DN Staff

November 17, 2010

4 Min Read
Cable Carrier Extends Crane More Than a Quarter Mile

At the Lekir Bulk Terminal in Lumut, Malaysia (known for having the largestcapacity for bulk unloading goods in Southeast Asia), coal is unloaded fromships at docking stations on a man-made island by two large cranes built byGermany-based Koch, and then transported the 1.2 miles from the island to the TNB power station by conveyor belt. The cranes canunload up to 1,500 tons of coal per hour.

igus Malaysia Crane

igus Malaysia Crane

One of the two cranes at the Lekir Bulk Terminal in Malaysia equipped with igus cable carriers and cables for travel of up to 1,448 feet. Source: igus.


Koch and Siemens (which was responsible for the crane project's electricalengineering), worked in close cooperation with igus to specify a cable-carriersystem for the cranes with 1,448 feet of travel on each crane. According toigus, this application is one of the longest travels for a cable carrier in theworld.

An igusReadyChain, a pre-harnessed cable carrier, supplies energy and data to thetrolley and cabin in the cranes. A 732-foot cable carrier is used for thelongitudinal travel of each crane. Each cable carrier can accelerate up to 98 feetper minute and is filled with igus Chainflex cables, including CF-Crane, fiber-opticcables, and a water hose used to minimize the generation of dust whileunloading. This equals a fill weight of more than 4.7 pounds per foot. With across-travel cable carrier weight of more than 2.5 tons, the load is handledusing igus' Roll-E-Chain 5050R. This cable carrier's mini-integrated wheels aresaid to reduce shearing and traction loads by more than 75 percent due to thefriction coefficient.

Another igus cablecarrier (System E4/4) supplies the drivers' cabins on the cranes with a 240 foottravel distance and 2.8 pounds per foot load. The cable carrier is equippedwith specially designed Chainflex continuous-flex cables, which can travel atspeeds of 66 feet per minute and accelerate at 1.6 feet per second.

Environmental Factors
An importantfactor influencing the system design was the tropical climate in which thecranes operate, as temperatures fluctuate between 73 and 93 F with 77 to 85percent humidity in a sea climate. The intense ultraviolet radiation above theocean was also an issue. Stainless steel guide troughs protect all the cable-carriersystems from weather and the sun's rays. The cable carriers themselves are alsomade from a weather-resistant, corrosion-proof polymer material designed tohandle such conditions.

igus Malaysia Crane

igus Malaysia Crane

A look inside one of the crane's structure at the cable carrier and cables in action. Source: igus.


Thematerial used in these carriers is an igus proprietary polymer called igumid G,which is injection molded to create the cable carriers. Igus refers to itspolymers as triboplastics, because they are tribologically optimized materialcompounds (Note: Tribology is the branch of engineering that deals with theinteraction of surfaces in relative motion, their design and friction, and wearand lubrication). These triboplastic compounds are the basis of all igusproducts and systems.

In bulk-handlingapplications, cable drum and slip-ring corrosion is a common problem. Using motorizedcable drums for the cross travel would have required supplementary systemcomponents. The system would have therefore been more susceptible tomalfunction. For example, guiding the water hose would have required a seconddrum, as well as additional driving gear and controls, which could allpotentially malfunction. Similarly, if the trolley travel and cabin supply hadused a festoon system, a number of problems could have occurred due to thecorrosive climate and the long travel distance impacting the festooning andthereby jeopardizing operational safety.

Reduced Friction, Reduced Power Requirements
The igus solutionto supply the trolley is a cable-carrier systemthat does not require additional driving gears due to the use of igus' Rol-E-Chain, which isa roller chain system instead off a gliding chain typically used in suchapplications. The Rol-E-Chain's design reportedly decreases friction to a levelwhere travels of more than 2,600 feet are achievable at speeds up to 32.8 feetper second. The reduced friction means that the drive power required to movethe cable carrier is reduced by more than 25% compared to gliding chainsystems. These cablecarrier features, coupled with the fact that igus could provide the complete,fully harnessed system, was a major factor in Koch's and Siemens' decision towork with igus rather than source the different components needed from multiplesuppliers.

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