 6 x 19 class or 6 x 37 class, fibre core or IWRC, IPS or EIPS. Sealconstruction or similar large outer wire type construction in the 6 x 19 classis to be used for sizes 1 inch and larger, add one additional clip.

The number of clips shown also applies to right regular lay wire rope,8 x 19 class, fibre core, IPS, sizes II h inch and smaIIer; and right re gular lay wirope, 18 x 7 class, fibre core, IPS or EIPS, sizes 11 and smaIIer.

For other classes of wire rClpe not mentioned above, it may be necessary ,to add additional clips to the number shown.

a greater number of clips are used than shown in the table, the amountof rope turnback should be increased proportionately. ABOVEBASED ONUSE OF FIST GRIP CLIPS ON NEW WIRE ROPE.

1MPORTA T Failure to make a termination in accordance withaforementioned instructions or failure to periodically check and retighten to therecommended torque will cause a reduction in efficiency rating


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A ~ T L1 ~ M ~ L

TABLE 7

Min. no. Amount of TorqueClip L of rope to in WeightSize A C D E F G H Approx. M N clips turn back Ib/ft Ib/l00.25 1.25 .34 .94 .38 .50 1.28 .22 1.63 .69 1.47 2 4 30

0/10 .31 1.34 ,44 1.06 .38 .63 1.47 .19 1.94 .69 1.56 2 5 30 26.38 1.59 .50 1.06 ,44 .75 1.81 .25 2.38 .75 1.88 2 ~ 45 37.50 1.88 .56 1.25 .50 1.00 2.19 .28 2.75 .88 2.19 2 65 60 .50 1.88 .56 1.25 .50 1.00 2.19 .28 2.75 .88 2.19 3 65 600 .63 2.28 .69 1.50 .63 1.25 2.69 .28 3.50 1.06 2.63 3 12 130 110 .63 2.28 .69 1.50 .63 1.25 2.69 .28 3.50 1.06 2.63 3 3 ~ 130 110 .75 2.69 .88 1.81 .75 1.50 2.94 .31 3.75 1.25 3.06 3 16 225 140 a .88 2.97 .97 2.13 .75 1.75 3.31 .38 4.13 1.25 3.14 4 26 225 2201 1.00 3.06 1.19 2.25 .75 2.00 3.72 ,41 4.63 1.25 3.53 5 37 225 270Bis 1.13 3.44 1.28 2.38 .88 2.25 4.19 ,44 5.25 1.44 3.91 5 4 360 300

4 1.25 3.56 1.34 2.50 .88 2.50 4.25 .50 5.25 1.44 4.03 6 55 360 4101 1.50 4.13 1.56 3.00 1.00 3.00 5.56 .56 7.00 1.63 4.66 6 62 500 680 Y z 1.50 4.13 1.56 3.00 1.00 3.00 5.56 .56 7.00 1.63 4.66 6 66 500 680

*From The Crosby Group

3


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W G SO K TSOne of the more popular end attachments for wire rope is the wedge socket.For field, or on the job attachment, It is easily instaIJed and quickly dismantled.The procedure is simple:1 Inspect the wedge and socket; all rough edges or burrs, that might damage th

rope, should be removed.2 I f the end of the r op e is welded, the welded end should be cut off This will

allow the distortions of the rope strands, caused by the sharp bend around twedge, to adjust themselves at the end of the line. the weld is not cut off, thdistortions will be forced up the working line. This may result in thedevelopment of high strands and wavy rope.

3 Place the socket in an upright position and.bring the rope around in a large,easy to handle, loop. Care must be taken to make certain that the live-Ioadeside of the rope is in line with the ear s F ig . 25

4 The dead end of the rope should extend from the socket for a distanceapproximately nine times the rope diameter.The wedge is now placed in thesocket, and a wire rope clip is placed around the dead end by clamping ashort, extra piece of rope to the tail. Do not clamp to the live part. The should bear against the tail; the saddle of the clip should bear against the shorextra piece.

5 Secure the ears ofthe socket to a sturdy support and carefully take a strain othelive side of the rope. Pull the wedge and rope into position with tensionsufficiently tight to hold them in place.

6 After final pin connections are made, increase the loads gradually until thewedge is properly seated. Avoid sudden shock loads.

The foregoing is the recommended procedure. variations are made tosuit special conditions, they should be carefully evaluated beforehand.

