Configuracion grua

8/3/2019 Configuracion grua

http://slidepdf.com/reader/full/configuracion-grua 1/22

Principles

With every building machine the manufacturer submits a machine technical document

the runner. In the business and maintenance instructions contained in this are gone int

right choice, maintenance and control at corresponding machines also deep by steel wire

and e.g. the professional procedures are also desrcibed at the rope change. In the end, is

spare part list called the manufacturer specific or objective ordering names of the steelcables perhaps to be obtained newly detailedly and clearly.

For steel wire-cables wire

The high function value of the steel wire-cables into building machines justifies the acq

of the DIN paperback no. 59 in which the most essential norms are collected about wire-

DIN 2078, sheet1, gives a survey of the diameters and as well as which of specific lengt

of the steel wires normally used for steel wire-cables. The mechanical material knowing

of the steel wires are in DIN 2078, sheet 2, represented for wire-cables and the test proce

continuation.

Wire is predominantly used for steel wire-cables to the equipment of building machines

calling tensile strength of 180 DaN/mm ². E.g. one takes wire away from the calling testrength 200 DaN/mm ² while for elevator ropes wire qualities with calling tensile stre

results of 140 and 160 of DaN/mm ² are usual for from putting pure moving ropes for

vehicle crane.

Verse rushing manners



The DIN 3051 informs about the systematics of the different rope manners in two sheet

law-and left-handed braid twisting is marked by lower case letters: Right-handed "z";

handed "s".

Choice and order

At the order of steel wire-cables for building machines, in principle, the details th

corresponding spare part list should be followed for the already known reasons. If the ne

wire-cable is then ordered from the machine manufacturer or from the storekeepers di

then the detail of the respective spare part number suffices for the clear rope identific

generally. If one votes for another rope supplier, then this needs at least hereinafter de

° of use of the rope

° needed rope length (detail in m)

° of nominal diameter of the steel wire-cable (in mm)

° of construction or design of the steel wire-cable detail (of the corresponding DIN nu

° of manner of the desired rope deposits (short sign)

° of desired wire surface (short sign)

° of required calling strength of the steel wires (in N/mm ²)

° of use conditionally required (specified) blow manner and -- direction

° standard or tension poor execution (short sign)

ROPE SELECTION

Strands and Construction

Wires are the basic building blocks of wire rope. They lay around a "center" in a specifi

pattern in one or more layers to form a strand. The strands lay around a core to form a

rope. The strands provide all the tensile strength of a fiber core rope and over 90% of th

strength of a wire rope with an independent wire rope core.

http://www.whb-baumaschinen.com/ENGLISH/SERVICE_e/Maintance_Service/body_steel_wire_ropes.html#choise&order





Characteristics like fatigue resistance and resistance to abrasion are directly affected by

design of strands. In most strands with two or more layers of wires, inner layers support

layers in such a manner that all wires may slide and adjust freely when the rope bends.

general rule, a rope that has strands made up of a few large wires will be more abrasion

resistant and less fatigue resistant than a rope of the same size made up of strands with

smaller wires.

Preformed Special Rope with Plastic Material

P 825 ropes can be used universally, where a non-rotating rope

required !

- high resistance to reverse bending stress

- less waer inside the rope

- completely tension-free rope structure

- hardly affected by vibrations

-

Leading cranes manufactures believe in the rope P825 !

Basic Types of Wire Ropes

Bright Wire. Most ropes are made with an uncoated (bright) wire that is manufactured from

carbon steel. The chemistry of the steel used and the practice involved in drawing the wire are

to supply the ultimate combination of tensile strength, fatigue resistance, and wear resistancefinished rope.

Galvanized wire. This is often used to improve corrosion resistance of wire ropes. We use th



following two different procedures to manufacture galvanized wire:

Galvanized to finished size wire is first drawn as a bright wire to a predetermined size t

smaller than the required finished wire size. This wire is then run through the galvaniziand the resultant coating of zinc increases the wire diameter to the finished size. Galvan

finished size wire has a strength 10% lower than the same size and type of bright wire.

made from this wire therefore have a nominal strength that's 10% lower than the equivasize and grade of bright rope.

