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CARGO HANDLING
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Reeling under pressure in a weak market
meets the specification and has
reliable references, then it will be
considered (cf “Brand X or
equivalent”).
New container crane orders could
Cable manufacturers and cable management system
prises a rotating guide arm, Liebherr, for instance, tends to
fall somewhat this year, while the through which the cable passes, standardise on cable reels from
collapse of commodity prices will
suppliers are bracing themselves for what could be a
fitted to the cable basket mounted Stemmann-Technik, with which
dampen new investment in large
particularly difficult period in the marine and port
on the spreader that stows the ca- it has developed a good working
stockyard and quayside bulk han- ble around a core when being relationship over the years.
dling plant.
sector, despite ending last year with full order books
lifted.
That means that two of the This, ZPMC claims, maintains Typical
major markets open to the cable sufficient tension on the cable to A typical Stemmann installation
reeling and transmission indus- is based on standard technology mally exceeding 10 kW, and be- tainer cranes is to incorporate as prevent it being blown out of the using a 6.6kV supply would re-
tries have shrunk, while at the that is more than capable of han- coming lower as cable sizes reduce many in-house components and basket during lifting, while it also quire a 60mm diameter cable
same time competition, particu- dling the higher power require- in proportion to the high supply sub-systems as possible. This was collects the cable when the weighing around 6 kg/m. The reel
larly from Chinese suppliers, has ments of modern cranes. voltages being employed, sensitive not possible initially as the inter- spreader has been lowered and is outer diameter is dependent on
grown. control of this size of motor is not national market was reluctant to stationary over the container. travel distance and ground power
The frequency controlled, Common solution difficult, at least when compared accept some elements of Chinese ZPMC has also developed its supply connection.
torque-sensing direct drive system Power feed supply for mobile han- to the main hoist drives. technology, such as drive systems, own energy chain system that it The inner core diameter is
has taken much of the “guess- dling plant was considered a spe- AC frequency controlled ca- spreaders, cable reels etc, as the has now fitted on several ship-to- more crucial as, if it is too small,
work” and mechanical complica- cialised area due to the high power ble reel drives rely on easily modi- company has gained experience shore cranes, both for the domes- internal stresses will be generated
tion - such as electro-magnetic demands and travelling distances, fied software, which is relatively and a dominant position in the tic market, such as at Shanghai in the cable. To reduce this, a di-
slipping clutches, multi-stage albeit at relatively low speeds, cou- simple to replicate and thus the crane market, it has increasingly Waigaoqiao, and also outside ameter of some 2500mm is pre-
drives, two stage reeling/storage - pled with the restrictions on manufacturers’ individual me- been able to introduce its own China, with Long Beach operat- ferred, although this will depend
out of cable reel design. At the mounting space that require a chanical solutions to container components. ing this system. The ZPMC en- on the diameter of the cable,
same time, it has made this soft- monospiral reel mounted nor- crane cable feeds become, to a ergy chain is claimed to be capa- which in turn is a factor of the
ware-controlled technology avail- mally 10m above the ground. certain extent, less relevant. While Basket case ble of handling trolley speeds of transmission voltage.
able to a wider range of suppliers. These demands posed unique they are still listed in product port- It has, for instance, developed a up to 350 m/min and could pro- Thus, a 6.6kV cable may have
The other element of the problems, but torque control mo- folios, direct ac drive main feed spooling system for a spreader ca- vide a serious contender to sup- a diameter between 56 and 60mm,
power feed, the slip ring assembly tors can be individually tuned to reeling has now become standard. ble that can perform a similar pliers of similar E-chain systems while a 3.3kV cable will have a
to convert the rotating supply to meet these requirements, elimi- function to a spreader cable reel, when tendering to ZPMC. diameter of 60 to 65mm and
a static hard wired grid, has been nate elongation and compression In-house but without the necessity of a ro- weigh around 8 kg/m.
continually updated through the and extend cable life significantly. One of ZPMC’s central pillars to tary coupler or slip ring assembly. Flagship help One observation that may be
use of new materials. However, it With power ratings not nor- supplying relatively low price con- The cable winding system com- All the same, in one of ZPMC’s made from all of this is that it re-
flagship development projects, the quires an accurate set-up for guid-
fully automated and integrated ing the cable onto the reel.
yard handling system, the Chinese Liebherr also tends to use
group turned to Paul Vahle GmbH Stemmann’s festoon system, al-
- not for the power transmission, though it may instead source from
but for the data transfer system, Conductix-Wampfler. If the speci-
which is possibly a more crucial fication calls for the installation of
feature of this installation than the an energy chain, the company has
power supply. generally used Igus, although of
The system is based on Vahle’s course, all component suppliers
Slotted Microwave Guide (SMG) are subject to tender. Liebherr has,
that was originally developed for for example, fitted the Igus energy
high speed magnetic levitation chain system to cranes supplied to
trains - the first commercial ex- South Africa as well as the latest
ample is in operation in Shanghai crane supplied to Dublin Ferry
- but has also been shown to work Terminals.
on container crane trollies (eg in The successful operation of
Hong Kong). The system can this system prompted the opera-
transfer data at up to 10 Mb/sec tor to retrofit an existing
over six channels and, as it is con- Liebherr crane with a similar
tract-free, has a low maintenance system, to replace the conven-
requirement. tional festoon cable feed.
The system interfaces with the
most common bus systems, such Refining tradition
as (RS 232 C, RS 422/485, The development of energy
Ethernet, Allen-Bradley Data chains to provide a reliable high
Highway Plus, Allen-Bradley re- speed, high power transmission
mote I/O, GE Genius, etc) as well system has challenged the previ-
as special interfaces for video, au- ous dominance of traditional fes-
dio, control signal and emergency toon systems, causing suppliers to
shutdown transmission. further refine their products.
Its specification and cost are Conductix-Wampfler, for in-
well in advance of the require- stance, has developed a new con-
ments of individual container trol system logic for the motor-
crane demands, where fibre optic ised cable trolleys employed in its
or even copper connections high speed/longer travel festoon
through rotary couplings provide systems, in which the drive sys-
a sufficient level of data commu- tem is integrated to the master
nication. However, for a fully in- PLC of the container crane.
tegrated concept such as proposed The new motorised festoon
by ZPMC a more comprehensive control system is thus manufac-
and reliable system, such as the turer-independent and can be in-
SMG, is required. tegrated in all control systems that
Established contacts
are regularly available in the crane
market, where the selection of the
Many crane buyers are wary of frequency converter and other
naming a specific sub-supplier in control system components are
the overall tender as this does not becoming more important.
leave the crane builder any scope This system integration is also
to negotiate the supplier’s price, applicable to cable reel drives
and that would feed into the crane where it is possible to control the
price. As long as the equipment cable reel through the main PLC
Spreader cable basket spooling system from ZPMC...
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STEMMANN-TECHNIK GMBH
Fandstan Electric Group
www.stemmann.de
30 January 2009
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