WRONG

RIGHT

LIVE END

Figure 25. Th e wedge socket is a v er ypopularend attachment; it is easily installedand quickly dismantled. But it must beapplied correctly A .


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RUMS GROOVEDrums are the means by which power is transmitted to the rope and thence to theobject to be moved For the wire rope to pick up this power efficiently and totransmit it properly to the working end installation must be carefully controlled

If the drurn is grooved the winding conditions should be closely supervisedto assure adherence to the following recommended procedures: the end of the rope must be secured to the drum by such means as willgive the end attachment at least as much strength as is specified by the

equipment manufacturer2 Adequate tension must be maintained on the rope while it is being wound

so that the winding proceeds under continuous tension3 The rope must follow the groove4 There should be at least three dead turns remaining on the drum when the ropeis unwound during normaloperation Two dead turns are a mandatory

requirement in many codes and standardsf the wire rope is carelessly wound and as a result jumps the groovesit will be crushed and cut where it crosses from one groove to the other Another

almost unavoidable problem is created at the drum flange; as the rope climbsto a second layer there is further crushing and the wires receive excessive abrasionRiser and filler strips may help remedy this condition


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DRUMS PL IN (SMOOTH)Installation of a wire rope on a p l ~ n smooth face drum requires a greatdeal of care. The starting position s ?ould be at the drum end so that each tumof the rope will wind tightly against the preceding turn (Fig. 26 . Here too,close supervision should be maintained all during installation. This will help m. certain that:1 the rope is properly attached to the drum,2 appropriate tension on the rope is maintained as itis wound on the drum,3 each turn is guided as close to the preceding turn as possible, so that there

are no gaps between turns,4 and that there are at least two dead turns on the drum when the rope is fully

unwound during normal operating cycles.Loose and uneven winding on a plain- (smooth-) faced drum, can andusually does create excessive wear, crushing and distortion of the rope. The res

of such abuse are lower operating performance, and a reduction in the rope seffective strength. Also, for an operation that is sensitive in terms of movingand spotting a load, the operatorwill encounter controldifficulties the rope wpile up, puU into the pile and faU from the pile to the drum surface;: The .ensuing shock can break or otherwise damage the rope.

R

UNDERWIND L FT TO RIGHTUSE L FT L Y ROPE R

{1

OVERWIND L FT TO RIGHTUSE RIGHT L Y ROPE

L FT L YUNDERWOUNDI

RIGHT L YOVERWOUND

R

H

OVERWIND RIGHT TO L FTUS L FT L Y ROPE

L R

UNDERWIND RIGHT TO L FTUSE RIGHT L Y ROPE

L FT L YOVERWOUNDI

R GHT L YUNDERWOUND

j ~ r 26. By holding the right or left hand with index finger extended. palm up or palmdown, the proper procedure for installing lef and righ lay rope on a smooth drum can beasily determined.

35


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R

ROSS OV R

Figure 27. fter thefirst layer is woundon a drum. the point at which the rope windsback for each turn is called the cross over

The proper direction of winding the first layer on a smooth drum can bedetermined by standing behind the drum and looking along the path the ropetravels, and then following one oLthe procedures illustrated in Figure 26.The diagrams show: the correct relationship that should be maintained betweenthe direction of lay of the rope (right or left), the direction of rotation of thedrum (overwind or underwind), winding from left to right or right to left. RUMS MULTIPLEL Y RSMany installations are designed with requirements for winding more than one layerof wire rope on a drum. Winding multiple layers presents some further problems.

The first layer should wind in a smooth, tight helix which, if the drum isgrooved, is already established. The grooves allow the operator to work off theface of the drum, and permit the minimum number of dead turns.A smooth drum presents an additional problem, initially, s the wire ropemust be wound in such a manner that the first layer will be smooth and uniform andwill provide a firm foundation for the layers of rope that will be wound over it.The first layer of rope on the smooth drum should be wound with tension sufficientto assure a close helix each turn being wound as close s possible to thepreceding turn and most, if not all, of the entire layer being used as dead turns.The first layer then acts s a helical groove which will guide the successivelayers. Unlike wire ropes operating on groove drums, the rst layer should notbe unwound from a smooth-faced drum with multiple layers.