Drawn galvanized wire is galvanized before the final drawing to finished size. Since thgalvanized coating also goes through the drawing process, it is much thinner than the c

on galvanized to finished size wire. Drawn galvanized wires are equal in strength to the

size and type of bright wire and drawn galvanized rope is equal in strength to the sameand grade of bright rope.

Galvanized aircraft wire. A galvanized wire that has higher tensile strength and fatigue resisIts primary usage is in aircraft control cables.

Stainless steel wire. This is a special alloy containing approximately 18% chromium and 8%It has high resistance to many corrosive conditions and is used extensively in yachting ropes acontrol cables.

"Lay" and Rope Design

"Lay" has three meanings in rope design. The first two meanings are descriptive of the wir

strand positions in the rope. The third meaning is a length measurement used in manufacturiinspection.

The direction strands lay in the rope -- right or left. When you look down a rope, strandright lay rope go away from you to the right. Left lay is the opposite. (It doesn't matter

direction you look.) The relationship between the direction strands lay in the rope and the direction wires la

strands. In appearance, wires in regular lay run straight down the length of the rope, anlang lay, they appear to angle across the rope. In regular lay, wires are laid in the strandopposite the direction the strands lay in the rope. In lang lay, the wires are laid the same

direction in the strand as the strands lay in the rope. The length along the rope that a strand makes one complete spiral around the rope core.

is a measurement frequently used in wire rope inspection. Standards and regulations re

removal when a certain number of broken wires per rope lay are found.

The lay of a rope affects its operational characteristics. Regular lay is more stable and more reto crushing than lang lay. While lang lay is more fatigue resistant and abrasion resistant, use is

normally limited to single layer spooling and when the rope and load are restrained from rotati

Preforming



Preforming preshapes strands before the rope is closed. This process helically shapes the wire

strands into the shape they will assume in the finished rope. It improves handling and resistanckinking by conforming the strands to the position they take in the rope.

The superior qualities of preformed ropes result from wires and strands being "at rest" in the r

which minimizes internal stresses within the rope. Today, preforming is virtually standard in r

manufacture, and non-preformed rope is made only on special order.

Choosing the Right Wire Rope

All wire ropes feature design characteristic tradeoffs. In most cases, a wire rope cannot increasfatigue resistance and abrasion resistance. For example, when you increase fatigue resistance

selecting a rope with more wires, the rope will have less abrasion resistance because of its gre

number of smaller outer wires.

When you need wire rope with greater abrasion resistance, one choice is a rope with fewer (an

larger) outer wires to reduce the effects of surface wear. But that means the rope's fatigue resis

will decrease. That's why you need to choose your wire rope like you would any other machincarefully. You must consider all operating conditions and rope characteristics.

Strength. Wire rope strength is usually measured in tons of 2,000 Ibs. In published mat

wire rope strength is shown as "nominal" strength. Nominal strength refers to calculatestrength figures that have been accepted by the wire rope industry.

When placed under tension on a test device, a new rope should break at a figure equal t

higher than -- the nominal strength shown for that rope. The nominal strength applies to new, unused rope. A rope should never operate at -- or

the nominal strength. During its useful life, a rope loses strength gradually due to natur

causes such as surface wear and metal fatigue. Fatigue resistance. Fatigue resistance involves metal fatigue of the wires that make up

To have high fatigue resistance, wires must be capable "squared" ends are typical of fat

breaks. of bending repeatedly under stress -- for example, a rope passing over a sheave.

Increased fatigue resistance is achieved in a rope design by using a large number of wir

general, a rope made of many wires will have greater fatigue resistance than a same-sizmade of fewer, larger wires because smaller wires have greater ability to bend as the ro

passes over sheaves or around drums. To overcome the effects of fatigue, ropes must nebend over sheaves or drums with a diameter so small as to bend wires excessively. Theprecise recommendations for sheave and drum sizes to properly accommodate all sizestypes of ropes.

