why fm gru ce clasification

7/31/2019 Why FM Gru CE Clasification

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Service Life of CranesA Brief Explanation of the Basic TermsClassification of Cranes according to FEM 1.001

Prepared by : RAJEEV KUMAR (CEO DCS Crane Div)


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CE FEM 1.001 A4

Two crucial aspects need to bekept in mind when weighing upthe options before purchasingmaterial handling equipment,such as a Tower Crane: themaximum handling rates of thecrane and its total intendedduration of use (service life)Said by Rajeev Kumar (CEO Crane Div)

While great importance isattached to the maximumhandling rates in the decision topurchase, too little focus isplaced on an assessment of thecranes service life.

For this reason, the basicinterrelationships and factorsinfluencing the service life of aTower Crane are explained below.

What Do we Really Mean byService Life?

When a component or an entire unitsuch as a crane, is excessivelyoverloaded, it will fail at onceHowever, by far the more relevantcause of the damage is failure of thecrane due to use beyond its servicelife.

Each individual work cycle of acrane (even if the load lifted is farbelow the cranes maximum liftingcapacity) contributes to componenfatigue. If a load is applied oftenenough, the component fails even ifthe individual loads alone did nolead to the failure.

RAJEEV


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DCS is 14yearexperiencedorganiz

ation insales &

The Paper Clip Experiment

Take a paper clip in your hand and try totear it apart. It will not be possible. However,if you bend it back and forth several times,even a relatively small force is sufficient tobreak it. As a result of the repeated loading,the useful life of the paper clip is exceededbecause, as with most components intechnical applications, it was designed for a

finite service life that is not based on fatigueendurance.

With the help of this simple experiment it iseasy to understand that both the intensity ofthe stress (i.e. how powerfully the paper clipwas bent back and forth) and the number ofbends (work cycles) are relevant for thetime at which the failure occurs.

However, how would a paper clip made of

thicker wire behave? Experience fromeveryday life teaches us that it would havelasted longer. Another aspect for evaluatingthe service life is thus the durability (loadingcapacity) for which a component has beendesigned.

Two fundamental elements are decisive forevaluating the service life of a component ora crane: the load and the loading capacity.

The service life is a result of the interplay ofthese two components.

Effects of LoadingThe loads acting on a Tower Crane duringoperation are not constant. A distinction ismade between different modes of operation(heavy load operation, variable loadoperation, etc.), in which very different loadsoccur (still lifting concrete lifting, emptyload full load, etc.).

It is, therefore, not possible to assume aconstant load for the crane. As a result, thestandards according to which a crane isdesigned (e.g. FEM 1.001) define the loadingspectrum by means of which an attempt ismade to describe the actual load applied to acrane.

Given the same loads, anincrease in the crane group byone level (e.g. From A2 to A4)corresponds to a doubling ofthe expecteduseful life.


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How is a Loading SpectrumDetermined?

The standard on which the cranecalculation is based, i.e. FEM 1.001, makesit possible to estimate the future loading ofa crane and select one of four standardizedloading spectra. The standardized loadspectrum classes range from Q1 (cranepredominantly lifts low loads and only rarelymaximum permissible loads) to Q4 (cranefrequently lifts loads equal to its maximumlifting capacity). Therefore, the decisivefactor for selection of a spectrum class is

how frequently a crane has to lift heavyloads (in comparison to the maximum loadin the mode of operation examined).

Loading capacity

While loading is a characteristic of craneoperation, the loading capacity is acharacteristic of the crane construction.

When a crane is designed, a certain craneclassification is selected by themanufacturer and the crane is designedaccording to this classification.

FEM 1.001 offers a choice of eight groupclassifications (A1 to A8). In the exampleabove with the service life of a paper clip,we noted that the thickness of the wire is adetermining factor for the service life. In thesteel structure of a crane the same applies.

To put it in very simplified form: Thehigher the number of the crane group,the thicker the steel sheet and tubingused and the more robust the crane.


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Service

Life!If the loading capacity(crane group) and theexpected load (spectrumclass) are known, theservice life (class ofutilization) of the crane canbe determined on thatbasis.

According to FEM 1.001,this will give us a class ofutilization from U0 to U9and thus an indication ofhow many work cycles thecrane will manage beforethe end of its service life isreached. Towards the endof the service life, theprobability of failure

increases rapidly withfurther operation. Therelationship between thesizes, crane group,spectrum class andservice life is illustrated inBelow Figure and Table.If we now compare acrane in crane group A4 toa crane in crane group A2with regard to service life,

it is easy to determine onthe basis of the diagramhow long the useful life ofeach one will be.