After the rope has wound completely across the face of the drum (eithersmooth or grooved), it is forced up to a second layer at the flange. The rope thenwinds back across the drum in the opposite direction, lying in the depressionbetween the turns of the rope on the first layer. Advancing across the drum onthe second layer, the rope, following the grooves formed by the rope on the firstlayer, actually winds back one turn in each revolution of the drum. The ropemust then cross two rope grooves in order to advance acrOss the drum foreach turn. The point at which this occurs is known as the cross overCross-over is unavoidable on the second, and all succeeding layers. Figure 27illustrates the winding of a rope on the second layer from left to right, andfrom right to left the direction is shown by the arrows.

tthese cross-over points, the rope is subjected to severe abrasion andcrushing as it is pushed over the two rope grooves and rides across the crown ofthe first rope layer. The scrubbing of the rope, as this is happening, caneasily be heard.

There is, however, a special drum grooving available that will greatlyminimize the damage that can occur atcross over points.Severe abrasion can also be reduced by applying the rule for the correct rdpe

lay (right- or left-lay) to the second layer rather than to the first layer. is forthi reason that the first layer of a smdoth drum should be wound tight andused as dead turns.

36


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Operation n aintenance of Wire Rope


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TABLESMAXIMUM ALLOWABLE RADIAL BEARING PRESSURES OF ROPES ONVARIOUS SHEAVE MATERIALS pOUNDS PE R SQUARE INCH--PSI : > OJ

Regular Lay Rope psi Lang Lay Rope psi FlattenedStrandLang LayMaterial 6 x 7 6 x 19 6x37 8 x 19 6 x 7 6 x 19 6 x 37 psi RemarksWood 150 250 300 350 165 275 330 400 On end grain ofbeech hickory gum.Cast tron 30 0 480 585 680 350 550 660 800 Based on minimumBrinell hardness of 125.

30-40 Carbon. BasedCarbon Steel Casting 55 0 900 1 075 1 260 600 1 000 1 180 1 450 on minimum Brinellhardness of 160.

Not advised unlessChilledCast Iron 650 1 100 1 325 1 550 715 1 210 1 450 1 780 surface is uniformin hardness.

Grooves must be groundManganese Steel 1 470 2 400 3 000 3 500 1 650 2 750 3 300 4 000 and sheaves balancedfor high-speed service.


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Values for the allowable unit radial pressures given in Table 8 are intendedsolely as a user s guide. And use of these figures does not guarantee preventionof any trouble. Further, the values should not be taken s restrictive with regardother or new materials. There are, for example, certain elastomers in currentuse that are apparently providing excellent service, but since there is insufficiendata to support specific recommendations, such products are not mentioned.BENDING WIRE ROPE OVER SHEAVES AND DRUMSSheaves, drums and rollers must be oia correct design if optimum service isto be obtained from both the equipment and the wire rope. Because there are mdifferent types of equipment and many different operating conditions, it is

difficult to identify the one specific size of sheave or drum most economicalfor every application.The rule to follow is this: the most economical design is the one that mostclosely accommodates the limiting factors imposed by the operating conditionsand the manufacturer s recommendations.All wire ropes operatingover sheaves and drums are subjected to cyclicbending stresses, hence the rope wires will eventually fatigue. The magnitude othese stresses depends all other factors being constant uponthe.ratioofthe diameter oithesheaveor drum to the diameter of the rope. Frequently,fatigue from cyclic, high-magnitude bending stress is the principalEeason forshortened rope service.

To illustrate, in order to bend around a sheave, the rope s strands and wiremust move relative to one another. This movement compensates for thedifference in diameter between the underside and the top side ofthe rope, thedistance being greater along the top side than is on the underside next tothe groove. Proper rope action and service) is adversely affected if shifting thewires cannot compensate for this situation. Also, there can be additionalmotion retardation because of excessive pressure caused by a sheave whose grodiameter is too small, or by a lack of lubrication. Changing the bending directionfrom one sheave to another should be scrupulously avoided as this reversebending still further accelerates wire fatigue.The relationship between sheave diameter and rope diameter is a criticalfactor that is used to establish the rope s fatigue resistance or relative service lifIt is expressed in the tread D/d ratio mentioned earlier in which D is the treaddiameter of the sheave and d is the diameter of the rope. Table 9 lists suggesand minimum values for this ratio for various rope constructions. Tables 10and show the effect of rope constructions and D/d ratios on service life.