Every rope is subject to metal fatigue from bending stress while in operation, and theref

rope's strength gradually diminishes as the rope is used. Crushing resistance. Crushing is the effect of external pressure on a rope, which dama

by distorting the cross-section shape of the rope, its strands or core or all three. Crushing resistance therefore is a rope's ability to withstand or resist external forces, an

term generally used to express comparison between ropes. When a rope is damaged by crushing, the wires, strands and core are prevented from m



and adjusting normally during operation.

In general, IWRC ropes are more crush resistant than fiber core ropes. Regular lay ropemore crush resistant than lang lay ropes. 6 strand ropes have greater crush resistance th

strand ropes or 19 strand ropes. Flex-X® ropes are more resistant than standard round-sropes.

Resistance to metal loss and deformation. Metal loss refers to the actual wearing away

metal from the outer wires of a rope, and metal deformation is the changing of the shap

outer wires of a rope. In general, resistance to metal loss by abrasion (usually called "abrasion resistance") ref

rope's ability to withstand metal being worn away along its exterior. This reduces strengrope.

The most common form of metal deformation is generally called "peening" - since outs

wires of a peened rope appear to have been "hammered" along their exposed surface. Pusually occurs on drums, caused by rope-to-rope contact during spooling of the rope on

drum. It may also occur on sheaves. Peening causes metal fatigue, which in turn may cause wire failure. The hammering --

causes the metal of the wire to flow into a new shape -- realigns the grain structure of t

metal, thereby affecting its fatigue resistance. The out-of-round shape also impairs wire

movement when the rope bends. Stability. The word "stability" is most often used to describe handling and working

characteristics of a rope. It is not a precise term since the idea expressed is to some degrmatter of opinion, and is more nearly a "personality" trait than any other rope feature.

For example, a rope is called stable when it spools smoothly on and off a drum -- or do

tend to tangle lay ropes, when a multi-part reeving system is relaxed. Strand and rope construction contribute mostly to stability. Preformed rope is usually m

stable than nonpreformed, and lang lay rope tends to be less stable than regular lay. A r

made of simple seven-wire strands will usually be more stable than a more complicatedconstruction with many wires per strand.

There is no specific measurement of rope stability. Bendability. Bendability relates to a rope's ability to bend easily in an are. The primary

that affect this capability are the diameters of wires that make up the rope, the rope and

construction, metal composition and finish, and the type of rope core. Some rope constructions are by nature more bendable than others. Small ropes are mor

bendable than big ones. Fiber core ropes bend more easily than comparable IWRC ropegeneral rule, ropes of many wires are more bendable than same-size ropes made with felarge wires.

Reserve strength. Reserve strength of a rope is that percentage of its catalog strength wrepresented by the inner wires of the outer strands. This recognizes that outer wires sho

the first to be damaged or worn away.

Usually, the more wires there are in each strand of rope, the greater will be its reserve stThis is true because of the geometry of a circle -- since increasing the number of outera strand also increases the cross-sectional area occupied by inner wires.

Rotation-resistant ropes, due to their construction, can experience different modes of w

failure than standard ropes. Therefore, their reserve strength is based on the percentagemetallic area represented by the core strand plus the inner wires of the strands of both t





Physical maintenance of the system in which your rope operates.

We've outlined several recommended practices you may use to extend your rope's useful life.

Install your rope correctly. T he primary concern when installing a new rope is to not trap a

in the rope system. Proper handling of the rope from the reel or coil to your equipment will heavoid this situation. Another important step on smooth faced drums is to spool with wraps tigh

close together on the first layer. This layer forms the foundation for succeeding layers. Finallythe remaining rope on the drum with tension approximating 1% to 2% of the rope's nominal st

Break in your new rope properly. When you install a new operating rope, you should first ra brief period of time with no load. Then, for best results, run it under controlled loads and spe

enable the wires and strands in the rope to adjust to themselves.

