The strenuous, fast-paced operations of cranes at cargo-handling terminals around the world put immense pressure on cables that are reeling at increasingly incredible speeds. Fortunately, the manufacturers of the cable systems that help drive such frenetic operations are adept at delivering engineering excellence and intricate technological innovations. A paramount concern in this process is rigorous testing. “Life has always been hard for flexible cables installed on port equipment, especially cranes,” says Claudio Mauri, Sales and Marketing Director at Italian chains and cables supplier Brevetti Stendalto S.p.A. “They must prove reliable against the harshest working conditions: 24/7, non-stop heavy-duty operation, high speeds and acceleration, continuous mechanical stress and an aggressive environment to top it all off.” To ensure its products can satisfy such demands, the company makes full use of its testing facilities located at its headquarters in Monza, northern Italy. Among this testing equipment, Mauri details, is a “unique machine able to simulate a travel distance of up to 260 meters at any speed, ranging from 0.5 to 8 meters per second.” This is used to not only study new chain models, but also put cables through severe endurance tests.
“Cables from Europe’s most important manufacturers have spent some of their hardest lifetime in Monza. Not all of them survived,” claims Mauri. “It’s a due sacrifice to the benefit of port operators and crane manufacturers, who have reciprocated by increasing their trust in Brevetti Stendalto’s Total Chain solution.” German-based manufacturer of mobile energy supply and data transmission systems Conductix-Wampfler, part of the Delachaux Group, also emphasises its focus on research and development. Testing at its French Centre of Excellence enables the company to model, simulate and test prototypes to determine cables’ lifetimes under severe reeling applications. Its V-REX test facility in Weil am Rhein, Germany, provides the means to simulate a container crane system equipped with a monospiral, variable-frequency drive (VFD) reel, with maximum speeds of 300 meters per minute. The system can be electronically monitored and its results are analysed and put into the manufacturer’s optimisation processes for product development.
UK-headquartered global operator Tratos also notes the value of extensive research, both in the laboratory and simulated working conditions. This played a key role in the development of its Tratosflex-ESDB reeling cable, which was the subject of a massive order for the manufacturer last year.
The order to supply the Tratosflex-ESDB for 38 ZPMC automatic stacking cranes (ASCs) operating at the Port of Busan, South Korea, was described by Tratos as “the largest order in the world for reeling cable for high-speed cranes.” The manufacturer states that the Tratosflex-ESDB, which is used across many high-speed container cranes across the world, offers something different to other available reeling cables. It boasts that the cable is perfectly suited to the frenetic cargo handling at Busan – the fifth largest container port in the world and largest trans-shipment port in North East Asia – where it is required to reach speeds of up to 300 meters per minute.
Tratosflex-ESDB has been designed to combat the common problem of twisting in cables operating at high speeds, which can result in costly and dangerous equipment damage. The company’s engineers have modified the internal cable design, tightening the structure against the internal relative movement to accommodate high-speed applications. With a medium voltage rubber-insulated and sheathed drum reeling cable, Tratosflex-ESDB operates in temperatures from -20ºC to +60ºC. Conductix-Wampfler also notes the significance of overcoming the issue of twisting. It cites the importance of specially developed compounds to handle the strains of fast travel speeds, torsion stresses, abrasion and high tensile loads. For insulation, it mainly uses semi-conductive EPR (elastomere polypropylene) in the outer sheaths, mostly based on PCP (polychloroprene), or polyurethane for low voltage applications.
The company has developed intricate concepts to ensure twisting is no longer a frequent issue, especially in high voltage reeling cables. However, the manufacturer says the real challenge in contemporary operations is the burgeoning demand for composite cables that combine power, control and data transmission all in one cable – across all voltage ranges and applications in the ports industry. It states that fibre optics has a major role to play in this respect, through the elevated quality and quantity of data transfer. “We have only scratched at the full scope of opportunities with fibre optic technology in cables so far,” says the company’s Global Marketing Communications Manager, Michael Kusch. Optimising performance against the risks of high-speed operations was a major consideration for another notable Tratos order. This came earlier this year from Konecranes, for ASCs to be used in operations at Muelle Prat container terminal’s new 1,000-meter quay at the Port of Barcelona, Spain. Tratos is supplying 450 meters of medium voltage rubber-insulated and sheathed drum reeling cables for each of the 36 Konecrane ASCs. The Tratosflex cables, which the manufacturer states Konecranes now regularly specifies for its ASCs, are designed for high-speed reeling and utilise a unique internal design, with the stru
cture tightened against the internal relative movement. This, the manufacturer states, prevents the cable from twisting and leading to possible breakage. At Muelle Prat, operational speeds will be 270 meters per minute.
