In launching its Model 3 harbour crane, Gottwald Port Technology GmbH has filled a gap in its current range of Generation 5 harbour cranes. First introduced in 2006, the Generation 5 cranes are gradually replacing their Generation 4 predecessors, outperforming them considerably in terms of lifting capacity, equipment level, versatility and degree of specialisation. The Model 3 machine is the entry-level model for the 100- tonne class, and is characterised by its compact, functional construction and high performance. In addition, Gottwald has come up with a number of innovations aimed at more efficient, competitive and environmentally compatible terminal and port operations.
The Model 3 harbour crane
The Gottwald Model 3 harbour crane features innovative drive technology and design, such as the three-phase-powered hoist and slewing gear units, and a broad range of optional features such as an energy-efficient hybrid drive, which will be discussed later in this article.
Moreover, the Model 3 machine has improved working speeds and a greater radius than its predecessor, the HMK 260 of Generation 4. The new model has a maximum radius of 46 metres (2 metres greater than that of the HMK 260), an installed maximum output of 895kW, and significantly increased working speeds, including hoisting speeds of up to 120m/min to improve productivity. Individually steered axles, tight turning circles and crab steering provide optimum manoeuvrability, while automation features for repetitive motions like propping the crane are also available.
Generation 5 harbour cranes offer maximum lifting capacities of 200 tonnes, working radii of up to 56 metres and are constructed using a modular design principle. The Model 3 machine has a maximum lifting capacity of 100 tonnes up to a radius of 20 metres, making it best suited to rapid container and general cargo handling alongside vessels up to standard class. For handling bulk materials, the Model 3 has a 34-tonne and 28-tonne motor grab curve with A7 and A8 classification respectively.
A range of optional features is also available. The optional load guidance system, for instance, assists the crane driver in achieving high handling rates, and includes linear load motion, load antisway, point-to-point handling and hoisting height limiting features.
As is usual with Gottwald harbour cranes, Model 3 is available as a rubber-tyred mobile harbour crane or rail-mounted portal harbour crane; as a barge-mounted floating crane, and as a pedestal-mounted stationary crane. Innovations in electrical drive technology
Like all Gottwald harbour cranes, Model 3 also uses electricity as its energy source – the most common, cost effective and environmentally friendly form of energy at ports and terminals. Model 3 cranes can be powered from an on-shore power supply; the use of on-board generators driven by combustion engines is then either bypassed or avoided completely. This boosts the high efficiency rating of electric drives, and maintenance costs for the inactive diesel generator unit are reduced or avoided. Exhaust emissions from the machines drop to zero and noise pollution is minimized. Hooking up to external power supplies also enables terminal operators to benefit from their own ‘green’ power sources.
In addition, when a mobile harbour crane is connected to the terminal electricity supply, it is possible to harness the energy from lowering and braking motions of the hoists and slewing gear units and return it to the harbour mains. The equipment needed to utilize external power supplies can be optionally fitted to all new Gottwald mobile harbour cranes.
Alternatively, the equipment can be retrofitted to older cranes by modifying the slip ring assembly and adding a cable reel, control box and – depending on the voltage available on-site (low or medium voltage) – the transformers required to step the external voltage supply down to the crane’s voltage. This option is of particular interest to customers based in regions where electricity costs are highly competitive, such as in Turkey, where around a third of the 50 Gottwald cranes installed use external power. Individual customers in Norway have reported cost savings of up to 50 percent, compared with running the crane via the diesel generator. Up to now, Gottwald has used DC drives for its hoists and slewing gear units in cranes of all sizes.
With the new Model 3, the electric drive concept has been expanded by employing threephase current technology for hoists and slewing gear units.
New hybrid drive – future-orientated andsustainable
If the local quay infrastructure does not allow the Model 3 crane to be connected to an external power supply, the optional hybrid drive is the key to improved efficiency; reductions in fuel consumption in a double-digit percentage range and lower exhaust gas emissions.
If the terminal does not provide direct access to low or medium voltage power, Gottwald mobile harbour cranes generate their own electricity via their on-board diesel generator, which has an installed power of up to 1,656 kW at a constant speed of 1,800 min-1 (at a frequency of 60 Hz). This electricity is made available to the crane’s power circuits at a voltage of up to 690 V. The generators have been designed to meet the requirements of EU Directive 2000/14/EC.
The hybrid drive itself consists of a combination of the on-board diesel-powered generator and electrostatic short-term energy storage – the energy recovered during the crane's lowering and braking actions is stored and then made available to the crane’s power system for the next work cycle.