"Constructional" stretch.When first put into service, new ropes normally elongate while strgo through a process of seating with one another and with the rope core. This is called

"constructional" stretch because it is inherent in the construction of the rope, and the amount o

elongation may vary from one rope to another. For standard ropes, this stretch will be about 1/ 1% of the rope's length. When constructional stretch needs to be minimized, ropes may be fact

prestretched. Please specify when placing your order.

Another type of stretch, "elastic" stretch, results from recoverable deformation of the metal itsmore information, please refer to the WRCA Wire Rope Technical Data Handbook.

Cut off ends to move wear points. If you observe wear developing in a localized area, it maybeneficial to cut off short lengths of rope. This may require an original length slightly longer t

you normally use. When severe abrasion or numerous fatigue breaks occur near one end or atconcentrated area -- such as drag ropes on draglines or closing lines in clamshell buckets, forexample -- the movement of this worn section can prolong rope life.

Wire breaks from vibration fatigue occur at end terminations, so short lengths cut off there wit

reattachment of the socket may prolong the rope's life. When broken wires are found, you shooff sections of rope. In the case of a socket, you should cut off at least five or six feet. In the c

clips or clamps, you should cut off the entire length covered by them.

Where there is an equalizing sheave, such as that found in many overhead cranes, fatigue is loat rope tangency points to the equalizing sheave. Rope life will be increased if you shift this p

cutting off a short length at the end of one of the drums. Be sure to make this cutoff before sig

wear occurs at the equalizing sheave, and always do so at the same drum.

Reversing ends. Frequently, the most severe deterioration occurs at a point too far from the etoo long to allow the worn section to be cut off. In such cases, you may turn the rope end for ebring a less worn section into the area where conditions are most damaging. This practice is

beneficial for incline rope and draglines. The change must be made well before the wear reach

removal criteria. When changing ends, be careful to avoid kinking or otherwise damaging the



Lubrication . We lubricate our wire rope during manufacture so that the strands -- as well as t

individual wires in the strands -- may move and adjust as the rope moves and bends. But no wcan be lubricated sufficiently during manufacture to last its entire life. That's why it's importa

lubricate periodically throughout the life of the rope.

The surface of some ropes may become covered with dirt, rock dust or other material during t

operation. This can prevent field-applied lubricants from properly penetrating into the rope, sogood practice to clean these ropes before you lubricate them.

The lubricant you apply should be light-bodied enough to penetrate to the rope's core. You ca

normally apply lubricant by using one of three methods: drip it on rope, spray it on or brush itall cases, you should apply it at a place where the rope is bending such as around a sheave. Wrecommend you apply it at the top of the bend because that's where the rope's strands are spre

bending and more easily penetrated. In addition, there are pressure lubricators available

commercially. Your rope's service life will be directly proportional to the effectiveness of theyou use and the amount of lubricant that reaches the rope's working parts.

A proper lubricant must reduce friction, protect against corrosion and adhere to every wire. Italso be pliable and not crack or separate when cold yet not drip when warm. Never apply heav

grease to the rope because it can trap excessive grit, which can damage the rope. Nor should yapply used "engine oil" because it contains materials that can damage the rope. For unusual

conditions, you can specify special lubricants that we can apply at the factory.

Controls /Inspection



Because of of the high safety technical meaning already described at the beginning fu

safe ropes ropes moving must be checked in as short as possible time intervals. The re

have to be held tight in the control book. Rope control is among others also an importa

within the well-informed and (machine specifically specified) expert exams to buildimachines. Additional controls are required if was subject to the machines of unusual l

after longer no working was taken in operation again, has been used up dismantled on a

building site or is occurred after a damage or accident for the first time again. With sp

attention then have to be taken into account primarily those rope zones, about rolls w

move, are drummed on or mountings or fastenings are in which.

Inspection

All wire ropes will wear out eventually and gradually lose work capability throughout their se

life. That's why periodic inspections are critical. Applicable industry standards such as ASME

for overhead and gantry cranes or federal regulations such as OSHA refer to specific inspectiocriteria for varied applications.