39


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TABLE 9 ,RE OMMENDED SHE VE ND DRUM R TIOS

Suggested MinimumConstruction D d ratio D d ratio6x 7 72 4219 x 7 or 18 x 7 51 346 x 19 Seale 51 346x25B 45 306x27H 45 306x30G 45 306 x 21 filler wire 45 306 x 25 filler wire 39 266 x 31 Warrington Seale 39 266 x 36 Warrington Seale 35 238 x 19 Seale 41 278 x 25 filler wire 32 216 x 41 Warrington Seale 32 216 x 42 Tiller 21 14

*D =tread diameter of sheave d =nominal diameter of ropeTo find any recommended or minimum sheave tread diameterfrom the above table, the ratio for the construction rope tobe used is multiplied by its nominal diameter d . For example:The minimum sheave tread diameter for a Y2 6 x 21 FW ropewould be inch nominal diameter x 3 minimum ratioOr 15 inches.Note: These values are for reasonable service. Other, different.values are permitted by various standards such as ANSI.API, PCSA, etc. Smaller valuesmean shorter life.

4


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TABLE 10R L TIV BENDINGLIFE ~ T O R S

RopeConstruction6x718 x 76 x 19 S6 x 30 Style G6 x 25 Style B6 x 21 FW6x25FW

Factor.57.67.80.80.80.92

1.00

RopeConstruction

6 x 31 WS6 x 36 WS8 x 25 FW6 x 41 SFW6 x 43 FWS6 x 49 SWS6 x 42 Tiller

Fac1.01.31.31.31.51.52.0

If a change in construction is being considered as a means of obtaining longer service on a ropinfluenced principally by bending stresses. the table of factors may be useful. For example: achange from a 6 x 25 FW with a factor of 1 00 to a 6 x 36 WS with a factor of 1 31 would mthe service life could be expected to increase 1 31 times or 31 It must be pointed out however that these factors apply only for bending stresses. Other factorwhich may contribute to rope deterioration have not been considered.

. SERVICE LIFE CURVE FOR VARIOUS Old RATIOS

I I I I i I /I i 1 I I I I I I I I I i I i I iI I I I I j i /I iI I I / i I i / i

I i / /1 ii / I / ;1 ii I

i I ..v I I i iFigure 28. This servi e life urve only takesinto account bending and tensile stresses. Itsapplicability can be illustrated by thefollowing example: A rope working witha i ratio of 26 has a relat ive service l ifeof 17. I f the same rope works over a sheavethat increases its i ratio to 35 the r l t i v ~service life increases to 32. In short thisrope used on a larger sheave increases itsservice life from 17 to 32--or 88 .

1

90

eo70wu

wu 60>a:wIIwQ..oa:w> 40iJa: 3

20

10

41

10 20 3Old RATIO

40 50 60


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Figure 29. Cross-sections illustrating 3sheave-groove conditions revealed by themetric arrangement of wires in the strand.tight; and C is too loose.

B

B

c

c

INSPE TION OF SHE VES ND DRUMSUnder normalconditions, machines receive periodic inspections, and their over-allcondition is recorded. Such inspections u s u ~ l l y include the drum, sheaves, andany other parts that may come into contact with the wire rope and sUbject towear. As an additional precaution, rope-related working parts, particularly in theareas described below, should be re-inspected prior to the installation of anew wire rope.The very first item to be checked when examining sheaves, rollers and drums,is the condition of the grooves Figs. 29 30 and 31 . To check the size, contourand amount ofwear, a groove g g is used. As shown in Figure 29, the gageshould contact the groove for about 150 0 of arc.

. Two types of groove gages are in general use and it is important to notewhich of these is being used. The two differ by their respective percentageover nomin l

Fo r new or re-machined grooves, the groove gage is nominal plus the fulloversize percentage. The gage carried by most wire rope representatives today isused for worn grooves and is made nominal plus the oversize percentage.

This latter gage is intended to act as a sort of no-go gage. Any sheave with groove smaller than this u t be re-grooved or, in all likelihood, the existingropewill be damaged.When the sheave is re-grooved it should be machined to the dimensions fornew andmachined grooves given inTable 11. This table lists the requirements fornew or re-machined grooves, giving the groove gage diameter in terms of the

nominal wire rope diameter plus a percentage thereof. Similarly; the size of theno-go gage is given, against which worn grooves are judged. Experiencehas clearly demonstrated that the service life of the wire rope will be materiallyincreased by strict adherence to these standards.

o

Figure 30. Th.ese sheave-groove crosssections represent 3 wire rope seatingconditions: A. a new rope in a new groove;B a new rope in a worngroo e ; and C. aworn rope in a worn groove. See also Figs;29 and 31.)

