Danish manufacturers Kroll Cranes A/S recently delivered two new portal mounted K-500L level luffing jib cranes to Syria.
Equipped with a tail radius of only 6m (20ft), the cranes can work closely together during ship unloading operations. With the radius at 25.9m (85ft), 20t (22USt) can be moved, while even at the maximum radius of 32m (105ft), 16t (18USt) can be lifted.
In contrast to most purpose-built harbour cranes, the Kroll cranes’ components were containerised, with crane component weights restricted to 15t (16.8USt) to make rigging easier.
Both characteristics are a familiar feature for construction cranes. Little wonder that Kroll Cranes intends to introduce a K-500L construction crane version with a 60m (197ft) boom as soon as an order will be placed for a 500m (1,640ft) luffing jib tower crane.
Some years ago, MAN Wolffkran GmbH successfully entered the high capacity luffing jib construction crane market by transferring a shipyard crane concept. The biggest European tower crane with luffing jib — the Wolff 60140B — found its roots in the B series of modular long reach slewing cranes delivered to ship yards in the Far East.
In contrast to the construction series version the wharf cranes were sitting on tubular towers and provide jib length of up to 100m (328ft) outreach. The well-known Wolff 320B construction crane can be traced back to the universal concept of the Wolff-Hydro introduced in 1985.
For the Lloyd Werft in Bremerhaven, which specialises in ship repair and conversion, MAN Wolffkran GmbH delivered two slightly modified Wolff 320BF tower cranes in 2001 and 2002. In contrast to the construction series model both fully frequency regulated driven cranes are equipped with a second hoisting winch serving a 5t (5.6USt) runner.
In fact, this winch located on the boom foot section is identical to the standard hoisting winch of the popular Wolff 180B luffing jib tower crane, demonstrating the modular design of the luffing dock cranes.
While one crane is towering on standard lattice tower sections, the higher one is fitted on a purpose built pipe column providing maximum rigidity. Instead of the standard tower crane cabin both cranes are rigged with a spacious, comfortable cabin and are travelling on purpose built portals alongside the dry dock.
Also the actual flagship of the Terex Comedil luffing jib tower crane line, the CTL 630-24, found a ready market in the construction industry as well as in the shipbuilding industry. In 2002 the Grand Bahama Shipyard opened one of the largest floating docks in the world with a lifting capacity of 82,500t (92,400USt), served by two specially designed travelling gantry mounted CTL 630-24 level luffing jib cranes supplied by MPS Comedil.
The tower cranes with 50m (164ft) boom and movable ballast offer a maximum lifting capacity of 24t (27USt), rigged on only a 5.47m (18ft) narrow purpose built portal.
If requested, the CTL 630-24 can be equipped with a secondary 8t (9USt) hoisting winch, located under the jib foot section. Besides tower crane uppers of the HC-L, EC-H series, construction cranes mounted on portals across the wide range of the Liebherr crane range also provide uncommon crane component combinations.
A number of maritime crane uppers manufactured by the Liebherr–Werk Nenezingen GmbH are delivered to Far East ports and shipyards. As original multi purpose deck cranes, crane uppers of the CBW and GBG line provide system integrated design features for the harsh waterfront application. Combined with a purpose built travelling gantry and a tubular mast supporting the slewing ring, these units are versatile dock cranes.
Potain show off a broad experience in modified tower cranes for special application duties at storage yards and in the shipbuilding industry. Upper capacity models of the MDTN range with the characteristic topless design features are attracting growing interest.
The latest version is the MDTN 462 ordered by the Alstom marine-Chantiers de l’Atlantique company. Thanks to the topless jib design, the tower crane can work under a 61.5m (202ft) high goliath crane, providing a maximum under hook height of 47.6m (156ft). At the 50m (164ft) jib end the maximum capacity of 8.7t (9.7USt) can be extended as an option to 10t (11.2USt). The maximum load of 20t (22USt) can be handled at a 24.7m (81ft) radius.
Fitted with a tubular mast for unlimited life span the crane is rigged on a travelling portal with different leg heights to cope with the 550m (1,804ft) long track already installed at the shipyard.
A permanent elevator for 300kg or three people installed inside the mast enables easy access to the Potain “vision” comfort cabin fitted with air-conditioning and toilet.
The 150 LCC hoisting mechanism provides continuous-current technology with variable frequency trolley and slewing functions.
