5 Key Applications of Reeling Cable in Port Cranes, Spreaders, and Material Handling
In today’s highly competitive container terminal, the ship-to-shore cranes, yard cranes, and material handling equipment run almost around the clock, serving the global supply chain network. Hidden inside these colossal structures lies an important yet underrated part, which is the reeling cable.
In terms of port handling, the performance of the reeling cable affects the availability of ship-to-shore (STS) cranes, spreaders, and yard equipment. This paper discusses five vital applications of reeling cables in ports and explains how to choose the appropriate type to avoid downtime in the port facility.
1. Reeling Cable Application in Ship-to-Shore (STS) Cranes
Ship-to-Shore (STS) cranes are the largest structures in a container terminal, responsible for loading and unloading vessels. The cranes traverse the quay by means of a rail mounted to the side of the quay. In the course of movement, there is a need for a reliable power supply capable of spanning several hundred meters.
The reeling cable technology is employed within a large, motor-driven cable reel system for STS cranes. As the crane runs parallel to the quay, the cable reel is automatically controlled in coordination with the main drive to ensure proper handling of the long cable runs and voltages, usually between 6.6 kV and 20 kV.
Technical Advantages and Performance
High-speed cable winding of more than 120m/min is achieved using reeling cables in STS systems without any losses or breakdowns. Modern STS systems favor reeling cables because they provide a clean, managed solution compared to traditional festoon systems, which can be susceptible to wind interference and mechanical wear over long distances.
Practical Considerations
Cables used in the STS system need to be equipped with outstanding characteristics of resistance against torsion. When loading a rope on the drum under pressure, a twisting force (torsion) can arise if its inner parts are out of balance. Moreover, the sheathing needs to be durable to salt spray, ozone, and UV resistance because the quay is very corrosive. To provide additional structural stability, engineers typically opt for the cable with a special anti-torsion sheath, which is either made from polyester or aramid yarn and located between inner and outer layers of sheathing.
2. Reeling Cable Application in Rubber-Tired Gantry (RTG) Cranes
As the main machines used at terminals, rubber-tyred gantry cranes are used for stacking/retrieving containers. Historically, rubber-tired gantry (RTG) cranes have been equipped with diesel engines generating electric power. Nevertheless, today the transition is quickly taking place towards "E-RTG" cranes.
The conversion to E-RTG relies heavily on reeling cable systems. The cable reel is mounted on the RTG structure, connecting to a ground-level power point. As the RTG moves between container blocks, the cable is automatically managed by the reel.
Operational Benefits
Transitioning to reeling cable systems in RTGs significantly improves energy efficiency. Data from electrified ports indicates that E-RTGs can reduce energy costs by up to 60-80% compared to diesel-powered units. Furthermore, because electric motors require less maintenance than internal combustion engines, overall crane uptime is increased.
Technical Specs for RTG Reeling
RTG applications typically involve low- to medium-voltage (400V to 1kV). The primary challenge here is the frequency of "starts and stops" and the potential for lateral movement as the RTG steers between stacks. Therefore, flexibility and high tensile strength are non-negotiable. Cables with a polyurethane (PUR) or specialized rubber jacket are preferred for their high abrasion resistance, as the cable may occasionally come into contact with the ground or guide channels.
3. Reeling Cable Application in Rail-Mounted Gantry (RMG) and Automated Cranes
RMG cranes and automated stacking cranes (ASCs) are essential in transitioning into completely automated ports. While RTGs move using rubber tires, RMG cranes use rails, making it possible for them to achieve high speed and accuracy.
In such machines, the reeling cable serves as the main medium for transmitting information and power. Given that most of these machines are usually automatic, the reeling cable needs to not only transmit electrical energy but also provide communication between the crane’s PLC and the terminal operating system (TOS).
High-Speed Performance
Automated cranes move at high velocities, sometimes reaching 300 meters per minute. The reeling cable must be able to withstand the rapid acceleration and deceleration forces without stretching. To achieve this, high-end reeling cables incorporate a central strength member made of aramid fiber (Kevlar) or specialized vulcanized textile elements to absorb the pulling force.