Regular inspection of wire rope and equipment should be performed for three good reasons:

It reveals the rope's condition and indicates the need for replacement.

It can indicate if you're using the most suitable type of rope.

It makes possible the discovery and correction of faults in equipment or operation that c

cause costly accelerated rope wear.

All wire ropes should be thoroughly inspected at regular intervals. The longer it has been in s

or the more severe the service, the more thoroughly and frequently it should be inspected. Be smaintain records of each inspection.

Inspections should be carried out by a person who has learned through special training or pracexperience what to look for and who knows how to judge the importance of any abnormal con

they may discover. It is the inspector's responsibility to obtain and follow the proper inspectio

criteria for each application inspected.

What to Look For

Here's what happens when a wire breaks under tensile load exceeding its strength. It's typicall

recognized by the "cup and cone" appearance at the point of failure. The necking down of thethe point of failure to form the cup and cone indicates failure has occurred while the wire retai

ductility.



This is a wire with a distinct fatigue break. It's recognized by the square end perpendicular to t

wire. This break was produced by a torsion machine that's used to measure the ductility. This

similar to wire failures in the field caused by fatigue.

A wire rope that has been subjected to repeated bending over sheaves under normal loads. Th

results in fatigue breaks in individual wires -- these breaks are square and usually in the crownstrands.

An example of fatigue failure of a wire rope subjected to heavy loads over small sheaves. The

in the valleys of the strands are caused by "strand nicking." There may be crown breaks, too.

Here you see a single strand removed from a wire rope

subjected to "strand nicking." This condition is a result of adjacent

strands rubbing against one another. While this is normal in a rope'soperation, the nicking can be accentuated by high loads, small sheaves



loss of core support. The ultimate result will be individual wire break

the valleys of the strands.

Typical Evidence of Wear and Abuse

A "birdcage" is caused by sudden release of tension and the resulting reof rope. These strands and wires will not be returned to their original posThe rope should be replaced immediately.

A typical failure of a rotary drill line with a poor cutoff practice. Thesehave been subjected to continued peening, causing fatigue type failures. A predetermined, regscheduled cutoff practice can help eliminate this type of problem.

This is localized wear over an equalized sheave. The danger here is that it's invisible during t

rope's operation, and that's why you need to inspect this portion of an operating rope regularly.

rope should be pulled off the sheave during inspection and bent to check broken wires.

This is a wire rope with a high strand -- a condition in which one or strands are worn beforeadjoining strands. This is caused by improper socketing or seizing, kinks or dog-legs. At top,

a close-up of the concentration of wear. It recurs every sixth strand in a 6 strand rope.

A kinked wire rope is shown here. It's caused by pulling down a loop in

line during handling, installation or operation. Note the distortion of the strands and individual

This rope must be replaced.

Here's a wire rope that has jumped a sheave. The rope "curled"as it went

the edge of the sheave. When you study the wires, you'll see two types of here: tensile "cup and cone" breaks and sheat breaks that appear to have



cut on an angle.

Drum crushing is caused by small drums, high loads and multiple winding conditions.

Time of change

At all rope controls one should take into account and take therefore among others herein

criterions:

° of corrosion and Abrasion:>>> >>> The corrosion condition of the rope external surfaceschecked because ropes are with diameters reduced by corrosion opposite the nominal size ar

more as 10% to machines which are used or were in provably very aggressive air zones. On

rope sections the removal of the rope outside diameter has to be measured by structure changediameter removal exceeds 15% of the nominal size, the rope must be put down.

If the outside diameter of the rope is reduced by inside wear opposite the nominal diameter ar

least 10%, then the rope has to be put down.

° of wire breakages: The rope concentrated shows wire breakage nests or, even braid breaks, i

be put down immediately so. It is meaningful to pursue the development of wire breakages omachine use duration at definite rope checkpoints to close on the possible complete life time

rope and let corresponding orders of Vorlaufen from this.