The universal concept of the original Link Belt “Tower Gantry” (TG) crane range makes this powerful diesel hydraulic cranes suitable for heavy construction work as well as shipyard application.
While Cornell & Company Inc, for example, delivered two TG-2300 on customer built portals for general cargo handling at the Gateway Terminal in New Haven, Connecticut, Jake’s Crane engineering division installed a redesigned TG 1900 crane on an in-house built portal for South-West Marine Inc.
In many cases original construction cranes find a second life as wharf cranes. For example, Favelle Favco Cranes supplied a refurbished Favco STD 350 model with 30m (98ft) boom fixed to a pontoon.
This unique “floating tower crane” is working in Singapore serving tugboats and small ocean liners. In single line fall operation mode 7t (8USt) can be lifted. In double fall condition the diesel hydraulic powered crane is rated for 10t (11USt).
An economical way of portal design is found in a second example by using spare tower sections for most of the portal structure. The travel base has steering capacities to negotiate curves on the wharf parameter. Delivered to an Australian wharf for servicing and maintenance work as well as general cargo lifting work like containers, the engaged series crane M300D is rigged with 36.6m (120ft) boom. At 10m (33ft) minimum radius, 32t (36USt) can be handled. The maximum capacity at a 37m (121ft) radius is 8t (9USt).
In Europe, older bottom slewing luffing tower cranes are intensively used as outfitting cranes on larger wharfs and high capacity cranes on small river shipyards. Besides Liebherr A-crane models Peiner T and TN dominate the scene. In most cases the luffing jib provides sufficient height reaching through high ship structures during fitting out duties.
Hence the towers of the crane are limited to the base sections. Apart from widespread portal applications as undercarriages in Bremerhaven, a unique fixed foundation for a Peiner TN85 is used. The bogies of the standard undercarriage are removed.
Thereafter the cross-shaped 5 x 6.3m (16 x 21ft) undercarriage was mounted on a purpose built steel grid resting on a central column. In some cases the shipyard itself redesigned the original standard tower crane. At the shipyard “Duijvendijk” in Krimpen a/d Iissel, in the Netherlands, an upgraded Richier GT1427 SP11 is operated. Instead of the standard 40m (131ft) saddle jib, a 50m (164ft) jib is rigged by adding a separate second pendant line, enlarged tower head and adding low profile jib sections to the jib and counter jib foot section. While the maximum capacity is restricted to 40t (45USt), 5t (6USt) can still be lifted at a 50m (164ft) radius. The crane is rail mounted on a 6 x 6m (17 x 17ft) portal shaped undercarriage.
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Tower cranes – a helping hand for shipyards
Shipbuilders in Europe and the Far East have been quick to exploit the advantages of the tower cranes. Unlike most shipyard cranes, tower cranes are series manufactured, which provides immediate cost benefits as well as ensuring the supply of spare parts and short delivery time. By using second hand construction cranes or rental options of the whole crane or crane parts initial investment can be kept under a tight lid.
Although very heavy lifts must be left to the big traditional purpose built shipyard cranes, new large series tower cranes are gaining market share as specialised versions in the plus 1,000mt class. With an installed tower crane super lift capacity on a wharf, like that provided by goliath cranes, it is free to do the job it is built for. Meanwhile, the speed and flexibility of the tower crane increases the productivity of the workforce.
For smaller outfitting wharfs or river wharfs the tower crane will be the most economic main workhorse. Main restrictions of the tower crane application are found in the required design norms for long lasting heavy-duty work.
Economically, most construction cranes are designed following the lowest international standard, group one or group two.
For continuous around the clock work the strict standard H1/B3-DIN15018 or A3 is desired leading in many cases to load chart reductions of a standard tower crane working on shipyards. Furthermore, harsh environmental conditions lead to special adaptations of the crane like enclosed machinery rooms, adding to the costs of tailor made modular cranes.
Generally, slewing cranes integrating a high amount of standard tower crane elements can’t provide the advantage of uncluttered outside surfaces and minimum areas requiring maintenance of the paintwork realised by purpose built shipyard cranes where tubular and box-section construction is dominating.
While the standard tower crane will be the most economic lifting tool for light and medium loads to be handled for the construction and outfitting of small to medium ships, a higher degree of specialisation is recommended for larger cranes. Modern tower crane designs provide proven crane modules, which can be combined with non-serial designs to a versatile individual unit.