GROOVG G

Figure 31. 11Iustrating the various dimensions of a s ~ ~ v e and the lise of ~ r o o v e gage.4


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TABLE 11MINIMUMSHEAVE- AND DRUM-GROOVE DlMENSIONS*Nominal Groove Radius

Rope Diameter New Worn1 2 3 4 5 6inches mm inches mm inches mm

;I ; 6.5 .137 3.48 29 3. 16 8.0 .167 4.24 .160 4. 9.5 .201 5.11 .190 4.i J.6 .234 5.94 .220 5.h 13 .271 6.88 .256 6.

14.5 .303 7.70 .288 7. 16 .334 8.48 .320 8.34 9 .401 10.19 .380 9. 22 .468 11.89 .440 111 26 .543 13.79 .513 13.

l 29 .605 15.37 .577 14 ; ; 32 .669 16.99 .639 161 35 .736 18.69 .699 17.1 h 38 .803 20.40 .759 19.1 42 .876 22.25 .833 21. 34 45 .939 23.85 .897 22.IV 48 1.003 25.48 .959 24.2 5 1.070 27.18 1.019 25.2;.s 54 1.137 28.88 1.079 27.2; ; 58 1.210 30.73 1.153 29.2 6 1.273 32.33 1.217 30.2lh 64 2.338 33.99 1.279 32.2 67 1.404 35.66 1.339 34.234 7 1.481 37.62 1.409 352 74 1.544 39.22 1.473 37.3 77 1.607 40.82 1.538 39.3;.s 80 1.664 42.27 1.598 40.31,4 83 1.731 43.97 1.658 42.3 87 1.807 45.90 1.730 43.

*Values given are applicable to grooves in h 90 1.869 47.47 1.794 45.sheaves and drums: they are not general1ysuitable fo r pitch design since this may 334 96 1.997 50.72 1.918 48involve other factors. 4 103 2.139 54.33 2.050 52.Further. the dimensions do not apply to 4; ; 109 2.264 57.51 2.178 55.traction-type elevators: in this circumstance. h 115 2.396 60.86 2.298 58.drum- and sheave-groove tolerances should 434 122 2.534 64.36 2.434 61conform to the elevator manufacturer'sspecifications. 67.64 2.557 64.128 2.663Modern drum design embraces extensive 51,4 135 2.804 71.22 . 2.691 68.considerations heyond the scope of this 5lh 4 2.929 74.40 2.817 71puhlication. should also be noted tha tdrum grooves are now produced with a 534 148 3.074 78.08 2.947 74number of oversize dimensions and pitches 6 154 3.198 81.24 3.075 78applicable to certain service re quirements.

43


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THE XCHART -ABRASION RESISTANCEVS. BENDINGFATIGUE RESISTANCEWhile there is a possibility, there is little likelihood that an application can befound for which there is a precisely suitable wire rope--one that can satisfyevery indicated requirement.

As with all engineering design probll::ms, feasible solutions demandcompromise to some degree. At times, it becomes necessary to settle for less thanoptimum resistance to abrasion in order to obtain maximum flexibility; thelatter being a more important requirement for the given job. A typical example ofthis kind of trade-off would be in selecting a highly flexible rope on an overheadcrane. Conversely, in a haulage installation, a rope with greater resistance toabrasion would be chosen despite the fact that such ropes are markedlyless flexible.Two compelling factors that govern most decisions as to the selection of awire rope are: abrasion resistance and resistance to bending fatigue. Strikinga proper balance with respect to these two important characteristics demandsjudgment of a very high order . A graphic presentat ion of just such comparison ofqualities between the most widely used rope constructions and others is givenby means of the X chart Fig. 32).

Referring to this chart when selecting a rope, the mid-point (a t the X)comes closest to an even balance between abrasion resistance and resistance tobending fatigue. Reading up or down along either leg of the X, the inverserelationship becomes more apparent as one quality increases and the otherdecreases.