The business instructions or the spare part list of the respective machine informs about the nof the load-bearing wires in the outer braids. One knows himself but the corresponding detai

pull out 3051 to 3072 of the DIN paperback 59 and the there contained DINs.

Removal Criteria

A major portion of any wire rope inspection is the detection of broken wires. The number andbroken wires are an indication of the rope's general condition and a benchmark for its replace

Frequent inspections and written records help determine the rate at which wires are breaking.

Valley wire breaks -- where the wire fractures between strands or a broken wire protrudes bet

strands -- are treated differently than those that occur on the outer surface of the rope. When t

more than one valley break, replace the rope.

Broken wire removal criteria cited in many standards and specifications, apply to wire ropes

operating on steel sheaves and drums. For wire ropes operating on sheaves and drums made w



material other than steel, please contact the sheave, drum or equipment manufacturer or a qual

person for proper broken wire removal criteria.

Guidelines for Installation and Maintenance

When you're installing wire rope, there's a primary concern: getting the rope on the equipmentwithout trapping any twist that may have been induced during handling or installation.

Here is the preferred technique for installing rope onto a crane:

Unload properly and relieve any twists. Pull the rope off the shipping reel or unroll it from

shipping coil as shown. (If done improperly, you may kink the rope, which will result in permdamage to the rope.) Then lay the rope on the ground in direct line with the boom. This helpsany twist in the rope.

Attach rope's end to drum. Pull the rope over the point sheave and attach the end to the druBefore making any end attachment, be sure the rope strands are free to adjust. (In other words,sure the end of the rope is not welded together.)

Wind rope onto drum slowly and carefully. At this point, it isn't necessary to provide additi

load other than the weight of the rope being pulled across the ground.

Spool first layer tightly. It's essential on smooth-faced drums that the first layer is spooled wi

wraps tight and close together since the first layer forms the foundation for succeeding layers.

be, use a rubber, lead or brass mallet (but never a steel hammer) to tap the rope in place.



Spool multiple layers with sufficient tension. It's very important to apply a tensioning load t

ropes during the rope breaking-in process. (If not, the lower layers may be loose enough that t

upper layers become wedged into the lower layers under load, which can seriously damage thThe tensioning load should range from 1 to 2% of the rope's nominal strength.

For ropes in multi-part systems: Peeve the traveling block and boomtip sheaves so the ropespacing is maximized and the traveling (hook) block hangs straight and level to help assure bl

stability. Avoid deadending the rope at the traveling block if possible.

Check rope for twist. With the rope slack, pull enough rope out to allow it to hang in a loop (



If the rope hangs without twisting together, there is no twist in the rope. If the rope twists toge

(left), the rope has twist in it. Follow steps to remove twist from the rope to make the most of service.

Breaking in your new wire rope. After installation, you should properly break in your rope,

allows the rope's component parts to adjust themselves to your operating conditions.

With the boom fully raised -- and fully extended if you're using a hydraulic boom -- attach a liload at the hook and raise it a few inches off the ground. Allow to stand for several minutes. Tcycle the load between the full "up" and "down" positions several times. Stand back and watc

drum winding and rope travel for any potential problems.

After making the lifts with a light load, increase the load and cycle it up and down a few times

procedure will train the rope and help assure smooth operation during its useful life.

Ideally, you should run these loads with reeving that lets you place the loads on the block withrope off the drum except the last three wraps. If this isn't possible, alternate methods must be

assure proper tensioning of the rope on the drum.

Always leave three wraps on drum. Although ANSI/ASME 830.5 states that two wraps mus

remain on the drum when the hook is in the extreme low position, we recommend at least threalways remain on the drum.

Rigging in tight quarters. If you can't lay the new rope out on the ground before rigging -- a

need to pull it directly from the reel further steps are necessary. First, you should mount the re

shaft through flange holes and on jack stands, making sure you spool as illustrated. Whileunspooling, do not allow the reel to "free-wheel." Brake the reel by applying pressure to a flan

Never apply braking pressure to the rope on the reel -- or pass the rope between blocks of wooother material.



