Unloading containers on and off ships is big business. Crane manufacturers are always looking for new ways to move those boxes quicker and quicker. If a terminal can move 25 to 35 boxes an hour, an improvement of just one box per hour can mean that during the year it can take one extra ship, which is a significant revenue enhancement.
Finnish manufacturer KCI Konecranes came up with a relatively low cost enhancement last year, called the Boxhunter, which according to Mika Mahlberg, director of Konecranes VLC Container Cranes, offers productivity improvements in the region of 20%.
Konecranes studied all the cranes on the market and observed them in action. ‘We found that 50% of quayside crane time was spent on work cycle productive time,’ says Mahlberg – that is to say, moving containers at speed between ship and shore. ‘The other 50% of the time was spent on fine positioning, either positioning the spreader on the container, or putting boxes on boxes.’
To improve productivity, one option is to target the first 50% and specify higher speeds. But that creates other problems. Steel structures might need strengthening, or more power might be required. However you set about it, the cost goes up, Mahlberg says.
Instead Konecranes decided to target that second 50%, the slow bit where loads are carefully positioned. The solution is, conceptually, remarkably simple and one that Konecranes has used on its rubber tyred gantry cranes (RTGs) since it first brought its line out in 1995. Four auxiliary winches, one in each corner, act as a torque control system. Fitted with 16mm diameter rope, and set at an angle, the winches can sense the torque on the motor and so control the force on the rope.
The corner winches result in an active anti-sway system and a horizontal fine positioning system. This latter system allows the crane operator to move a container or spreader plus or minus 200mm sideways without moving the crane, Mahlberg explains, so for final positioning he does not have to move the trolley or the whole gantry.
Konecranes is currently building four of these Boxhunter cranes for Spanish customers, with two going to Terminal de Contenedores de Barcelona and two to Terminal de Contenedores de Algeciras. Each contract is worth about E11m and the first unit is being delivered in August. In addition, it is working on a E7m contract to modernise two cranes in San Juan, Puerto Rico, adding Boxhunter systems to Kocks cranes that have been working there for some years. Completion of this project is due next month.
A more complex solution to fine positioning of loads has been developed this year by Liebherr-Werk Nenzing, manufacturer of mobile harbour cranes. Called Cycoptronic, Liebherr describes the system as ‘the revolutionary cycle optimising electronic crane control system.’
With conventional control systems the crane driver must anticipate and counteract load sway by moving the boom tip. The longer the free suspended hoisting ropes are, the more difficult it is to control the load and the crane’s performance is heavily dependent on the skill of the crane driver.
The Cycoptronic system consists of sensors – described by Liebherr as ‘highly accurate, very robust and military approved’ – on the crane hook which send their output, via radio, to the crane’s Litronic control system. The dynamic behaviour of the crane’s structure has been measured in every position and with any load. This information is mapped into algorithms which have been programmed into the control system. The joystick position and the operator’s commands are also fed into the control system. With all this information, the crane automatically compensates for all rotational swing, transverse and longitudinal sway of the load by moving the boom tip.
The operator can select either conventional or Cycoptronic control, and if the load starts to sway under conventional control, the Cycoptronic option can be selected to steady the load ‘instantly’, according to Liebherr.
Liebherr claims that by automating one of the operator’s toughest challenges, crane performance is improved 10% even for the most skillful operators and as much as 80% for inexperienced operators.
Cycoptronic controls can be retrofitted to all Liebherr LHM 320 and LHM 400 models delivered in 1999 or later.
Instead of targeting the slow parts of the operation, another way to improve the efficiency of container cranes is to eliminate the unproductive actions. A spreader moving backwards and forwards between a ship and land is unloaded, and therefore unproductive, for half of the total distance that it travels. Among those seeking to eliminate what one might call ’empty hook syndrome’ is a Korean company called CreaTech.
CreaTech, established four years ago to develop port machinery, has patents for a horizontally circulating crane and a vertically circulating crane, called the Technotainer and the Swiftainer.
CreaTech’s concept is a high performance crane that has two hoisting trolleys and three circulating roller spreaders, which combine to move more than 70 boxes an hour, it is claimed.
The roller spreaders are separated from the headblock and circulate between the two hoisting trolleys. The boom of the crane has three tracks. One has the hoisting trollies, the middle one is for a returning empty spreader and the third one is for a spreader carrying a container.
With conventional cranes the spreader carries a box for half the time and is returning to its start point empty for the other half of the time. This way, there is always a container on the crane.
CreaTech claims that conventional ship-to-shore gantry cranes can be retrofitted with this technology by adding roller spreaders and three-track booms There have been double trolley cranes before, but according to CreaTech, this one is unusual in requiring only one operator. All movements are controlled by computers except for final positioning. When the spreader is lowered to about 5m off the ground, the operator takes control of the landside hoist for soft landing and locking. This soft landing operation is repeated by the operator for the seaside hoist.
CreaTech’s crane, as designed, has a capacity of between 51t and 61t and an outreach of 62m. It has a rail span of 30.5m and a backreach of 25m.
Evert Luttekes of the Delft University of Technology in the Netherlands has also addressed his thoughts to how container cranes can work to the full, all of the time. As container ships get bigger and bigger, he says, terminals have to invest in larger cranes, more terminal transport, larger stacks and improved hinterland connections to allow for the required high throughput. Berth performance must improve from the present 100 movements an hour to a level of 350 or 400 moves an hour.
Ultra large container ships demand a new concept for a reliable and efficient container crane with at least twice the present capacity, says Luttekes, because the conventional ship-to-shore crane is limited in capacity and speed of operation.
Luttekes’ concept is similar to that of CreaTech – turning the crane operation into more of a conveyor belt type of operation by using a circular system – but it achieves that goal in a different way. Containers are still lifted vertically by a semi static trolley over the ship and a second trolley above the quay, but containers are transported laterally between ship and quay by a circular system. This system makes use of carriers, running on rail tracks built into the crane on two levels. The capacity of this horizontal transport system will be sufficient to match the cycle times of the hoists, he explains.
The aim of the development of the crane is to boost crane capacity, but all functionality required in ship-to-shore handling has to be built in as well.
This ‘Carrier Crane’, as Luttekes calls his solution, is characterised by a quiet and controlled way of operation and a high level of automation. Luttekes claims that the expected operational performance will be about 65 to 70 moves an hour, which is sufficient for the required berth performance with five or six cranes on a ship.
The Carrier Crane was the subject of a paper at last month’s World Class Crane Management Seminar in Amsterdam. A more detailed explanation of the system will appear in a future issue.
A third approach to increasing productivity is to reduce downtime by taking advantage of maintenance best practice and crane monitoring technology. NorthPort and WestPort in Malaysia, for example, have both installed a new information management system called CODI (Container Operations Data Interchange). This system has been produced by E-Seaport.com, a Malaysian subsidiary of Argentinian crane manufacturer IMPSA. CODI is used to monitor the crane’s operational status and maintenance condition, complementing computerised terminal management systems and computerised maintenance management systems that may already be in place. Information gathered by CODI can be accessed anywhere, anytime over internet/intranet networks.
IMPSA says that more than 80 units of the CODI information management system, in various versions and configurations, have so far been installed in container ports worldwide, with 47 of them in Malaysia.