Integrated Fiber Optics
A critical practical point for RMG applications is the use of "hybrid" reeling cables. These cables contain traditional copper conductors for power, along with integrated fiber optic (FO) cores. Fiber optics allows for high-bandwidth data transmission, enabling remote monitoring via high-definition cameras and low-latency control signals, which are essential for safety in automated zones.
4. Spreader Reeling Cable Application in Vertical Lifting in Container Handling
The spreader is the device that physically latches onto a container. It is suspended from the crane’s trolley and moves vertically to pick or place containers. To power the twist-locks, sensors, and flippers on the spreader, a dedicated reeling cable (often called a spreader cable or basket cable) is required.
While the gantry travel cables move horizontally, spreader cables move vertically at high frequencies. They are often wound on a reel located on the trolley or allowed to gather in a "gravity basket."
Enduring Mechanical Stress
The spreader cables in a port environment are subjected to the most difficult mechanical stresses. The cables are subjected to vertical pull, fast winding, and high vibration. In case the spreader cable breaks down, the whole crane becomes ineffective since it becomes impossible to secure the hold on the containers.
Material Selection: PUR vs. Rubber
In vertical lifting, light but durable cables are required. PUR jacketed cables are highly recommended for spreader cables due to their increased resistance to tearing and oil. PUR cables are also denser than rubber, hence the smaller bend radius. Spreaders also need short-lay cables where the wires inside the cables are more tightly twisted.
5. Reeling Cable in Other Material Handling Equipment
Beyond the primary cranes, reeling cables are utilized in various other port and industrial material-handling equipment. This includes Mobile Harbor Cranes (MHCs), bulk ship loaders/unloaders, and heavy-duty conveyor systems.
Mobile harbor cranes often use reeling cables when they are plugged into the quay’s power grid to save on diesel fuel during long loading cycles. Similarly, bulk handling equipment that travels along the length of a jetty requires reeling systems to manage the power supply as the loader moves to different hatches of a ship.
Versatility and Efficiency
The employment of these reeling cables in such activities diminishes the potential dangers connected with hand cabling, including stumbling, harm to the cables through the operation of machinery at the construction site; and wrong terminating practices. Reeling cables provide a self-sufficient system of power administration, guaranteeing effective material movement and enabling non-conventional equipment to run as reliably as the primary quay crane.
Practical Maintenance Tips
- Visual Examination: Routinely examine the exterior of the cable jacket for evidence of "bird-caging" (where the conductors bunch up and push through the jacket) or "corkscrewing," which indicates improper tension or torsion.
- Alignment: The cable should be aligned precisely with the cable guide or trench; otherwise, it will wear out rapidly owing to its constant friction against the drum's flanges.
- Tension Check-Up: Torsional force readings on the electrically driven drum must be regularly verified to prevent unnecessary stretching or slackness of the cable.
- Hygiene Practices: Maintain a clean drum and guide rollers. Sand and salt accumulation serve as an abrasive agent that gradually erodes the cable jacket.
Conclusion
Reeling cables are the vital links that enable the continuous movement and automation of modern port equipment. By understanding the specific requirements of each application—whether it is horizontal travel on the quay or vertical lifting with a spreader—terminal operators can select the right cable specifications to maximize equipment lifespan.
If you are currently sourcing reeling cables for a port project or looking to upgrade your RTG fleet to electric power, we offer high-performance reeling cablesolutions.Contact us todayfor a technical consultation, or visit our product pages to view our full range of industrial cables.
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about HEBEI- HUATONG
Founded in 1993, Hebei-Huatong is a global cable manufacturing enterprise with production facilities located in Tangshan (Hebei Province, China), Busan (South Korea), Panama, Kazakhstan, Tanzania, Cameroon, and Angola. Its core product portfolio includes submersible pump cables for oil extraction, flexible moving cables for harbor cranes, cUL/CSA listed cables for AI PDU and marine shipboard cables. The company provides robust support for the continuous, safe, and efficient operation of industrial sectors worldwide, including offshore and onshore oil & gas exploration, and material handling via port cranes.
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