Fijture 32. The wire rope inuusth refers tothis as the X chl/rl. It servesto illustr:ite theinverse relationship hetween ahrasionresistance :md resistance to henuing fatigue ina representative numher of the most widelylIszJ ....ire ropes.

o 6z014

o. 0:: 16WOJ:20::::>Z 18

44

< ~ e,_U >- tv_~ ~ .,, V~U U1-0 . ,0e, /: t


45/128

The term flexibility is frequently thought of as being synonymous withresistance to bending fatigue This is not true. Flexibility refers to the capabilityflexing or bending While a high degreeof fatigue resistance may sometimesaccompany the flexibility characteristic, it does not necessarily follow that this isA fiber core rope, for example, is more flexible than an IWRC rope. Yet, whenthe IWRC rope is bent around undersize sheaves at relatively high loads, it wiusually perform better than the more flexible fiber core rope. The reason forthis lies in th ability of IWRC rope to retain its roundness and freedom of internmovement. Under the same conditions, a fiber core rope will flatten andinhibit free internal adjustment, thereby leading to early failure.

As noted earlier, a design choice is almost invariably the result of compromUltimately, what issought is an efficient, economical solution, hence whateverthe compromise, it must helpachieve this goal.RE KING IN NEW WIRE ROPEA new wire rope requires careful installation and close adherence to followingall the appropriate procedures previously noted. After the rope has been.. instaand the ends secured in the correct manner, the mechanism should be startedcarefully and then permitted to run through a cycle of operation at very slowspeed. During this trial operation, a very close watch should be kept on allworking parts sheaves drums, rollers to make certa in that the rope Junsfreely, and without any possible obstructions as it makes its way through thesystem. no problems appear in running the rope, the next step should includeseveral run-throughs of the normal operational cycle under light load and a treduced speed. This procedure allows the component parts of the new rope to ma gradual adjustment to the actual operating conditions.WIRE ROPE ND OPER TIONS INSPECTIONTo assure a high level of safety while keeping the annual cost of wire rope at areasonably low level, it is essential to maintain a well-planned program ofperiodic inspection. Frequently, there are statutory and/ or regulatory agencieswhose requirements must be adhered to, but whether or not these exist in a gilocale, the wire rope user can be guided by the suggested procedures that follow.

A brasion bending an d crushing represent the ABC s ofwire rope abuse,.and iUs the primary goal of good inspection practice to discover such conditionsearly enough so that corrections can be made or ropes replaced safely andwith minimum effort. When any degradation indicates a loss of original ropestrength, a decision must be made quickly as to allowing the rope to remain inservice. But such a decision can only be made by an experienced inspector.And his determination will be based_on: I.) Details ofthe equipment s operaTion: Will the rope break?2 Frequency of inspection: Will it be safe until the next scheduled inspection?3 Maintenance history: How rapid is the degradation?4 Consequences of failure: Will it present hazards to humans?5 Historical records of similar equipment

To make certain that sufficient information is obtained. following areguidelines. that should be adhered to:45


46/128

the fleet angle Fig. 34) is large, it may be necessary to accept a smallerarc of contact at the throat; 1300 for exa.mple instead of 1500. This is doneto avoid scrubbing the rope on the flange of the sheave.As previously noted, the groove size is evaluated on the basis of how thegage leaf fits the groove. Daylight under the gage is not tolerable when using theworn groove gage. a full over-size gage is used, some daylight may be acceptable,but this really must be judged by relating the measurement to the ctu lsizeof the rope.

For new rope, extra caution should be observed s to its fit in the groove.Characteristically, ropes become smaller in diameter immediately after beingplaced in service. As a result, they would operate satisfactorily in a worng r o o v ~ cine thatwas gaged OK by the worn groove gage. Nonetheless, in somecases, a rope may not pull down, and if this happens, abnormal wear may occur.

t is important to remember that a tight groove not only pinches anddamages the rope but that the pinching prevents the necessary adjustment ofthewires and strands. On the other hand, a groove that is too large will notprovide sufficient support; in this case, the rope will flatten and thereby restrictthe free sliding action cif the wires and strands.

The size of the groove is not the only critical item to be examined closely.The condition of the groove is also an important factor of concern. Is it smooth orimprinted? the groove is imprinted then it must be re-machined or, if it isimprinted too deeply, it means that sheave, roller or drum must be replaced. replacement is indicated, a larger sheave or drum should be installed ifpossible, or a harder material should be specified for the replacement.

Groove examination should also concern itself with how the groove is we ringit is worn off-center, thereby forcing the rope to undercut or to rub againstthe flange, it then becomes necessary to correct the alignment of the reevingsystem, and to specify a harder material.

