Without the all-important nuts and bolts a RTG or RMG would not exist – it is that simple. Components manufacturers are secretly working behind the scenes to reduce costs in operations without affecting efficiency of the cranes. Here follows an update of recent developments in the component market from some of the leading companies in this field.
Brevetti Stendalto
One of the central issues that was always a problem in the past with container cranes was the installed cable chains that were required to perform flawlessly and continuously at fast speed over long travel distances and often in a critical working environment. The solution has been a technological challenge as it had to be combined with cost-effectiveness. As a result Brevetti Stendalto SpA from Italy recently launched their revolutionary SNS Technology – with the acronym standing for “Sliding Non Sliding” and reflects Brevetti’s classic sliding cable chain system with the benefits of wheels. The SNS Technology allows a cable chain to cover a travel distance of several hundred meters with basically no speed constraints. The technology has been tested on Brevetti’s heavy-duty masterpiece chain M80 with results the company describes as “so astonishingly positive” that the company is already working at extending its use to all sliding chain sizes, including the soon-to-be-marketed giant chain M100. One of the biggest advantages of the system is its cost. The system allows a 50% and above improvement on system performance and shows hardly any difference in price with current long-stroke technologies. The new cable chain system is simply based on Brevetti’s sliding skids and the use of wheels at specific locations of the guide channel. Wheels work where skids don’t, and vice versa.
Tratos
Another issue to be tackled was the twisting of the cables while in use. Twisting makes cable cores elongate unevenly which in turn leads to conductors on the outer layer of a strand face a greater risk of being broken. And a broken cable reeling at high speed is dangerous and can cause extensive and costly damage to equipment. Although various cable manufacturers have come up with a solution for the twisting of the cable the competition is fierce in this market sector. One company that has made strides is this area is Italian company Tratos who were awarded the largest order in the world for reeling cable for 38 ZPMC cranes for use at the latest Busan Port terminal in South Korea. Busan Port is the world’s fifth busiest container port and largest trans-shipment port in North East Asia. The port uses state-of-the-art facilities to enable it to handle more than 13 million TEU annually through active exchange with 500 ports in 100 countries, including the latest generation high speed container cranes, which often operate at speeds up to 300m/m. Earlier this year, the company completed the delivery of cranes’ cable lengths to Konecranes for use on 36 Automated Stacking Cranes (ASC) for their customer Abu Dhabi Ports Company (ADPC) for an automated container yard system in the United Arab Emirates’ Khalifa Port. The ASCs are being used with Tratosflex and Tratosgreen medium voltage rubber insulated and sheathed drum reeling cables. These cables are ideal for ASCs as they have been designed to combat the common problem of twisting that affects cables reeling at high speed. The cables will be used on one way reels with operation speeds of 200-300m/min and operate in temperatures ranging from -30°C to +80°C.
Powertec Generator System
Powertec Generator System Co Ltd from China has resolved the problem of shutting down eRGTs when they are switching from one stacking to another due to an interruption of power supply. According to the company the shutdown will cause the need to restart the paging system, electronic system, lighting and auxiliaries systems. The consequence of the power interruption not only affects the efficiency of the terminal operations it also affects safety due to the interruption of the paging system. In order to solve the problem Powertec has introduced their “Intelligent uninterrupted Power Transfer System” (IPTS) – a system that will prevent any power interruption while the eRTGC is moving from one stacking area to another. The IPTS involves the necessary modification of control and mechanical system preventing power interruption when the power is switching from generator-set to busbar electricity and vice-versa. According to Powertec this is the biggest benefit for eRTG stacking area movement. Not only does the system save 82% in idle time avoiding wear and tear on mechanical components due to system restart, it also shortens the restart of lighting on the eRTG from 20 minutes to zero. Yantian International Container Terminals (YICT) in Shenzhen is operating 200 RTGs and most of these have been modified as eRTGC. A year ago the terminal put the system on 10 of their eRTGs. Considering the high ROI of the system YICT has recently signed a new contract with Powertec for another batch of eRTGs.
Merford Cabins
According to cabin specialist, Merford from the Netherlands, RTG crane operators do have a specific field of vision in operations. The field of vision is completely different in comparison to operating an STS crane because the spreader is relatively closer to the cabin, thus the viewing angle is wider. Besides looking downwards between the operators’ legs a good view to the front and side is required. As a result the crane operator legs are often an obstruction. Looking around while driving the machine and looking sideways under beams while searching for trucks leads to difficult and uncomfortable postures. Movements sideways, in combination with the RTGs rubber tyres, create a swinging motion to the machine and cabin driver when starting and stopping the crane. Altogether it has a serious influence on human performance and well being. Depending on the height of the load (container), the viewing angle downwards is between 70 and 85 degrees. Based on personal preferences and feedback from the crane driver or based on the field of vision, the head inclination of the driver is realised by neck flexion, back inclination or a combination of both. In addition, the upper part of the body of the crane operator is “free in the air” and sideways movements also create a lateral load on the lower back. This aspect needs to be avoided in combination with a forward bended trunk. It is therefore recommended to make sure that the driver has an ergonomic seat that will give support in the above cases. Aware of the problems with clear vision for the operator Merford has teamed up with fellow Dutch company Orlaco, suppliers of heavy duty camera systems. The combination will see cameras installed on the cabin (or installed as separate system) to increase efficiency and safety. As an example for RTG cranes Merford provides images to the operator from behind a stack of containers to avoid dangerous situations in case “traffic” is present in that area. A camera system can be used to prevent a high stacked container being touched when moving backward preventing possible fall hazard to traffic under the crane. To support the operator with landing containers on a truck, lower positioned cameras can be a great help.