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If both cranes are used for the same type of application, the same spectrum class applies to bothcranes. If this class is specified as Q3, it can be seen that the crane classified in A4 will have aservice life of more than 4,000,000 work cycles whereas the crane classified according to A2 wilreach the end of its service life after only 500,000 work cycles.

The crane with the higher classification thus has a useful life that is over four times longer given the

same loads! As a rule of thumb, one can state on the basis of the diagram in below Figure.

Cranes that have been classified in the highest crane group, A8, are designed such that the loads onthe components during operation are so low that theoretically no fatigue is caused by such operation.

Consequently, a crane classified in crane group A8 does not have a limited service life and will havean unlimited fatigue endurance.


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15 to 40 Meter Range (RBI Series)

The RBI Series cranes; a line of cranes of easy erection and simple usethanks to their handiness. The hydraulic erection is very quick and safeThe Steering axels with minimum radius of curvature allow the RBcranes to be positioned in narrow spaces. Thanks to the "self ballastingdevice" the crane can load the ballast by itself without the need of othermeans. The Simple and reliable mechanisms, controlled by a frequencyinverter, give smooth and fast movements, avoiding to overstress the

cranes structure. The RBI cranes, thanks to limited weights anddimensions, can be transported on trailers, keeping perfectly within thedimensional limits for road circulation.

30 to 80 Meter Range (TLX Series)

The TLX Series; a new line of crane that offers the best presenttechnology. The well proportioned, essential and stylish line, that showsthe basic parts of tower cranes, clearly remained that the "flat top"cranes aren't a "revolution" but an "evolution" of the product. The easyand quick erection is the main point that have impressed operators andtechnicians; it has been achieved a 20% reduction in erection times,

compared to previous cranes.

30 to 80 Meter Range (TCK Series)

The ideal line of cranes for your building yard. TCK series cranes aredesigned and manufactured to guarantee the highest safety standardsduring every assembling and working activity. The hinges coupling to thecenter plate allow the jib and counter-jib to mesh without dangerousadjustments being required. The lifting, slewing and distributionmechanisms are strong, simple and reliable. The modularity of itscomponents makes it extremely safe and easy to transport, by keepingthe required number of means of transport to a strict minimum.

36 to 80 Meter Range (LX Series)

These cranes have been designed for work on particularly high buildingsor in extremely restricted spaces. The luffing jib cranes are a goodexample of advanced technology and they are very fast to install. Thosecranes are conceived to solve all the problems that may appear inbuilding sites settled in crowded places, in the town centers or in someareas full of obstacles like prefabricated buildings or towers.

DCS Trading & Services Pvt Ltd.Our comprehensive service in tower crane runs from initial consultation to dismantling, andencompasses all aspects of crane management advice and site visits to determine exactlywhich cranes will best suit your requirements.


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FMgru Establish in Yr. 1926 is Worldleader in producing best in class towercrane. HIGH SAFETY: Safety has alwaysbeen the main objective of FMgru.Correct crane operation, the highestsafety for people and easy inspectionare the three aspects on which everysafety devices have been developed.The result has allowed us to offer qualityconstruction cranes that complies withthe main international directives (ISO,IEC, DIN, CNR, UNI, FEM).

DCS Trading & Services Pvt Ltd

AUTHORISE EXCUSIVE DISTRIBUTION & SERVICE PARTNER FOR INDIAHO : 169, Road No 11, Prashasan nagar, Jubilee Hills, Hyderabad. PIN : 500096

PH : +91-40-23558136, FAX : +91-40-23541134, Mobile : +91-8886886103Email : [email protected]

www.dcstrading.com

Our Regional & Sales offices:Bangalore, Chennai, Mumbai, Delhi, Kolkata, Patna & Trichy .

Ver : RK 1.2 A r12

STRONG DETAILS : Strong, sturdyand well sized mechanisms allow thestructural characteristics of a welldefined project to be used in the bestpossible way. Use of electronicequipment allows the crane driver toperfectly control the load.

FMgru engineers are able to designcranes according with your requirements

Fmgru construction cranes, based onstandard range but normally modifiedin many ways to suit the particularapplication and customerrequirements, different from case tocase, can be easily inserted in bothnew and already existing industrialplants and operating circles.
http://www.dcstrading.com/http://www.dcstrading.com/

why fm gru ce clasification

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