When checking the grooves, the bearings of the sheaves and rollers shouldalso be examined. They should turn easily. not, each bearing must be properlylubricated. Wobble in the sheave-from broken or worn bearings-is notacceptable. Bad bearings will set up vibrations in the wire rope that can causerapid deterioration unless the condition is remedied. Bad bearings also increasethe force on the rope that is needed to move a given load, since frictionforces will be greatly increased.

Sheaves with broken flanges may allow the rope to jump from the sheaveand become fouled in the machinery. When this happens, the rope is cut;curled, and the crowns of the wires in the strands are burred. There is ampleevidence to support then.lle that shea.ves with broken flanges must bereplaced immediately.

A sheave or drumwitha flat spot can induce a Whip into the line. This\vhip. or wave. travels until it is stopped by the end terminal, at which point the ropemay bend severely. This condition helps to accelerate the fatigue breakageof wires. Sometimes the reeving is such that the whip or wave is arrested by asheave. or the drum itself. In these circumstances. the whipping will causewire breaks along the crowns of the strands. Obviously, sheaves or drums thatex ite vibrations of this sort, must repaired or replaced.46


47/128

In addition to the items listed above. inspection should also focus on any aall conditions that could cause wear and eventual damage to the wire rope.

For example, plain-face (smooth) drums can develop grooves or ropeimpressions that will prevent the rope from winding properly. Imprinting is. greatest at the pickup point when the machine is accelerating. this happens,the surface should be repaired by machining or replaced. The winding should bchecked to make sure that the rope is winding threadwound (Fig. 27).

Excessive wear in grooved drums should be checked for variations eitherin the depth or pitch of the grooves. This condition is particularly criticalwhen double drums are used because a differential force will be set up that canbreak the drum and shear the shaft.

No matter what type of drum is in use, excessive drum wear will usually resin rapid rope deterioration, This conditionwill accelerate rapidly when windingin multiple layers.STRENGTH LOSS OF WIRE ROPE OVERSTATIONARY SHEAVES OR PINSRope breaking strength is determined in a standard test wherein fittings areattached to the ends of the rope and the rope is pulled in a straight line.

If however, the rope passes over acurved surface (such asa sheave or pinits strength is decreased. The amount of such reduction will depend on theseverity of the bend as expressed by the i ratio. For example, a rope bentaround a pin of its own diameter will have only 50 of the strength attributed tit in the standard test. This is called 50 efficiency (Fig. 33) . Even ati ratios of 40, there may be a loss ofup to 5% . At smaller i ratios, theloss in strength increases quite rapidly.

The angle of bend need no t be I 80 0 90 0 , or even 45 0 ; relativelysmall bends can cause considerable loss.

All discussion of strength pre-supposes a gradually applied load notin excess of 1 /minute.

384066 22Ol d RATIO

14

I I II I i II I i I I I I i I I i iI Ii\J I I I i I i II I I

I \ I I i I I i I I 1 I II N.. I i I 1 : i I i I II i j I I II I [ : : i I I I I I I I I I I I 1 I ; i I i i i i i I I I j i i I I II 1 i I i I I90100

60

EFFICIENCY OF WIRE ROPE WHEN BENT OVER SHE VES PINS OF VARIOUS SIZES50

70zU60

F igur e33. Der ived from standard test data.this curve relates rope strength efficiency tovarious i ratios. The curve is based onstatic loads only and applies to 6 x 19 and6 x 17 class ropes.

47


48/128

FIXEDSHEAVE

II1 \ \I \ \ \I \

I \ r FLOATINGI ,- - -SHEAVE rI \I \I \I \ \I \ \I \ \

I \I \I \I \I \ 1 2 MIN IlZoMiN \11i 2MAX IIIZOMAX \.... 0;I LEFT RIGHT \I FLEET FLEET \I ANGLE ANGLE \

Figure 34. This illustration of wire roperunning from a fixed sheave. over a floatingsheave. and then oil to n smooth drum.graphically defines the f 1 ( I I I / I I ~ ~ h

FL T NGLThe achievement of even windirigorta smooth faced drum is closely relatedto the ma.gnitude ofthe D/ d ratio the speed of rotation load on the rope and thefleet angle. Of all these factors the one that exerts perhaps the greatestinfluence on winding characteristics. is the fleet angle.