Relieving twist. To relieve twist that may be trapped in a rope spooled directly off a reel to thraise the boom to its highest position while letting out the rope until the rope almost touches t

ground. Let the rope hang free without added load while standing clear. When twist is fully rel

proceed with rigging the crane.

Lubricate ropes often for long life. To properly maintain your rope, the first place to check i

obvious signs of abuse from other parts of the rope system. But the biggest part of maintenancinvolves regular lubrication to reduce friction between the rope's components as well as the fribetween rope and sheaves or drums.

Your rope receives internal lubricant at the factory, but it's not enough to last the rope's entire

to constant bending over sheaves and drums. The need to keep your ropes properly lubricatedemphasized enough.

Clean ropes first. Remove excess dirt, rock dust or other materials that can prevent field-appl

lubricants from properly penetrating into the ropes.

Lubricate using one of two methods: One is called manual lubrication such as spray or dripsystems that apply lubricant when you want. You can also swab or paint lube into your movin

by hand, or even pour lube onto your rope as it passes a certain point. The other is called autolubrication that drips or sprays lube onto your rope as it passes over a sheave at preselected int

What lubricant should you use? There are two lubricants you should not use. Never apply hgrease to the rope because it can trap excessive grit and dust, which can externally damage theor be forced inside, causing hidden damage. Nor should you apply used "engine oil" because it

contains materials that can damage your rope.

The kind and amount of lubricant will vary according to the type and use of your wire rope. Blubricant should have these traits:

Penetrate to the rope core. The best way is to apply at a place where the rope bends, sucover a sheave, exposing the wires and strands to provide a better opening to the core.

Contain enough adhesive and film strength to stick to wires in the rope and the spaces athe wires.



Be free of acids and alkalis.

Resist corrosion. Stay put without being easily washed away.

Drum Spooling: What to Do

When you're installing a new rope onto a crane, there's a primary objective: spool the rope ont

equipment tightly without trapping any twist in the rope on the drum. (See installation guidelidetails.)

For multiple-layer spooling, it's essential to get the first layers of rope tight with each wrap snagainst the preceding wrap. Since the first layer provides the "grooving" for upper layers, wra

be placed tightly together. If not, wraps in upper layers will pull down between wraps already

drum, which can cause crushing damage and reduced rope strength and service life.

When you encounter spooling problems, check the following list to identify the possible cause

of these are incorrect, the result can include open (or loose) spooling, random spooling or stac

rope against drum flanges.

Drum alignment. Before spooling, make sure the drum is level and at right angles to tboom. Many drums are mounted on the frame so that adjustment can be made in align

Drum winding. Wire rope should wind onto the smooth-faced drum as shown. Make swrap the rope left or right and over or under as recommended.

Use of a swivel. A swivel end termination will let the rope lay lengthen when loaded. A

rope spools onto a drum, the unlaid rope travels over the point sheave and accumulatesbetween the drum and point sheave. This leads to block rotation, erratic spooling, unbaland decreased rope service.

Fleet angle. One of the most important factors in proper winding of rope on drums. Forsmooth-faced drums, this angle should be between 1/2º and 1 1/2º. For grooved drums,should be between 1/2º and 23 Fleet angles larger than these can cause spooling proble

the rope to rub against the flanges of the sheave -- plus may lead to rope crushing and a

on the drum. Fleet angles smaller than these may cause the rope to pile up at the flanges

Point sheave. When more than one sheave is in use at the boomtip, make sure the leadpresents the optimum fleet angle to the drum.

Grooved drums. Groove spacing must be adequate to prevent the rope from crowdingadjacent wraps as the rope spools across the drum. In addition, groove spacing must notexcessive, which can allow wraps of the next layer to pull down between wraps of theprevious layer, causing abrasion and crushing.

Drum flanges. Flanges should be perpendicular to the drum face and not worn, deform

spread outward. These conditions can cause spooling problems at the change of-layer padditional layers are spooled.