REVOLUTIONS PER MINUTE
Kabelschlepp recently launched a closed version of its new product family of cable and hose carriers, Tube TKA55, at the EMO Hannover trade fair in September. It describes the new plastic cable and hose carrier as being “perfectly leak-tight”, and as such particularly suited for use in dirty environments where chips and dust are created. It is also optimised for high operating speeds and rigid processes. Kabelschlepp calls the design “revolutionary” and describes the hose carrier as being particularly stylish, with minimum gap widths and a smooth side-belt contour. The company states that the very narrow gap width was achieved by a form-closed redesign of the covers. A further feature of the design is its integrated soundproofing. The chain is “very quiet” and, the manufacturer explains, offers optimised polygonal behaviour in the bend radius (BR), resulting in smooth running.
Kabelschlepp brags that, because of the new shape of the cable covers, the inside height can be fully stretched, even at BR. The manufacturer says that the covers can be loosened either inside or outside, facilitating the quick installation of cables and hoses, and making inspection work more efficient. Additionally, Kabelschlepp states, due to their stability, they provide perfect hold, even for hydraulic hoses. The design is intended to offer optimum durability; the interior of the chain is such that it can deal with extremely dynamic movements and forces, protecting coatings and insulation materials as well as internal components such as wires or strands in electric cables.
TKA55’s universal mounting brackets (UMBs) are designed to offer versatility, meaning it can be conveniently connected from the top, bottom and front. The inside covers are equipped with abrasion-resistant, robust skids in order to reduce wear and achieve the longest possible service life. Furthermore, the company details how the chain has been optimised in terms of weight, with reduced manufacturing times and use of materials combining to help lessen production-related CO2 emissions. Maintenance is also a large concern for global manufacturer igus, as evidenced by the PPDS Easy 2.0 condition monitoring system. igus is known for developing its Energy Chains as an alternative to festoon systems in supplying energy and data for trolleys on STS, RTG, RMG and bulk handling cranes.
With terminal operators wanting to minimise unexpected crane downtime as much as possible, the company has asserted the importance of constantly monitoring the condition of all critical components to make maintenance needs more predictable. The latest edition of PPDS, developed as part of its modular cable management system, was created to read the ‘push-pull forces’ of the moving system electronically, and shut it down safely if certain forces are encountered – for example a mechanical obstruction. If an error occurs, an alarm message is automatically generated. Stored data can also be retrieved and analysed retrospectively for up to three months. The data can track the chain’s operating condition and areas with abnormal variance, which can be caused by debris in the guiding trough, for example.The manufacturer states that its series of PPDS control systems have been successfully preventing downtime on STS, RMG, bulk handling and ship yard cranes, as well as other applications, for many years. Enhancements on this latest PPDS Easy 2.0 version include easier installation through the use of its plug-in connectors. The system features an integrated display and keypad to facilitate programming, while the new compact plastic housing is stable, corrosion-resistant and enclosed to IP 65 rating. Claudio Mauri states that Brevetti Stendalto has proven capable of fast and wide-ranging product enhancements in recent years, to keep pace with the demand for increasingly sophisticated solutions from port operators and crane manufacturers.
He details how the company’s Total Chain solution is delivered fitted with all its cables and wound up on drums for safe transportation and quick installation. The package is completed by a guide channel and various other accessories, along with on-site installation and commissioning services. Mauri adds that his company’s Total Chain solution can be found on thousands of RTG, RMG and STS cranes, as well as ASCs, around the world. Among Conductix-Wampfler’s other recent product developments is a specific multi-channel rotary joint for fibre-optics (TFO), with limited attenuation of less than 1.5 decibels, which is suitable for all types of cables and environment.
In 2010, it also launched a new level wind range for (un)loaders and stockyard equipments in bulk material handling. The company says that this features an innovative design for reducing weight and inertia, while increasing the mechanical resistance and heating dissipation compared to other traditional solutions. In addressing environmental concerns, Conductix-Wampfler patented a new magnetic coupler in 2006. Designed to deliver high efficiency and featuring the manufacturer’s VFD, this provides feedback to the network while unwinding. With pressure on both manufacturers and end-users to find alternatives to standard diesel power supply, reeling systems have emerged as a further solution, in addition to the conductor bar, for providing electric power to RTG cranes. The reeling syste
m is used to replace the main diesel motor, allowing up to 90% fuel savings, as well as increased efficiency and productivity. The firm adds that its dedicated range of gearboxes brings specific features for this application, such as vibration, speed, and lateral movement of the E-RTG.
KEEPING IT REEL
The innovations, intricate engineering, and strenuous testing that all go into developing cable solutions for powerful modern cranes are hugely impressive. The manufacturers in this market face incredible challenges to deal with the evolving strain caused by increasing cargo-handling speeds and volumes, but they seem more than up to the task.