The schematic drawing Fig. 34) shows an installation where the wirerope runs from a fixed sheave. over a floating sheave. and then on to the surfaceof a smooth drum. The fleet angle Fig. 34) may be defined as the includedangle between two lines; one line drawn through the middle of the fixed sheaveand the drum-and perpendicular to the axis of the drum and a second line drawnfrom the flange of the drum to the base of the groove in the sheave.The drum flange represents the farthest position to which the rope can travelacross the drum.) There are left and right fleet angles. measured to the leftor right of the center line of the sheave respectively.

It is necessary to restrict the fleet angle on installations where wire ropepasses over the lead or fixed sheave and onto a drum. For optimum efficiencyand service characteristics. the angle here should not exceed 11/2 for a smoothdrum nor 2for a grooved drum. Fleet angles larger than these suggestedlimits can cause such problems as bad winding on smooth drums and the roperubbing against the flanges of the sheave grooves. Larger angles also createsituations where there is excessive crushing and abrasion of the rope on the drum.Conversely small fleet angles-less than lh o-should also be avoided sincetoo small an angle will cause the rope to pile up.


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F TORS FFE TING THE SELE TION OF WIRE ROPEThe key to choosing the rope best suited for the job, lies n an accurate estimatioof the important requirements. Correct appraisal of the following will simplifythe selection process:

Strength resistance to breaking2 Resistance to bending fatigue3 Resistance vibrational fatigue4 Resistance to abrasion5 Resistance to crushing6 Reserve strengthIt s well-nigh impossible for any single rope to have top values in all of the

above qualities. The rule, in fact, seems to be that a high rating in one almost_always means lower ratings in others. The first task s to make a careful analysisthe job requirements, establishing priorities among these requirements, andthen selecting the rope on a trade-off basis. This will provide the best possiblebalance y sacrificing the least essential advantages in order to obtainmaximumbenefits in the most important requirements.

Following, are brief explanations ofthe six factors previously listed: Strength resistance to breaking

As has been noted at the veryoutset. a wire rope s a machine-a fairly, compdeviCe that transmits and modifies force and motion. Thus, the very firstconsideration in choosing a machine, is to determine the potential workload. Stated in tenus of wire rope, this means establishing the actual16adthat s to be moved. To this known dead weight, there must be added thoseloads that are caused by abrupt starts acceleration), sudden stops,shock loads, high speeds, friction of sheave.bearings. Another item in thisequation is the loss of efficiency that occurs when the rope is bent oversheaves. All of these loads must be summed up in order to determine the truetotal load that w ll ultimately be handled.

For an average operation, this figure is generaliy multiplied by a desigfactor of 5. For increased mobility or design space economy, a designfactor of less than 5 s used at times. but i f the load s especially valuable,or if there s danger to human life, a larger design factor up to 8 or 9) s usein some instances. A still larger factor s sometimes found to be desirable.The factored load s now used to choose the size, grade, and core of the wirerope to be considered. An extended discussion of Design Factors can befound on page 76.)2 Resistance to bending fatigueTo describe this, a close analogy can be made with a paper clip. i t isrepeatedly bent back and forth at one point. it will eventually break. The reafor this s a phenomenon called metal fatigue. To some degree, the samething happens when a wire rope s bent around sheaves. drums, and rollers,The sharper-or more acute-the bend. the quicker the fatigue factordoes its work. Accelerating the rate of travel also speeds up fatigue; closecoupled re\ erse bending will speed it up at an even greater rate.

But fatigue can be greatly reduced if sheaves and drums have, at the49


50/128

very least, the recommended minimum diameter (Table 9 As for the rope,there is one governing overall rule: the greater the number of wires in eachstrand, the greater the resistance of the rope to bending fatigue.

The subject of metal fatigue is covered by a large and extensive body ofliterature. is not the intent of this publication to discuss, even in broadterms, the theoretical concepts of the phenomenon. will simply be notedhere that the concept of fatigue as a cause of metal crystallization isincorrect since all metals are at all times crystalline in structure. The crystallineappearancein many fractures is not indicative of crystallization.Resistance to vibrational fatigueVibration, from whatever source, sends shock waves through the rope. Thesewaves are a form of energy that must be absorbed at some point. This pointmay appear at various places- -the end attachment, the tangent where the ropecontacts the sheave, or at any other place where the waves are arrested andthe energy absorbed.

In the normal operation of a machine or hoist, wire ropes develop aWave action that can be observed either as a low frequency or as a sharp, highfrequency cycle. A good example of this is found in shaft hoists. When thecage is just starting up, the rope has a very slow swing within the shaft. But,by the time the cage reaches the t

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