Improper installation. When a rope has been installed in such a way that twist has beeintroduced into the rope, spooling problems can result. (See installation guidelines for d

Riser strips and kick plates. If spooling problems persist after you've considered the aconditions, try using riser strips and kick plates. For details on these accessories, check





Consider a 6-strand rope construction. Standard 6-strand regular lay ropes are less

susceptible to unbalance than other ropes. Remove any twist in rope. See rope installation guidelines for details.

Block Rotation

Also called cabling, block rotation occurs when multi-part reeving twists together at a certain

entangling the parts of rope between the traveling block and boomtip. It can happen with littlewarning, malting it virtually impossible to lift or lower a suspended load. Twisted hoist lines c

bring a construction project to a sudden halt, resulting in downtime.

But the good news is this. You can minimize block rotation through proper installation and ha

as well as take corrective measures if it occurs on your crane. The key is understanding torque

Every wire rope -- regardless of type, classification, grade or manufacturer -- will develop tor

when loaded.

Torque is normal and natural, caused by the way wire ropes are made. Wires are first laid togea spiral to form strands, then several strands are laid together in a spiral to form the rope. Whe

loaded, wires and strands try to straighten out, thus creating torque. Another source of torque ichange in the rope lay length. This is normally caused by "milking" or rotation at the end of th

Torque in a rope affects the tendency of the traveling block to rotate. Thus, it's important to many torque in your rope.

There are at least seven different operating practices you can use to minimize block rotation o

crane.



Change the rigging geometry. This includes the following operating practices: Use lar

diameter traveling block sheaves to increase the rope spacing (as the diameter of the trablock sheave increases, the chances for block rotation are reduced), use the outer (farth

apart) sheaves -- traveling block and boom, and dead-end the rope at the boomtip to incthe spread between the wire rope parts.

Use the shortest fall length possible. The length of fall, or the distance from the pick p

the point sheaves, is critical...longer fall lengths are less stable and more likely to lead t

rotation. Avoid odd-part reeving. An even number of parts is more stable.

Use taglines on lifts. Attach a tagline to restrain the load block and keep the load fromrotating.

Use a different rope construction. While there is no "right" or "wrong" wire rope to u

prevent block rotation, a rotation-resistant rope is your best choice due to its reduced toproduced under load. However, there may be a reduction in capacity with the same rigg

configuration due to different nominal strengths and the higher design factor required wusing rotation-resistant ropes.

Avoid using a swivel that allows the rope to rotate. A swivel in an end termination w

permit lay lengthening in the rope when loaded. While the lay only lengthens between t

swivel and the first sheave, the unlaid rope travels over the sheave as the load is lifted aintroduces unlaying to the section of the rope beyond the sheave. This unlaying become

trapped and will not come out of the rope when the load is removed. The trapped unlayicauses twist in the rope, which leads to block rotation, erratic spooling, unbalancing an

decreased rope service. Remove the swivel from the rope termination and follow steps t

remove twist from the rope to optimize rope service. Check sheave alignment and groove size. Improper sheave alignment or groove size

"milk" the lay in a rope and cause torque.

Four independent variables are used in pairs to locate a reference point on the graph that indicstability of the lift being made. The ratios used include:

L/S = Length of fall (ft.) + Spacing of the rope (ft.).

L = Length of fall measured from the centerline of the point sheave to the centerline of the tra

block sheave as shown in the diagram.

S = Average diagonal spacing of the rope at the boom point and the traveling block sheaves as

in the diagram.

D/d = (D) Average pitch diameter of point



For 2-part reeving, S = average pitch diameter of point and block sheave

For 3-part reeving, S = 2/3 of 2-part

For 4-part reeving, S = diagonal distance of rope parts

For 5-part reeving, S = 4/5 of 4-part

For 6-part reeving, S = diagonal distance of rope parts

For 7-part reeving, S = 6/7 of six-part system

When the reference point on the graph lies above the appropriate band, block rotation will probably occur. If the reference poin

below the band, then the lift will probably be stable without block rotation. If the point lies within the band, block rotation is un

Documents

Configuracion grua